Subject: Aggregate with identical learned route
From: "Tsillas, Jim" <[email-masked]>
To: "[email-masked]'" <[email-masked]>
Date: Fri, 31 Aug 2001 08:58:34 -0400

What is the common practice among vendors for this
case: an aggregate is confirgured to distribute both
the aggregate prefix and all the longer prefixes. The
peer receives a route which exactly matches the
aggregate prefix.

Since this prefix is not more specific it shouldn't
participate in the aggregate and should be propagated
normally. 

Now if the peer learns a prefix which does participate,
should (a) the peer not propagate the aggregate prefix
(since it is already being propagated through the learned
route) or (b) propagate the aggregate and not use the
learned prefix (until the aggregate is not active).

I'm tending towards (a) because (b) would incur loss of
routing information.

Thanks in advance for you help.

-Jim.

Date: Fri, 31 Aug 2001 00:07:59 +0400
From: Alex Zinin <[email-masked]>
Reply-To: Alex Zinin <[email-masked]>
Organization: Nexsi Systems
To: Jeffrey Haas <[email-masked]>
Cc: [email-masked]
Subject: Re: re-posting a message
Sender: [email-masked]

Jeffrey,

>> > I also thought we wanted 2385 to go away.
>> 
>> I guess I missed this discussion, can you send me the pointers
>> privately?

> This is mostly verbal from various people.
> TCP MD5 is a hack, although a well supported one on various vendors' routers.
> IP-Sec seems to be what the same crowd has suggested.

Understood.
I think it makes sense to mention 2385 for informational
purposes, since those who implement BGP will need to
seriously consider supporting it given the current
deployment environment.

Alex.

Date: Thu, 30 Aug 2001 12:54:19 -0400
From: Jeffrey Haas <[email-masked]>
To: [email-masked]
Subject: Re: re-posting a message
Sender: [email-masked]

On Thu, Aug 30, 2001 at 02:07:54AM +0400, Alex Zinin wrote:
> > I also thought we wanted 2385 to go away.
> 
> I guess I missed this discussion, can you send me the pointers
> privately?

This is mostly verbal from various people.
TCP MD5 is a hack, although a well supported one on various vendors' routers.
IP-Sec seems to be what the same crowd has suggested.

> Alex.

-- 
Jeff Haas 
NextHop Technologies

Date: Thu, 30 Aug 2001 02:07:54 +0400
From: Alex Zinin <[email-masked]>
Reply-To: Alex Zinin <[email-masked]>
Organization: Nexsi Systems
To: Jeffrey Haas <[email-masked]>
Cc: Eric Gray <[email-masked]>, [email-masked]
Subject: Re: re-posting a message
Sender: [email-masked]

Jeffrey,

> On Thu, Aug 23, 2001 at 01:45:26PM -0400, Eric Gray wrote:
>>     I believe that the reference to RFC 2385 is with respect to text
>> about an "authentication scheme used by the transport protocol",
>> rather than "BGP's own authentication mechanisms."

> Sorry, I was responding to the underlined section, thus:

It's my fault, underlined a wrong line. Eric is right I meant the
transport-specific schemes.

>> > >    acknowledgment, and sequencing.  Any authentication scheme used by
>> > >    the transport protocol may be used in addition to BGP's own
>> > >    authentication mechanisms.  The error notification mechanism used in
>> > > // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> > > // Reference to RFC2385 here?

> So, something along the lines of:

> Any authentication scheme used by the transport protocol, such as
> RFC 2385 or IP-Sec, may be used in addition to BGP's own authentication
> mechanisms.

Yes, but ref'ed with [?], of course.

> I would be hesitant to actually specify any of these mechanisms. 
> I believe it implies the blessing of the protocol.

Not more than any other reference in a document.

> I also thought we wanted 2385 to go away.

I guess I missed this discussion, can you send me the pointers
privately?

Thanks,

Alex.

Date: Thu, 30 Aug 2001 01:56:41 +0400
From: Alex Zinin <[email-masked]>
Reply-To: Alex Zinin <[email-masked]>
Organization: Nexsi Systems
To: Eric Gray <[email-masked]>
Cc: [email-masked], Yakov Rekhter <[email-masked]>
Subject: Re: re-posting a message
Sender: [email-masked]

Eric,

 Thanks for the comments and sorry for the delay.
 See below, pls.

-- 
Alex Zinin

Friday, August 17, 2001, 6:29:36 PM, Eric Gray wrote:

> Alex,

>     Doing a little re-posting (or is it riposting), myself.
> Apparently my prior post bounced.  See comments in-line below...

>>    conforming to the "hop-by-hop" routing paradigm.  Since the current
>>    Internet uses only the "hop-by-hop" routing paradigm and since BGP
>>    can support any policy that conforms to that paradigm, BGP is highly
>>    applicable as an inter-AS routing protocol for the current Internet.
>>
>> // The last sentence is not entirely correct anymore (i.e., MPLS TE is
>> // there) I think it can be changed to say hop-by-hope inter-AS routing.

> Freudian?  Okay as "... hop-by-hop inter-AS ..." - otherwise, it is routing
> by leap of faith...

Ha-ha :)) I guess it is Freudian indeed.
Agreed on "hop-by-hop".

>> Expiration Date October 2000                                    [Page 3]
>>
>> RFC DRAFT                                                     April 2000
>>
>>    planned to explore various aspects of BGP application.  Please send
>>    comments to the BGP mailing list ([email-masked]).
>> //                                  ^^^^^^^^^^^^^^->"[email-masked]"?

> Likewise guaranteed to be obsolete eventually - possibly better to omit?

May be the text should refer to the WG homepage, something like:
"...to the BGP mailing list (please refer to the IDR working group
homepage at http://www.ietf.org/html.charters/idr-charter.html)"

>>    NEXT_HOP address.  This is known as a "third party" NEXT_HOP
>>    attribute. A BGP speaker can advertise any adjacent router in the
>>    NEXT_HOP attribute provided that the IP address of this router was
>>    learned from an external peer and the external peer to which the
>>    route is being advertised shares a common subnet with the NEXT_HOP
>>    address. This is a second form of "third party" NEXT_HOP attribute.
>>
>> /* Reword the above as follows:
>>
>>    The NEXT_HOP path attribute defines the IP address of the border
>>    router that should be used as the next hop to the destinations listed
>>    in the UPDATE message. The NEXT_HOP attribute is calculated as follows.
>>
>>      1) When sending a message to an internal peer, the BGP speaker
>>         should not modify the NEXT_HOP attribute, unless it has been
>>         explicitly configured to announce its own IP address as the
>>         NEXT_HOP.

> This is more than a rewording - this text does not appear to be either
> explicit or implicit in the text being re-worded (which seems to talk
> about advertisements to _external_ peers only).  Not that it is wrong,
> as far as I can tell, but it is added text rather than reworded text.

The first part of it is below, as you mention yourself. The second
part (after ", unless") is new and reflects common practice.

>>
>>
>>      2) When sending a message to an external peer X:
>>
>>         o If the route being announced was learned from an internal
>>           peer or is locally originated, the BGP speaker can use for
>>           the NEXT_HOP attribute an inerface address of the internal

> ... interface address ...

Agreed.

>>
>>           peer router through which the announced network is reachable
>>           for the speaker, provided that peer X shares a common subnet
>>           with this address. This is known as a "third party" NEXT_HOP
>>           attribute.

> Might be better to say "This is a form of 'third party' NEXT_HOP attribute."

Agreed.

>>
>>
>>         o If the route being announced was learned from an external
>>           peer, the speaker can use in the NEXT_HOP attribute an
>>           IP address of any adjacent router (known from the received
>>           NEXT_HOP attribute) that the speaker itself uses for local
>>           route calculation, provided that peer X shares a common
>>           subnet with this address. This is a second form of "third
>>           party" NEXT_HOP attribute.
>>
>>         o If the external peer to which the route is being advertised
>>           shares a common subnet with one of the announcing router's
>>           own interfaces, the router may use the IP address associated
>>           with such an interface in the NEXT_HOP attribute. This is known
>>           as a "first party" NEXT_HOP attribute.
>>
>>         o By default (if none of the above conditions apply), the BGP
>>           speaker should use in the NEXT_HOP attribute the IP address
>>           that is used to establish the BGP session.
>>
>> */
>>
>>    Normally the NEXT_HOP attribute is chosen such that the shortest
>>    available path will be taken.  A BGP speaker must be able to support
>>    disabling advertisement of third party NEXT_HOP attributes to handle
>>    imperfectly bridged media.
>>
>>    A BGP speaker must never advertise an address of a peer to that peer
>>    as a NEXT_HOP, for a route that the speaker is originating.  A BGP
>>    speaker must never install a route with itself as the next hop.
>>
>>    When a BGP speaker advertises the route to an internal peer, the
>>    advertising speaker should not modify the NEXT_HOP attribute
>>    associated with the route.
>>
>> // This part is covered above, so should be removed.

> I believe you refer to the text I pointed out as being added, correct?
> In that case, 'this part' should refer only to the paragraph immediately
> above - is that right?

Right.

>> 5.1.4   MULTI_EXIT_DISC
>>
>>    The MULTI_EXIT_DISC attribute may be used on external (inter-AS)
>>    links to discriminate among multiple exit or entry points to the same
>>    neighboring AS.  The value of the MULTI_EXIT_DISC attribute is a four
>>    octet unsigned number which is called a metric.  All other factors
>>    being equal, the exit or entry point with lower metric should be
>> //                  ^^^^^^^^^^^^^ this should be just entry point

> I don't understand this one.  I would have thought 'just exit' would make
> more sense, if you were going to get rid of one or the other.  Also, if
> you get rid of one here, why would you leave it at the beginning of the
> paragraph?

The deal is that MED reflects the IGP distance inside the remote AS,
not the local one. Hence, we're not really selecting an exit from
the local AS when we look at the MED value, but the entry point
to the neighboring AS. One could argue though, that an entry point
to one AS is an exit point from another..., besides, the name
of the attribute has "_EXIT_" in it :)

>>    preferred.  If received over external links, the MULTI_EXIT_DISC
>>    attribute MAY be propagated over internal links to other BGP speakers
>>    within the same AS.  The MULTI_EXIT_DISC attribute received from a
>>    neighboring AS MUST NOT be propagated to other neighboring ASs.
>>
>>    A BGP speaker MUST IMPLEMENT a mechanism based on local configuration
>>    which allows the MULTI_EXIT_DISC attribute to be removed from a
>>    route.  This MAY be done either prior to or after determining the
>>    degree of preference of the route and performing route selection
>>
>> // I believe the above should say only "prior". Otherwise, we can
>> // have inconsistent decisions in the same AS.

> I think this is satisfied if the 'mechanism based on local configuration'
> establishes a consistent decision point within an AS.

My understanding of the phrase "mechanism based on local
configuration" is that it is a piece of code running within a box
that allows MED to be removed. So, it's just a means of doing
things, but, by itself, it cannot guarantee consistency within
an AS. If one box is [not] using an attribute in its path selection
algo, other boxes in the AS should do the same.

>>          In response to the ConnectRetry timer expired event, the local
>>          system restarts the ConnectRetry timer, initiates a transport
>>          connection to other BGP peer, continues to listen for a
>> //                     ^^^^^->"the" ?

other =>> the

>>
>>
>> ...
>>
>>          In response to the ConnectRetry timer expired event, the local
>>          system restarts the ConnectRetry timer, initiates a transport
>>          connection to other BGP peer, continues to listen for a
>> //                     ^^^^^->"the"?

other =>> the

It's minor, but I guess either "the" or "the other" sounds better,
as we're talking about a specific neighbor on the other side of
a specific connection.
I'll trust native English speakers, though :)

>> ...
>>
>>          If there are no errors in the OPEN message, BGP sends a
>>          KEEPALIVE message and sets a KeepAlive timer.  The Hold Timer,
>>          which was originally set to a large value (see above), is
>>          replaced with the negotiated Hold Time value (see section 4.2).
>>          If the negotiated Hold Time value is zero, then the Hold Time
>>          timer and KeepAlive timers are not started.  If the value of
>>          the Autonomous System field is the same as the local Autonomous
>>          System number, then the connection is an "internal" connection;
>>          otherwise, it is "external".  (This will effect UPDATE
>> //                                                ^^^^^^->"affect"?

> Valid either way, though 'effect' is closer because it more directly
> relates to cause.

> (See meaning 1 @ http://www.dictionary.com/cgi-bin/dict.pl?term=affect
> and meaning 2 @ http://www.dictionary.com/cgi-bin/dict.pl?term=effect

My point is that the text should read as whether a connection is internal
or external will _affect_ processing of UPDATEs, not _effect_ (i.e.,
produce) UPDATE message processing.

>>
>> ...
>>
>>       - In order to achieve successful distributed operation, only
>>       routes with a likelihood of stability can be chosen.  Thus, an AS
>>       must avoid using unstable routes, and it must not make rapid
>>       spontaneous changes to its choice of route.  Quantifying the terms
>>       "unstable" and "rapid" in the previous sentence will require
>>       experience, but the principle is clear.
>>
>> // Care must be taken to ensure that BGP speakers in the same AS do
>> // not make inconsistent decisions.

> Is this an editorial comment, or are you proposing to add this text?

It is a proposed phrase.

Alex.

From: Katia Linker <[email-masked]>
To: "[email-masked]'" <[email-masked]>
Subject: UPDATE msg error subcodes
Date: Tue, 28 Aug 2001 15:20:12 +0200
Sender: [email-masked]

Hi !
When the UPDATE msg error subcode
OPTIONAL ATTRIBUTE ERROR is used ?
  Thanks in advance
   Katya

content-class: urn:content-classes:message
Subject: AS-path aggregation  and confederations
Date: Mon, 27 Aug 2001 09:16:28 +0300
From: "Tomer Kol" <[email-masked]>
To: <[email-masked]>
Sender: [email-masked]

Hi,
I have a question related to BGP4 as-path aggregation within
confederation.

In the following 1 2 denotes an AS-sequence, {1 2} an AS-set,
(1 2) a confed sequence and [1 2] a confed set.

Consider the following setting, wherein ASxxx denotes a router inside AS
xxx,
and all 65xxx ASs are confederation peers inside confederation AS 1.

    AS65020	\	/AS65001  \	
		 AS65004	     -	  <---- AS-PATH   2 3 {10  11}
AS20	_______/	\AS65005  /	

Route 5.3.2.0/23 whose as-path contains a sequence segment 2 3, and
a set segment {10,11} enters AS 1 via AS65001, and route 5.3.128.0/17
with 
a similar as-path enters it via AS65005.
Now assume that these routes reach AS65004 and are aggregated (with
the as-set option) to 5.3.0.0/16 by a router in the 65004 AS.

As far as I understand it, the resulting aggregate route should have 
( i) an as-path of  (65004)[65001 65005] 2 3 {10 11}    when sent to
AS65020
(ii) an as-path of   1 2 3 {10 11}                      when sent to
AS20 

When placing a leading vendor's router as the AS65020 router, it dropped
the
BGP session upon receiving an update with an AS-path of the former type,
i.e., with an as-path attribute of (65004)[65001 65005] 2 3 {10 11}.
The notification error code was 3 (update message error) with a sub-code
11
(Malformed AS-path).

AS-path (i) seems perfectly legal according to RFC 3065, and, using
ethereal,
the update messages sent seems to be correct.

To check what that leading vendor's router would have done, I've placed
it as 
AS65004, and got:
( i)  advertised to AS65020      (65004) {2 3 10 11}
(ii)  advertised to AS20         1 {2 3 10 11}

Which also comply with the RFC, but loose a lot of information.

Am I missing something?

           Tomer

Date: Sun, 26 Aug 2001 21:49:14 +0000
From: Andrew Lange <[email-masked]>
To: Katia Linker <[email-masked]>
Cc: "[email-masked]'" <[email-masked]>
Subject: Re: UPDATE msg error handling
Sender: [email-masked]

Hello,

The malformed AS_PATH error subcode is used to indicate a syntactic error
in the AS_PATH attribute.

The format of the AS_PATH attribute is:

 b) AS_PATH (Type Code 2):

            AS_PATH is a well-known mandatory attribute that is composed
            of a sequence of AS path segments. Each AS path segment is
            represented by a triple <path segment type, path segment
            length, path segment value>.

Rekhter & Li                                                   [Page 14]
RFC 1771                         BGP-4                        March 1995

            The path segment type is a 1-octet long field with the
            following values defined:

                  Value      Segment Type

                  1         AS_SET: unordered set of ASs a route in the
                               UPDATE message has traversed

                  2         AS_SEQUENCE: ordered set of ASs a route in
                               the UPDATE message has traversed

            The path segment length is a 1-octet long field containing
            the number of ASs in the path segment value field.

            The path segment value field contains one or more AS
            numbers, each encoded as a 2-octets long field.

            Usage of this attribute is defined in 5.1.2.

So, for example an UPDATE that contained a value of 7 for the Segment Type
when only 1-4 are defined (1-2 are defined here, 3-4 are defined in the
confed rfc) would generate a NOTIFICATION with the Malformed AS_PATH subcode.

There was a discussion on this list a while ago about what to do with a
specific type of malformed AS_PATH seen in the field.  A peer was sending
an AS_PATH with confed information in it to a non-confed peer.  Which 
constitutes a Malformed AS_PATH.

Andrew

On Sun, Aug 26, 2001 at 03:34:56PM +0200, Katia Linker <[email-masked]> wrote:

> Hi !
> I didn't understand from the RFC what is the case
> when update msg error subcode is MALFORMED AS PATH ?
>    Waiting for your help
>         Thanks in advance
>                Katya

From: Katia Linker <[email-masked]>
To: "[email-masked]'" <[email-masked]>
Subject: UPDATE msg error handling
Date: Sun, 26 Aug 2001 15:34:56 +0200
Sender: [email-masked]

Hi !
I didn't understand from the RFC what is the case
when update msg error subcode is MALFORMED AS PATH ?
   Waiting for your help
        Thanks in advance
               Katya

From: [email-masked]
To: [email-masked]
Subject: Call for Papers -- Passive & Active Measurement 2002
Date: Fri, 24 Aug 2001 09:18:38 -0700
Sender: [email-masked]

[Our apologies if you receive multiple copies of this CFP.  A more
detailed version of this CFP can be found on the conference web site
at http://www.labs.agilent.com/pam2002/papers/index.htm ]

             Passive & Active Measurement:  PAM 2002
                         Call for Papers

                    Fort Collins, Colorado, USA
                        March 25-27, 2002

PAM 2002 is a two-and-a-half day event focusing on research and practical
applications of passive and active measurement and analysis techniques
for high speed computer networks and the Internet.  This third PAM
workshop follows successful PAM workshops in Hamilton, New Zealand, in
2000 and Amsterdam, in 2001.

Papers are invited from the research, provider and any other communities
on topics related to network traffic measurement.  Areas of interest
include, but are not limited to:

1. 'Experience' papers, which describe practical uses of measurements,
   especially in large networks.
2. Papers on modelling network traffic, in particular if they are 
   backed up by measurements of real traffic.
3. Papers describing network research that can be applied to existing
   networks.

IMPORTANT DATES

 * 28 October 2001:   Deadline for abstracts
 * 3 December 2001:   Notification of acceptance
 * 4 February 2002:   Final papers due
 * 25-27 March 2002:  Conference

CONTACT INFORMATION

 * PAM 2002
   c/o Agilent Laboratories
   4800 Wheaton Dr
   Fort Collins, CO  80525
   USA
 * Phone:   +1-970-288-3821
 * Fax:     +1-970-288-4234
 * Email:   [email-masked]
 * Webpage: http://www.labs.agilent.com/pam2002

To: Jeffrey Haas <[email-masked]>
Cc: [email-masked]
Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt 
Date: Thu, 23 Aug 2001 15:05:50 -0700
From: Enke Chen <[email-masked]>
Sender: [email-masked]

> Date: Thu, 23 Aug 2001 17:40:19 -0400
> From: Jeffrey Haas <[email-masked]>
> To: Enke Chen <[email-masked]>, [email-masked]
> Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt
> Message-ID: <[email-masked]>
> References: <[email-masked]> <[email-masked]> <[email-masked]>
> Mime-Version: 1.0
>
> On Thu, Aug 23, 2001 at 05:35:38PM -0400, Jeffrey Haas wrote:
> > But what happens when we add the Next Greatest Thing that we also want
> > to stuff as much as possible in the path attributes?
> > 
> > "Should" still lets us do this.
> 
> That didn't come out right.
> 
> "Should" would still let us reorder things, but only if the implementor
> wanted to.

That seems to be equivalent to "optional" that I was suggesting.

In any case it is ok as long as the attribute ordering is not required,
even if the text is not fixed in the spec.. We probably have spent more
time than necessary on this thread.

-- Enke

Date: Thu, 23 Aug 2001 17:40:19 -0400
From: Jeffrey Haas <[email-masked]>
To: Enke Chen <[email-masked]>, [email-masked]
Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt
Sender: [email-masked]

On Thu, Aug 23, 2001 at 05:35:38PM -0400, Jeffrey Haas wrote:
> But what happens when we add the Next Greatest Thing that we also want
> to stuff as much as possible in the path attributes?
> 
> "Should" still lets us do this.

That didn't come out right.

"Should" would still let us reorder things, but only if the implementor
wanted to.

-- 
Jeff Haas 
NextHop Technologies

Date: Thu, 23 Aug 2001 17:35:38 -0400
From: Jeffrey Haas <[email-masked]>
To: Enke Chen <[email-masked]>, [email-masked]
Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt
Sender: [email-masked]

On Thu, Aug 23, 2001 at 01:51:01PM -0700, Enke Chen wrote:
> This "SHOULD/RECOMMENED" no longer makes sense with the introduction of
> MP_REACH and MP_UNREACH (see my original message). Is there any reason
> that we should continue this recommendation?

I would suspect that the real gist of your argument is that its easier
to serialize path attributes that have things like MP*NLRI in them
by putting the fixed things at the start of the path attributes and
then serializing as many NLRI as you can.  This does simplify your code
quite a bit.

But what happens when we add the Next Greatest Thing that we also want
to stuff as much as possible in the path attributes?

"Should" still lets us do this.

Note that the people I work with would be just as happy to relax this 
requirement, but I would rather people think about why we're relaxing it
in the first place.  I also like the idea that packets look relatively
consistant from one vendor implementation to another.

> -- Enke

-- 
Jeff Haas 
NextHop Technologies

To: Jeffrey Haas <[email-masked]>
Cc: [email-masked], [email-masked]
Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt 
Date: Thu, 23 Aug 2001 13:51:01 -0700
From: Enke Chen <[email-masked]>
Sender: [email-masked]

> Date: Thu, 23 Aug 2001 13:27:02 -0400
> From: Jeffrey Haas <[email-masked]>
> To: Enke Chen <[email-masked]>, [email-masked]
> Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt
> Message-ID: <[email-masked]>
> References: <[email-masked]>
>
> On Wed, Aug 22, 2001 at 11:15:19AM -0700, Enke Chen wrote:
> > The requirement on attribute ordering no longer makes sense with the
> > MP_* attributes as they contain NLRI but with values inbetween other
> > true attributes. In addition, the requirement does not reflect
> > the reality (deployed codes) AFAIK.
> > 
> > As the receiver is always required to deal with out of order attributes,
> > the attribute ordering requirement is not really necessary, and is
> > safe to relax.
> 
> And here's the original text:
> 
> > !    The sender of an UPDATE message should order path attributes within
> > !    the UPDATE message in ascending order of attribute type.  The
> 
> In the spirit of RFC 2119, I don't think we need to alter this text:
> 
> : 3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
> :    may exist valid reasons in particular circumstances to ignore a
> :    particular item, but the full implications must be understood and
> :    carefully weighed before choosing a different course.

This "SHOULD/RECOMMENED" no longer makes sense with the introduction of
MP_REACH and MP_UNREACH (see my original message). Is there any reason
that we should continue this recommendation?

-- Enke

Date: Thu, 23 Aug 2001 13:56:23 -0400
From: Jeffrey Haas <[email-masked]>
To: Eric Gray <[email-masked]>, [email-masked]
Subject: Re: re-posting a message
Sender: [email-masked]

On Thu, Aug 23, 2001 at 01:45:26PM -0400, Eric Gray wrote:
>     I believe that the reference to RFC 2385 is with respect to text
> about an "authentication scheme used by the transport protocol",
> rather than "BGP's own authentication mechanisms."

Sorry, I was responding to the underlined section, thus:

> > >    acknowledgment, and sequencing.  Any authentication scheme used by
> > >    the transport protocol may be used in addition to BGP's own
> > >    authentication mechanisms.  The error notification mechanism used in
> > > // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > // Reference to RFC2385 here?

So, something along the lines of:

Any authentication scheme used by the transport protocol, such as
RFC 2385 or IP-Sec, may be used in addition to BGP's own authentication
mechanisms.

I would be hesitant to actually specify any of these mechanisms. 
I believe it implies the blessing of the protocol.
I also thought we wanted 2385 to go away.

> Eric Gray

-- 
Jeff Haas 
NextHop Technologies

Date: Thu, 23 Aug 2001 13:45:26 -0400
From: Eric Gray <[email-masked]>
To: Jeffrey Haas <[email-masked]>
Cc: [email-masked]
Subject: Re: re-posting a message
Sender: [email-masked]

Jeff,

    I believe that the reference to RFC 2385 is with respect to text
about an "authentication scheme used by the transport protocol",
rather than "BGP's own authentication mechanisms."

    That being the case, the reference adds to information content
rather than noise, and would be appropriate.

--
Eric Gray

You wrote:

> On Fri, Aug 17, 2001 at 05:30:06AM -0700, Yakov Rekhter wrote:
> >    BGP runs over a reliable transport protocol.  This eliminates the
> >    need to implement explicit update fragmentation, retransmission,
> >    acknowledgment, and sequencing.  Any authentication scheme used by
> >    the transport protocol may be used in addition to BGP's own
> >    authentication mechanisms.  The error notification mechanism used in
> > // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > // Reference to RFC2385 here?
>
> I'm not certain referring to 2385 is appropriate.  While 2385 was
> crafted for protecting bgp peering sessions, it doesn't affect anything
> at the bgp protocol layer - i.e. the md5 signatures do not show up in
> the marker field in the bgp header.
>
> Does anyone actually _use_ the marker field?
>
> --
> Jeff Haas
> NextHop Technologies

Date: Thu, 23 Aug 2001 13:27:02 -0400
From: Jeffrey Haas <[email-masked]>
To: Enke Chen <[email-masked]>, [email-masked]
Subject: Re: Another suggestion for draft-ietf-idr-bgp4-12.txt
Sender: [email-masked]

On Wed, Aug 22, 2001 at 11:15:19AM -0700, Enke Chen wrote:
> The requirement on attribute ordering no longer makes sense with the
> MP_* attributes as they contain NLRI but with values inbetween other
> true attributes. In addition, the requirement does not reflect
> the reality (deployed codes) AFAIK.
> 
> As the receiver is always required to deal with out of order attributes,
> the attribute ordering requirement is not really necessary, and is
> safe to relax.

And here's the original text:

> !    The sender of an UPDATE message should order path attributes within
> !    the UPDATE message in ascending order of attribute type.  The

In the spirit of RFC 2119, I don't think we need to alter this text:

: 3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
:    may exist valid reasons in particular circumstances to ignore a
:    particular item, but the full implications must be understood and
:    carefully weighed before choosing a different course.

-- 
Jeff Haas 
NextHop Technologies

Date: Thu, 23 Aug 2001 13:14:15 -0400
From: Jeffrey Haas <[email-masked]>
To: [email-masked]
Subject: Re: re-posting a message
Sender: [email-masked]

On Fri, Aug 17, 2001 at 05:30:06AM -0700, Yakov Rekhter wrote:
>    BGP runs over a reliable transport protocol.  This eliminates the
>    need to implement explicit update fragmentation, retransmission,
>    acknowledgment, and sequencing.  Any authentication scheme used by
>    the transport protocol may be used in addition to BGP's own
>    authentication mechanisms.  The error notification mechanism used in
> // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> // Reference to RFC2385 here?

I'm not certain referring to 2385 is appropriate.  While 2385 was
crafted for protecting bgp peering sessions, it doesn't affect anything
at the bgp protocol layer - i.e. the md5 signatures do not show up in
the marker field in the bgp header.

Does anyone actually _use_ the marker field?

-- 
Jeff Haas 
NextHop Technologies

Reply-To: "Manav Bhatia" <[email-masked]>
From: "Manav Bhatia" <[email-masked]>
To: "Katia Linker" <[email-masked]>
Cc: <[email-masked]>
Subject: Re:Multiple prefixes in NLRI of UPDATE message
Date: Thu, 23 Aug 2001 09:33:57 +0530
Organization: Samsung India Operations
Sender: [email-masked]

This is a multi-part message in MIME format.

------=_NextPart_000_01AA_01C12BB6.BBE65040
Content-Type: text/plain;
	charset="windows-1255"
Content-Transfer-Encoding: quoted-printable

Hi Katia,
Generally when you send update messages to your neighbor the attributes =
AS path/nexthop do not change with different address prefixes. Say you =
are sending some updates to your EBGP peers .. in that case for all of =
the routes your AS path will be the same (unless you have some policy =
configured) and your next hop will also be the same i.e you =
yourself(once again unless you have some policy configured). So to save =
space you pack the bundle into one UPDATE message and push it off. You =
can achieve maximum compression when all the address prefixes also share =
the common attributes making it possible to send as many address =
prefixes as can fit the max sized BGP packet.

On the other hand if you do not advertise multiple address prefixes into =
one message then there is going to be huge traffic on your links once =
when the peers come up. To avoid this there is then added complexity of =
reducing your advertising rates, adding jitter and so on and so forth. =
This increases your convergence time and it has its set of related =
problems.

Hope it helps.

Regards,
Manav

----- Original Message -----=20
From: "Katia Linker" <[email-masked]>
To: <[email-masked]>
Sent: Wednesday, August 22, 2001 7:02 PM
Subject: Multiple prefixes in NLRI of UPDATE message

> Hi !
> Regards appendix 6.1 of RFC 1771, why they are talking=20
> only about AS path and next hop attributes that should be the same
> in order to send multiple address prefixes in one UPDATE message,
> and not also about all the other attributes.
> Waiting for your reply,
>  Thanks
>     Katya=20

------=_NextPart_000_01AA_01C12BB6.BBE65040
Content-Type: text/html;
	charset="windows-1255"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content=3D"text/html; charset=3Dwindows-1255" =
http-equiv=3DContent-Type>
<META content=3D"MSHTML 5.00.3103.1000" name=3DGENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2><EM>Hi Katia,</EM></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><EM>Generally when you send update =
messages to your=20
neighbor the attributes AS path/nexthop&nbsp;do not change with =
different=20
address prefixes. Say you are sending some updates to your EBGP peers .. =
in that=20
case for all of the routes your AS path will be the same (unless you =
have some=20
policy configured) and your next hop will also be the same i.e you =
yourself(once=20
again unless you have some policy configured). So to save space you=20
pack&nbsp;the bundle into one UPDATE message and push it off.&nbsp;You =
can=20
achieve maximum compression&nbsp;when all the address prefixes also =
share the=20
common attributes&nbsp;making it possible to send as many address =
prefixes as=20
can fit the max sized BGP packet.</EM></FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><EM>On the other hand if you do not =
advertise=20
multiple address prefixes into one message then there is going to be =
huge=20
traffic on your links once when the peers come up. To avoid this there =
is then=20
added complexity of reducing your advertising rates, adding jitter and =
so on and=20
so forth. This increases your convergence time and it has its set of =
related=20
problems.</EM></FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><EM>Hope it helps.</EM></FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><EM>Regards,</EM></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><EM>Manav</EM></FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><EM>----- Original Message ----- =
</EM></FONT></DIV>
<DIV>
<DIV><FONT face=3DArial size=3D2><EM>From: "Katia Linker" =
&lt;</EM></FONT><A=20
href=3D"mailto:[email-masked]"><FONT face=3DArial=20
size=3D2><EM>[email-masked]</EM></FONT></A><FONT face=3DArial=20
size=3D2><EM>&gt;</EM></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><EM>To: &lt;</EM></FONT><A=20
href=3D"mailto:[email-masked]"><FONT face=3DArial=20
size=3D2><EM>[email-masked]</EM></FONT></A><FONT face=3DArial=20
size=3D2><EM>&gt;</EM></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><EM>Sent: Wednesday, August 22, 2001 =
7:02=20
PM</EM></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><EM>Subject: Multiple prefixes in NLRI =
of UPDATE=20
message</EM></FONT></DIV></DIV>
<DIV><BR></DIV><FONT face=3DArial size=3D2><EM>&gt; Hi !<BR>&gt; Regards =
appendix=20
6.1 of RFC 1771, why they are talking <BR>&gt; only about AS path and =
next hop=20
attributes that should be the same<BR>&gt; in order to send multiple =
address=20
prefixes in one UPDATE message,<BR>&gt; and not also about all the other =

attributes.<BR>&gt; Waiting for your reply,<BR>&gt; &nbsp;Thanks<BR>&gt; =

&nbsp;&nbsp;&nbsp; Katya</EM></FONT> </BODY></HTML>

------=_NextPart_000_01AA_01C12BB6.BBE65040--

_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com

To: Katia Linker <[email-masked]>
Cc: "[email-masked]'" <[email-masked]>
Subject: Re: Multiple prefixes in NLRI of UPDATE message 
Date: Wed, 22 Aug 2001 11:21:44 -0700
From: Enke Chen <[email-masked]>
Sender: [email-masked]

That is a bug in the spec, and is being fixed in the new version
(as pointed out in Alex's diff).

-- Enke

> Message-ID: <42AB6BE23C29D511831E0002B32024885BDA0B@MESSENGER>
> From: Katia Linker <[email-masked]>
> To: "[email-masked]'" <[email-masked]>
> Subject: Multiple prefixes in NLRI of UPDATE message
> Date: Wed, 22 Aug 2001 15:32:46 +0200
> 
> Hi !
> Regards appendix 6.1 of RFC 1771, why they are talking 
> only about AS path and next hop attributes that should be the same
> in order to send multiple address prefixes in one UPDATE message,
> and not also about all the other attributes.
> Waiting for your reply,
>  Thanks
>     Katya
> 

To: [email-masked], [email-masked]
Cc: [email-masked], [email-masked]
Subject: Another suggestion for draft-ietf-idr-bgp4-12.txt
Date: Wed, 22 Aug 2001 11:15:19 -0700
From: Enke Chen <[email-masked]>
Sender: [email-masked]

Hi, Yakov and Sue:
Please consider the attached diff for draft-ietf-idr-bgp4-12.txt.

The requirement on attribute ordering no longer makes sense with the
MP_* attributes as they contain NLRI but with values inbetween other
true attributes. In addition, the requirement does not reflect
the reality (deployed codes) AFAIK.

As the receiver is always required to deal with out of order attributes,
the attribute ordering requirement is not really necessary, and is
safe to relax.

Thanks. -- Enke

*** draft-ietf-idr-bgp4-12.txt.orig	Fri Aug 17 11:25:38 2001
--- draft-ietf-idr-bgp4-12.txt	Wed Aug 22 09:24:16 2001
***************
*** 1198,1205 ****
  RFC DRAFT                                                   January 2001

!    The sender of an UPDATE message should order path attributes within
!    the UPDATE message in ascending order of attribute type.  The
     receiver of an UPDATE message must be prepared to handle path
     attributes within the UPDATE message that are out of order.
  
--- 1198,1205 ----
  RFC DRAFT                                                   January 2001

!    It is entirely optional for the sender of an UPDATE message to order path
!    attributes within the UPDATE message in ascending order of attribute type.  The
     receiver of an UPDATE message must be prepared to handle path
     attributes within the UPDATE message that are out of order.

From: Katia Linker <[email-masked]>
To: "[email-masked]'" <[email-masked]>
Subject: Multiple prefixes in NLRI of UPDATE message
Date: Wed, 22 Aug 2001 15:32:46 +0200
Sender: [email-masked]

Hi !
Regards appendix 6.1 of RFC 1771, why they are talking 
only about AS path and next hop attributes that should be the same
in order to send multiple address prefixes in one UPDATE message,
and not also about all the other attributes.
Waiting for your reply,
 Thanks
    Katya

To: Enke Chen <[email-masked]>
Cc: [email-masked]
Subject: Re: Suggested changes to draft-ietf-idr-bgp4-12.txt 
Date: Sun, 19 Aug 2001 11:07:36 -0700
From: Yakov Rekhter <[email-masked]>
Sender: [email-masked]

Enke,

> Hi, Yakov and Sue:
> I would like to suggest the following two changes to the draft as the
> texts in these two places do not reflect reality (i.e., deployed codes
> AFAIK), and the requirements are not necessary.

In the absence of any negative comments by Sep 1, I'll incorporate the
changes you suggesting.

Yakov.

> 
> Thanks. -- Enke
> 
> *** draft-ietf-idr-bgp4-12.txt.orig     Fri Aug 17 11:25:38 2001
> --- draft-ietf-idr-bgp4-12.txt  Fri Aug 17 11:28:37 2001
> ***************
> *** 761,768 ****
>            The fourth high-order bit (bit 3) of the Attribute Flags octet
>            is the Extended Length bit.  It defines whether the Attribute
>            Length is one octet (if set to 0) or two octets (if set to 1).
> -          Extended Length may be used only if the length of the attribute
> -          value is greater than 255 octets.
>   
>            The lower-order four bits of the Attribute Flags octet are .
>            unused. They must be zero (and must be ignored when received).
> --- 761,766 ----
> ***************
> *** 2445,2451 ****
>      information reduction techniques (see 9.2.4.1) may optionally be
>      applied.
>   
> -    For the benefit of future support of inter-AS multicast capabilities,
>   
>   
>   
> --- 2443,2448 ----
> ***************
> *** 2457,2476 ****
>   
>   RFC DRAFT                                                   January 2001
>   
> - 
> -    a BGP speaker that participates in inter-AS multicast routing shall
> -    advertise a route it receives from one of its external peers and if
> -    it installs it in its Loc-RIB, it shall advertise it back to the peer
> -    from which the route was received. For a BGP speaker that does not
> -    participate in inter-AS multicast routing such an advertisement is
> -    optional. When doing such an advertisement, the NEXT_HOP attribute
> -    should be set to the address of the peer. An implementation may also
> -    optimize such an advertisement by truncating information in the
> -    AS_PATH attribute to include only its own AS number and that of the
> -    peer that advertised the route (such truncation requires the ORIGIN
> -    attribute to be set to INCOMPLETE).  In addition an implementation is
> -    not required to pass optional or discretionary path attributes with
> -    such an advertisement.
>   
>      When the updating of the Adj-RIBs-Out and the Forwarding Information
>      Base (FIB) is complete, the local BGP speaker shall run the external
>      update process of 9.2.2.
> --- 2448,2453 ----
> 

Date: Sat, 18 Aug 2001 19:45:39 -0400
From: Vijay Gill <[email-masked]>
To: [email-masked]
Subject: Re: [nsp] Monitoring BGP routes... (fwd)
Sender: [email-masked]

I totally spaced on this at london.

This is something that is very valuable to service providers.

Currently using ssh and expect to monitor this but we'd like
something tied into our SNMP monitoring systems.  Another
nice feature would be the ability to send a trap if some
user defined limits are tripped.

fyi

/vijay

---------- Forwarded Message ----------
Date: Wednesday, July 04, 2001 2:08 PM +0200
From: Simon Leinen <[email-masked]>
To: Philip Smith <[email-masked]>
Subject: Re: [nsp] Monitoring BGP routes...

Cisco (or any other router vendor) could certainly do us a favor by
implementing SNMP objects for the following in their
enterprise-specific MIBs:

  total number of paths in the RIB
  per-neighbor number of paths in the RIB

Then it would be very easy to write tools that look at these, either
MRTG-like (useful to follow long-term trends in the number of routes
seem per BGP neighbor), or threshold-monitoring ones.

If people (other than me :-) start using these, then that would be a
good case for inclusion in future versions of the BGP MIB.  Note that
the BGP MIB is currently being revised, and there are several
Internet-Drafts up for comments, so this would be a good time to try
to get things like this in.

Maybe the SNMP-purists' opinion is that these objects aren't necessary
because they can be derived from existing tables, but as other people
have stated, counting entries in large tables is resource-intensive.
And the mechanisms that would make these operations tractable (such as
DISMAN agents local to routers) aren't really available yet.
-- 
Simon Leinen				       [email-masked]
SWITCH				   http://www.switch.ch/misc/leinen/

	       Computers hate being anthropomorphized.

---------- End Forwarded Message ----------

To: [email-masked], [email-masked]
Cc: [email-masked], [email-masked]
Subject: Suggested changes to draft-ietf-idr-bgp4-12.txt
Date: Fri, 17 Aug 2001 13:31:09 -0700
From: Enke Chen <[email-masked]>
Sender: [email-masked]

Hi, Yakov and Sue:
I would like to suggest the following two changes to the draft as the
texts in these two places do not reflect reality (i.e., deployed codes
AFAIK), and the requirements are not necessary.

Thanks. -- Enke

*** draft-ietf-idr-bgp4-12.txt.orig     Fri Aug 17 11:25:38 2001
--- draft-ietf-idr-bgp4-12.txt  Fri Aug 17 11:28:37 2001
***************
*** 761,768 ****
           The fourth high-order bit (bit 3) of the Attribute Flags octet
           is the Extended Length bit.  It defines whether the Attribute
           Length is one octet (if set to 0) or two octets (if set to 1).
-          Extended Length may be used only if the length of the attribute
-          value is greater than 255 octets.
  
           The lower-order four bits of the Attribute Flags octet are .
           unused. They must be zero (and must be ignored when received).
--- 761,766 ----
***************
*** 2445,2451 ****
     information reduction techniques (see 9.2.4.1) may optionally be
     applied.
  
-    For the benefit of future support of inter-AS multicast capabilities,

  
--- 2443,2448 ----
***************
*** 2457,2476 ****
  
  RFC DRAFT                                                   January 2001
  
- 
-    a BGP speaker that participates in inter-AS multicast routing shall
-    advertise a route it receives from one of its external peers and if
-    it installs it in its Loc-RIB, it shall advertise it back to the peer
-    from which the route was received. For a BGP speaker that does not
-    participate in inter-AS multicast routing such an advertisement is
-    optional. When doing such an advertisement, the NEXT_HOP attribute
-    should be set to the address of the peer. An implementation may also
-    optimize such an advertisement by truncating information in the
-    AS_PATH attribute to include only its own AS number and that of the
-    peer that advertised the route (such truncation requires the ORIGIN
-    attribute to be set to INCOMPLETE).  In addition an implementation is
-    not required to pass optional or discretionary path attributes with
-    such an advertisement.
  
     When the updating of the Adj-RIBs-Out and the Forwarding Information
     Base (FIB) is complete, the local BGP speaker shall run the external
     update process of 9.2.2.
--- 2448,2453 ----

Date: Fri, 17 Aug 2001 10:29:36 -0400
From: Eric Gray <[email-masked]>
To: [email-masked]
Cc: Yakov Rekhter <[email-masked]>
Subject: Re: re-posting a message
Sender: [email-masked]

Alex,

    Doing a little re-posting (or is it riposting), myself.
Apparently my prior post bounced.  See comments in-line below...

> ...
>
> Expiration Date October 2000                                    [Page 2]
>
> RFC DRAFT                                                     April 2000
>
>    reflects the "hop-by-hop" routing paradigm generally used throughout
>    the current Internet.  Note that some policies cannot be supported by
>    the "hop-by-hop" routing paradigm and thus require techniques such as
>    source routing to enforce.  For example, BGP does not enable one AS
>    to send traffic to a neighboring AS intending that the traffic take a
>    different route from that taken by traffic originating in the
>    neighboring AS.  On the other hand, BGP can support any policy
>    conforming to the "hop-by-hop" routing paradigm.  Since the current
>    Internet uses only the "hop-by-hop" routing paradigm and since BGP
>    can support any policy that conforms to that paradigm, BGP is highly
>    applicable as an inter-AS routing protocol for the current Internet.
>
> // The last sentence is not entirely correct anymore (i.e., MPLS TE is
> // there) I think it can be changed to say hop-by-hope inter-AS routing.

Freudian?  Okay as "... hop-by-hop inter-AS ..." - otherwise, it is routing
by leap of faith...

>
>
>    ...
>
> Expiration Date October 2000                                    [Page 3]
>
> RFC DRAFT                                                     April 2000
>
>    planned to explore various aspects of BGP application.  Please send
>    comments to the BGP mailing list ([email-masked]).
> //                                  ^^^^^^^^^^^^^^->"[email-masked]"?

Likewise guaranteed to be obsolete eventually - possibly better to omit?

>
>
> ...
>
> 5.1.3 NEXT_HOP
>
>    The NEXT_HOP path attribute defines the IP address of the border
>    router that should be used as the next hop to the destinations listed
>    in the UPDATE message.  When advertising a NEXT_HOP attribute to an
>
> Expiration Date October 2000                                   [Page 22]
>
> RFC DRAFT                                                     April 2000
>
>    external peer, a router may use one of its own interface addresses in
>    the NEXT_HOP attribute provided the external peer to which the route
>    is being advertised shares a common subnet with the NEXT_HOP address.
>    This is known as a "first party" NEXT_HOP attribute.  A BGP speaker
>    can advertise to an external peer an interface of any internal peer
>    router in the NEXT_HOP attribute provided the external peer to which
>    the route is being advertised shares a common subnet with the
>    NEXT_HOP address.  This is known as a "third party" NEXT_HOP
>    attribute. A BGP speaker can advertise any adjacent router in the
>    NEXT_HOP attribute provided that the IP address of this router was
>    learned from an external peer and the external peer to which the
>    route is being advertised shares a common subnet with the NEXT_HOP
>    address. This is a second form of "third party" NEXT_HOP attribute.
>
> /* Reword the above as follows:
>
>    The NEXT_HOP path attribute defines the IP address of the border
>    router that should be used as the next hop to the destinations listed
>    in the UPDATE message. The NEXT_HOP attribute is calculated as follows.
>
>      1) When sending a message to an internal peer, the BGP speaker
>         should not modify the NEXT_HOP attribute, unless it has been
>         explicitly configured to announce its own IP address as the
>         NEXT_HOP.

This is more than a rewording - this text does not appear to be either
explicit or implicit in the text being re-worded (which seems to talk
about advertisements to _external_ peers only).  Not that it is wrong,
as far as I can tell, but it is added text rather than reworded text.

>
>
>      2) When sending a message to an external peer X:
>
>         o If the route being announced was learned from an internal
>           peer or is locally originated, the BGP speaker can use for
>           the NEXT_HOP attribute an inerface address of the internal

... interface address ...

>
>           peer router through which the announced network is reachable
>           for the speaker, provided that peer X shares a common subnet
>           with this address. This is known as a "third party" NEXT_HOP
>           attribute.

Might be better to say "This is a form of 'third party' NEXT_HOP attribute."

>
>
>         o If the route being announced was learned from an external
>           peer, the speaker can use in the NEXT_HOP attribute an
>           IP address of any adjacent router (known from the received
>           NEXT_HOP attribute) that the speaker itself uses for local
>           route calculation, provided that peer X shares a common
>           subnet with this address. This is a second form of "third
>           party" NEXT_HOP attribute.
>
>         o If the external peer to which the route is being advertised
>           shares a common subnet with one of the announcing router's
>           own interfaces, the router may use the IP address associated
>           with such an interface in the NEXT_HOP attribute. This is known
>           as a "first party" NEXT_HOP attribute.
>
>         o By default (if none of the above conditions apply), the BGP
>           speaker should use in the NEXT_HOP attribute the IP address
>           that is used to establish the BGP session.
>
> */
>
>    Normally the NEXT_HOP attribute is chosen such that the shortest
>    available path will be taken.  A BGP speaker must be able to support
>    disabling advertisement of third party NEXT_HOP attributes to handle
>    imperfectly bridged media.
>
>    A BGP speaker must never advertise an address of a peer to that peer
>    as a NEXT_HOP, for a route that the speaker is originating.  A BGP
>    speaker must never install a route with itself as the next hop.
>
>    When a BGP speaker advertises the route to an internal peer, the
>    advertising speaker should not modify the NEXT_HOP attribute
>    associated with the route.
>
> // This part is covered above, so should be removed.

I believe you refer to the text I pointed out as being added, correct?
In that case, 'this part' should refer only to the paragraph immediately
above - is that right?

>
>                                When a BGP speaker receives the route via
>    an internal link, it may forward packets to the NEXT_HOP address if
>    the address contained in the attribute is on a common subnet with the
>    local and remote BGP speakers.
>
> /* Change to:
>
>    The NEXT_HOP attribute is used by the BGP speaker to determine the
>    actual outbound interface and immediate next-hop address that should be
>    used to forward transit packets to the associated destinations.
>    The immediate next-hop address is determined by performing a recursive
>    route lookup operation for the IP address in the NEXT_HOP attribute using
>    the contents of the Routing Table (see Section 9.1.2.1). The resolving
>    route will always specify the outbound interface. If the resolving route
>    specifies the next-hop address, this address should be used as
>    the immediate address for packet forwarding. If the address in
>    the NEXT_HOP attribute is directly resolved through a route to an attached
>    subnet (such a route will not specify the next-hop address), the outbound
>    interface should be taken from the resolving route and the address in
>    the NEXT_HOP attribute should be used as the immediate next-hop address.
>
> */
>
> 5.1.4   MULTI_EXIT_DISC
>
>    The MULTI_EXIT_DISC attribute may be used on external (inter-AS)
>    links to discriminate among multiple exit or entry points to the same
>    neighboring AS.  The value of the MULTI_EXIT_DISC attribute is a four
>    octet unsigned number which is called a metric.  All other factors
>    being equal, the exit or entry point with lower metric should be
> //                  ^^^^^^^^^^^^^ this should be just entry point

I don't understand this one.  I would have thought 'just exit' would make
more sense, if you were going to get rid of one or the other.  Also, if
you get rid of one here, why would you leave it at the beginning of the
paragraph?

>
>
>    preferred.  If received over external links, the MULTI_EXIT_DISC
>    attribute MAY be propagated over internal links to other BGP speakers
>    within the same AS.  The MULTI_EXIT_DISC attribute received from a
>    neighboring AS MUST NOT be propagated to other neighboring ASs.
>
>    A BGP speaker MUST IMPLEMENT a mechanism based on local configuration
>    which allows the MULTI_EXIT_DISC attribute to be removed from a
>    route.  This MAY be done either prior to or after determining the
>    degree of preference of the route and performing route selection
>
> // I believe the above should say only "prior". Otherwise, we can
> // have inconsistent decisions in the same AS.

I think this is satisfied if the 'mechanism based on local configuration'
establishes a consistent decision point within an AS.

>
>
> ...
>
>          In response to the ConnectRetry timer expired event, the local
>          system restarts the ConnectRetry timer, initiates a transport
>          connection to other BGP peer, continues to listen for a
> //                     ^^^^^->"the" ?

other => the

>
>
> ...
>
>          In response to the ConnectRetry timer expired event, the local
>          system restarts the ConnectRetry timer, initiates a transport
>          connection to other BGP peer, continues to listen for a
> //                     ^^^^^->"the"?

other => the

>
>
> ...
>
>          If there are no errors in the OPEN message, BGP sends a
>          KEEPALIVE message and sets a KeepAlive timer.  The Hold Timer,
>          which was originally set to a large value (see above), is
>          replaced with the negotiated Hold Time value (see section 4.2).
>          If the negotiated Hold Time value is zero, then the Hold Time
>          timer and KeepAlive timers are not started.  If the value of
>          the Autonomous System field is the same as the local Autonomous
>          System number, then the connection is an "internal" connection;
>          otherwise, it is "external".  (This will effect UPDATE
> //                                                ^^^^^^->"affect"?

Valid either way, though 'effect' is closer because it more directly
relates to cause.

(See meaning 1 @ http://www.dictionary.com/cgi-bin/dict.pl?term=affect
and meaning 2 @ http://www.dictionary.com/cgi-bin/dict.pl?term=effect

>
> ...
>
>       - In order to achieve successful distributed operation, only
>       routes with a likelihood of stability can be chosen.  Thus, an AS
>       must avoid using unstable routes, and it must not make rapid
>       spontaneous changes to its choice of route.  Quantifying the terms
>       "unstable" and "rapid" in the previous sentence will require
>       experience, but the principle is clear.
>
> // Care must be taken to ensure that BGP speakers in the same AS do
> // not make inconsistent decisions.

Is this an editorial comment, or are you proposing to add this text?

>
>
> ...
>
> - --
> Alex Zinin
>
> ---

--
Eric Gray

To: [email-masked]
Subject: re-posting a message
Date: Fri, 17 Aug 2001 05:30:06 -0700
From: Yakov Rekhter <[email-masked]>
Sender: [email-masked]

fyi (please remember that the deadline for comments on the attached
is Sep 1). In the absence of any negative comments, the changes suggested
in the attached will be incorporated into the next revision of the
BGP draft.

Yakov.
------- Forwarded Message

Date:    Fri, 10 Aug 2001 08:37:15 +0100
From:    Alex Zinin <[email-masked]>
To:      Yakov Rekhter <[email-masked]>, [email-masked]
Subject: Fwd: Reposting Suggested Changes

Yakov, Sue

 I've sent this message to the alias two times , but didn't see
 it flying by, even though I'm subscribed to both idr and idr-post.
 Anyways, I'll be traveling till 25th, so, please, fwd this appropriately.

 Cheers,
Alex.

This is a forwarded message
From: Alex Zinin <[email-masked]>
To: [email-masked]
Date: Thursday, August 09, 2001, 12:15:50 AM
Subject: Reposting Suggested Changes

===8<==============Original message text===============
Folks,

 As agreed at the IDR WG meeting today:
 
   a) I'm reposting suggested changes to the BGP spec (only generic ones;
      9.1.2-related ones seem to have gone through the discussion on the
      list and reached a mature state)
      
   b) an inactivity timer is started to facilitate the discussion process;
      the timer expires Sep 1st; if no comments are received by that
      time, the changes will be considered accepted by the WG.

 I'll be traveling till Aug 25th, so replies will be slow.
 
- -- 
Alex Zinin

Folks,

  Below are some more comments on the BGP spec
  (introduced as C comments).
  The new text is suggested in some places, others
  need a discussion.

  Cheers,
- -- 
Alex Zinin

2.  Introduction

   The Border Gateway Protocol (BGP) is an inter-Autonomous System
   routing protocol.  It is built on experience gained with EGP as
   defined in RFC 904 [1] and EGP usage in the NSFNET Backbone as
   described in RFC 1092 [2] and RFC 1093 [3].

   The primary function of a BGP speaking system is to exchange network
   reachability information with other BGP systems.  This network
   reachability information includes information on the list of
   Autonomous Systems (ASs) that reachability information traverses.
   This information is sufficient to construct a graph of AS
   connectivity from which routing loops may be pruned and some policy
   decisions at the AS level may be enforced.

   BGP-4 provides a new set of mechanisms for supporting classless
   interdomain routing.  These mechanisms include support for
   advertising an IP prefix and eliminates the concept of network
   "class" within BGP.  BGP-4 also introduces mechanisms which allow
   aggregation of routes, including aggregation of AS paths.  These
   changes provide support for the proposed supernetting scheme [8, 9].

   To characterize the set of policy decisions that can be enforced
   using BGP, one must focus on the rule that a BGP speaker advertise to
   its peers (other BGP speakers which it communicates with) in
   neighboring ASs only those routes that it itself uses.  This rule

Expiration Date October 2000                                    [Page 2]

RFC DRAFT                                                     April 2000

   reflects the "hop-by-hop" routing paradigm generally used throughout
   the current Internet.  Note that some policies cannot be supported by
   the "hop-by-hop" routing paradigm and thus require techniques such as
   source routing to enforce.  For example, BGP does not enable one AS
   to send traffic to a neighboring AS intending that the traffic take a
   different route from that taken by traffic originating in the
   neighboring AS.  On the other hand, BGP can support any policy
   conforming to the "hop-by-hop" routing paradigm.  Since the current
   Internet uses only the "hop-by-hop" routing paradigm and since BGP
   can support any policy that conforms to that paradigm, BGP is highly
   applicable as an inter-AS routing protocol for the current Internet.

// The last sentence is not entirely correct anymore (i.e., MPLS TE is
// there) I think it can be changed to say hop-by-hope inter-AS routing.

   A more complete discussion of what policies can and cannot be
   enforced with BGP is outside the scope of this document (but refer to
   the companion document discussing BGP usage [5]).

   BGP runs over a reliable transport protocol.  This eliminates the
   need to implement explicit update fragmentation, retransmission,
   acknowledgment, and sequencing.  Any authentication scheme used by
   the transport protocol may be used in addition to BGP's own
   authentication mechanisms.  The error notification mechanism used in
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// Reference to RFC2385 here?

   BGP assumes that the transport protocol supports a "graceful" close,
   i.e., that all outstanding data will be delivered before the
   connection is closed.

   BGP uses TCP [4] as its transport protocol.  TCP meets BGP's
   transport requirements and is present in virtually all commercial
   routers and hosts.  In the following descriptions the phrase
   "transport protocol connection" can be understood to refer to a TCP
   connection.  BGP uses TCP port 179 for establishing its connections.

   This document uses the term `Autonomous System' (AS) throughout.  The
   classic definition of an Autonomous System is a set of routers under
   a single technical administration, using an interior gateway protocol
   and common metrics to route packets within the AS, and using an
   exterior gateway protocol to route packets to other ASs.  Since this
   classic definition was developed, it has become common for a single
   AS to use several interior gateway protocols and sometimes several
   sets of metrics within an AS.  The use of the term Autonomous System
   here stresses the fact that, even when multiple IGPs and metrics are
   used, the administration of an AS appears to other ASs to have a
   single coherent interior routing plan and presents a consistent
   picture of what destinations are reachable through it.

   The planned use of BGP in the Internet environment, including such
   issues as topology, the interaction between BGP and IGPs, and the
   enforcement of routing policy rules is presented in a companion
   document [5].  This document is the first of a series of documents

Expiration Date October 2000                                    [Page 3]

RFC DRAFT                                                     April 2000

   planned to explore various aspects of BGP application.  Please send
   comments to the BGP mailing list ([email-masked]).
//                                  ^^^^^^^^^^^^^^->"[email-masked]"?

4.3 UPDATE Message Format
...
         d) MULTI_EXIT_DISC (Type Code 4):

            This is an optional non-transitive attribute that is a four
            octet non-negative integer. The value of this attribute may
            be used by a BGP speaker's decision process to discriminate
            among multiple exit points to a neighboring autonomous
            system.

//          I think the above should be "multiple _entry_ points",
//          we do not try to add our IGP distance to received MED.

            Its usage is defined in 5.1.4.

         e) LOCAL_PREF (Type Code 5):

            LOCAL_PREF is a well-known mandatory attribute that is a
            four octet non-negative integer. It is used by a BGP speaker
            to inform other internal peers of the advertising speaker's
            degree of preference for an advertised route. Usage of this
            attribute is described in 5.1.5.

         f) ATOMIC_AGGREGATE (Type Code 6)

            ATOMIC_AGGREGATE is a well-known discretionary attribute of
            length 0. It is used by a BGP speaker to inform other BGP
            speakers that the local system selected a less specific
            route without selecting a more specific route which is
            included in it. Usage of this attribute is described in

Expiration Date October 2000                                   [Page 15]

RFC DRAFT                                                     April 2000

            5.1.6.

         g) AGGREGATOR (Type Code 7)

            AGGREGATOR is an optional transitive attribute of length 6.
            The attribute contains the last AS number that formed the
            aggregate route (encoded as 2 octets), followed by the IP
            address of the BGP speaker that formed the aggregate route

// Per Jeffery, this should be the router ID

            (encoded as 4 octets).  Usage of this attribute is described
            in 5.1.7

      Network Layer Reachability Information:

         This variable length field contains a list of IP address
         prefixes.  The length in octets of the Network Layer
         Reachability Information is not encoded explicitly, but can be
         calculated as:

            UPDATE message Length - 23 - Total Path Attributes Length -
            Unfeasible Routes Length

         where UPDATE message Length is the value encoded in the fixed-
         size BGP header, Total Path Attribute Length and Unfeasible
         Routes Length  are the values encoded in the variable part of
         the UPDATE message, and 23 is a combined length of the fixed-
         size BGP header, the Total Path Attribute Length field and the
         Unfeasible Routes Length field.

         Reachability information is encoded as one or more 2-tuples of
         the form <length, prefix>, whose fields are described below:

                  +---------------------------+
                  |   Length (1 octet)        |
                  +---------------------------+
                  |   Prefix (variable)       |
                  +---------------------------+

         The use and the meaning of these fields are as follows:

         a) Length:

            The Length field indicates the length in bits of the IP
            address prefix. A length of zero indicates a prefix that
            matches all IP addresses (with prefix, itself, of zero
            octets).

Expiration Date October 2000                                   [Page 16]

RFC DRAFT                                                     April 2000

         b) Prefix:

            The Prefix field contains IP address prefixes followed by
            enough trailing bits to make the end of the field fall on an
            octet boundary. Note that the value of the trailing bits is
            irrelevant.

   The minimum length of the UPDATE message is 23 octets -- 19 octets
   for the fixed header + 2 octets for the Unfeasible Routes Length + 2
   octets for the Total Path Attribute Length (the value of Unfeasible
   Routes Length is 0  and the value of Total Path Attribute Length is
   0).

   An UPDATE message can advertise at most one route, which may be
   described by several path attributes. All path attributes contained
   in a given UPDATE messages apply to the destinations carried in the
   Network Layer Reachability Information field of the UPDATE message.

/* Change to:

   An UPDATE message can advertise at most one set of path attributes,
   but multiple destinations sharing these attributes. All path attributes
   contained in a given UPDATE messages apply to all destinations carried
   in the Network Layer Reachability Information field of the UPDATE message.

*/

   An UPDATE message can list multiple routes to be withdrawn from
   service.  Each such route is identified by its destination (expressed
   as an IP prefix), which unambiguously identifies the route in the
   context of the BGP speaker - BGP speaker connection to which it has
   been previously been advertised.
//                 ^^^^ remove this "been"

   An UPDATE message may advertise only routes to be withdrawn from
   service, in which case it will not include path attributes or Network
   Layer Reachability Information. Conversely, it may advertise only a
   feasible route, in which case the WITHDRAWN ROUTES field need not be
   present.

5.1.2   AS_PATH

   AS_PATH is a well-known mandatory attribute. This attribute

Expiration Date October 2000                                   [Page 21]

RFC DRAFT                                                     April 2000

   identifies the autonomous systems through which routing information
   carried in this UPDATE message has passed. The components of this
   list can be AS_SETs or AS_SEQUENCEs.

   When a BGP speaker propagates a route which it has learned from
   another BGP speaker's UPDATE message, it shall modify the route's
   AS_PATH attribute based on the location of the BGP speaker to which
   the route will be sent:

      a) When a given BGP speaker advertises the route to an internal
      peer, the advertising speaker shall not modify the AS_PATH
      attribute associated with the route.

      b) When a given BGP speaker advertises the route to an external
      peer, then the advertising speaker shall update the AS_PATH
      attribute as follows:

         1) if the first path segment of the AS_PATH is of type
         AS_SEQUENCE, the local system shall prepend its own AS number
         as the last element of the sequence  (put it in the leftmost
         position)

         2) if the first path segment of the AS_PATH is of type AS_SET,
         the local system shall prepend a new path segment of type
         AS_SEQUENCE to the AS_PATH, including its own AS number in that
         segment.

      When a BGP speaker originates a route then:

         a) the originating speaker shall include its own AS number in
         the AS_PATH attribute of all UPDATE messages sent to an
         external peer.  (In this case, the AS number of the originating
         speaker's autonomous system will be the only entry in the
         AS_PATH attribute).

         b) the originating speaker shall include an empty AS_PATH
         attribute in all UPDATE messages sent to internal peers.  (An
         empty AS_PATH attribute is one whose length field contains the
         value zero).

/* Add:

  For the purpose of inter-AS traffic engineering, a BGP speaker may be
  configured to include more than one instance of its own AS number in
  the AS_PATH attribute.

*/

5.1.3 NEXT_HOP

   The NEXT_HOP path attribute defines the IP address of the border
   router that should be used as the next hop to the destinations listed
   in the UPDATE message.  When advertising a NEXT_HOP attribute to an

Expiration Date October 2000                                   [Page 22]

RFC DRAFT                                                     April 2000

   external peer, a router may use one of its own interface addresses in
   the NEXT_HOP attribute provided the external peer to which the route
   is being advertised shares a common subnet with the NEXT_HOP address.
   This is known as a "first party" NEXT_HOP attribute.  A BGP speaker
   can advertise to an external peer an interface of any internal peer
   router in the NEXT_HOP attribute provided the external peer to which
   the route is being advertised shares a common subnet with the
   NEXT_HOP address.  This is known as a "third party" NEXT_HOP
   attribute. A BGP speaker can advertise any adjacent router in the
   NEXT_HOP attribute provided that the IP address of this router was
   learned from an external peer and the external peer to which the
   route is being advertised shares a common subnet with the NEXT_HOP
   address. This is a second form of "third party" NEXT_HOP attribute.

/* Reword the above as follows:

   The NEXT_HOP path attribute defines the IP address of the border
   router that should be used as the next hop to the destinations listed
   in the UPDATE message. The NEXT_HOP attribute is calculated as follows.

     1) When sending a message to an internal peer, the BGP speaker
        should not modify the NEXT_HOP attribute, unless it has been
        explicitly configured to announce its own IP address as the
        NEXT_HOP.       

     2) When sending a message to an external peer X:

        o If the route being announced was learned from an internal
          peer or is locally originated, the BGP speaker can use for
          the NEXT_HOP attribute an inerface address of the internal
          peer router through which the announced network is reachable
          for the speaker, provided that peer X shares a common subnet
          with this address. This is known as a "third party" NEXT_HOP
          attribute.

        o If the route being announced was learned from an external
          peer, the speaker can use in the NEXT_HOP attribute an
          IP address of any adjacent router (known from the received
          NEXT_HOP attribute) that the speaker itself uses for local
          route calculation, provided that peer X shares a common
          subnet with this address. This is a second form of "third
          party" NEXT_HOP attribute.

        o If the external peer to which the route is being advertised
          shares a common subnet with one of the announcing router's 
          own interfaces, the router may use the IP address associated
          with such an interface in the NEXT_HOP attribute. This is known
          as a "first party" NEXT_HOP attribute.  

        o By default (if none of the above conditions apply), the BGP
          speaker should use in the NEXT_HOP attribute the IP address
          that is used to establish the BGP session.

*/

   Normally the NEXT_HOP attribute is chosen such that the shortest
   available path will be taken.  A BGP speaker must be able to support
   disabling advertisement of third party NEXT_HOP attributes to handle
   imperfectly bridged media.

   A BGP speaker must never advertise an address of a peer to that peer
   as a NEXT_HOP, for a route that the speaker is originating.  A BGP
   speaker must never install a route with itself as the next hop.

   When a BGP speaker advertises the route to an internal peer, the
   advertising speaker should not modify the NEXT_HOP attribute
   associated with the route.  

// This part is covered above, so should be removed.

                               When a BGP speaker receives the route via
   an internal link, it may forward packets to the NEXT_HOP address if
   the address contained in the attribute is on a common subnet with the
   local and remote BGP speakers.

/* Change to:

   The NEXT_HOP attribute is used by the BGP speaker to determine the
   actual outbound interface and immediate next-hop address that should be
   used to forward transit packets to the associated destinations.
   The immediate next-hop address is determined by performing a recursive
   route lookup operation for the IP address in the NEXT_HOP attribute using
   the contents of the Routing Table (see Section 9.1.2.1). The resolving
   route will always specify the outbound interface. If the resolving route
   specifies the next-hop address, this address should be used as 
   the immediate address for packet forwarding. If the address in
   the NEXT_HOP attribute is directly resolved through a route to an attached
   subnet (such a route will not specify the next-hop address), the outbound
   interface should be taken from the resolving route and the address in
   the NEXT_HOP attribute should be used as the immediate next-hop address.

*/

5.1.4   MULTI_EXIT_DISC

   The MULTI_EXIT_DISC attribute may be used on external (inter-AS)
   links to discriminate among multiple exit or entry points to the same
   neighboring AS.  The value of the MULTI_EXIT_DISC attribute is a four
   octet unsigned number which is called a metric.  All other factors
   being equal, the exit or entry point with lower metric should be
//                  ^^^^^^^^^^^^^ this should be just entry point

   preferred.  If received over external links, the MULTI_EXIT_DISC
   attribute MAY be propagated over internal links to other BGP speakers
   within the same AS.  The MULTI_EXIT_DISC attribute received from a
   neighboring AS MUST NOT be propagated to other neighboring ASs.

   A BGP speaker MUST IMPLEMENT a mechanism based on local configuration
   which allows the MULTI_EXIT_DISC attribute to be removed from a
   route.  This MAY be done either prior to or after determining the
   degree of preference of the route and performing route selection

// I believe the above should say only "prior". Otherwise, we can
// have inconsistent decisions in the same AS.

Expiration Date October 2000                                   [Page 23]

RFC DRAFT                                                     April 2000

   (decision process phases 1 and 2).

   An implementation MAY also (based on local configuration) alter the
   value of the MULTI_EXIT_DISC attribute received over an external
   link.  If it does so, it shall do so prior to determining the degree
   of preference of the route and performing route selection (decision
   process phases 1 and 2).

5.1.5   LOCAL_PREF

   LOCAL_PREF is a well-known mandatory attribute that SHALL be included
   in all UPDATE messages that a given BGP speaker sends to the other
   internal peers. A BGP speaker SHALL calculate the degree of
   preference for each external route and include the degree of
//                                   ^+"based on locally configured policy"

   preference when advertising a route to its internal peers. The higher
   degree of preference MUST be preferred. A BGP speaker shall use the
   degree of preference learned via LOCAL_PREF in its decision process
   (see section 9.1.1).

   A BGP speaker MUST NOT include this attribute in UPDATE messages that
   it sends to external peers.  If it is contained in an UPDATE message
   that is received from an external peer, then this attribute MUST be
   ignored by the receiving speaker.

5.1.7   AGGREGATOR

   AGGREGATOR is an optional transitive attribute which may be included
   in updates which are formed by aggregation (see Section 9.2.4.2).  A
   BGP speaker which performs route aggregation may add the AGGREGATOR
   attribute which shall contain its own AS number and IP address.

// should be "AS number and the router ID" per Jeffrey.

6.3 UPDATE message error handling.

   All errors detected while processing the UPDATE message are indicated
   by sending the NOTIFICATION message with Error Code UPDATE Message
   Error.  The error subcode elaborates on the specific nature of the
   error.

   Error checking of an UPDATE message begins by examining the path
   attributes.  If the Unfeasible Routes Length or Total Attribute
   Length is too large (i.e., if Unfeasible Routes Length + Total
   Attribute Length + 23 exceeds the message Length), then the Error
   Subcode is set to Malformed Attribute List.

   If any recognized attribute has Attribute Flags that conflict with
   the Attribute Type Code, then the Error Subcode is set to Attribute
   Flags Error.  The Data field contains the erroneous attribute (type,
   length and value).

   If any recognized attribute has Attribute Length that conflicts with
   the expected length (based on the attribute type code), then the
   Error Subcode is set to Attribute Length Error.  The Data field
   contains the erroneous attribute (type, length and value).

   If any of the mandatory well-known attributes are not present, then
   the Error Subcode is set to Missing Well-known Attribute.  The Data
   field contains the Attribute Type Code of the missing well-known
   attribute.

   If any of the mandatory well-known attributes are not recognized,
   then the Error Subcode is set to Unrecognized Well-known Attribute.
   The Data field contains the unrecognized attribute (type, length and
   value).

   If the ORIGIN attribute has an undefined value, then the Error
   Subcode is set to Invalid Origin Attribute.  The Data field contains

Expiration Date October 2000                                   [Page 27]

RFC DRAFT                                                     April 2000

   the unrecognized attribute (type, length and value).

   If the NEXT_HOP attribute field is syntactically incorrect, then the
   Error Subcode is set to Invalid NEXT_HOP Attribute.  The Data field
   contains the incorrect attribute (type, length and value).  Syntactic
   correctness means that the NEXT_HOP attribute represents a valid IP
   host address.  Semantic correctness applies only to the external BGP
   links. It means that the interface associated with the IP address, as
   specified in the NEXT_HOP attribute, shares a common subnet with the
   receiving BGP speaker 

// Add: (unless the speakers have been explicitly configured to
// run the external BGP session through multiple hops) 

                        and is not the IP address of the receiving BGP
   speaker.  If the NEXT_HOP attribute is semantically incorrect, the
   error should be logged, and the the route should be ignored.  In this
//                             ^^^ remove
   case, no NOTIFICATION message should be sent.

   The AS_PATH attribute is checked for syntactic correctness.  If the
   path is syntactically incorrect, then the Error Subcode is set to
   Malformed AS_PATH.

   The information carried by the AS_PATH attribute is checked for AS
   loops. AS loop detection is done by scanning the full AS path (as
   specified in the AS_PATH attribute), and checking that the autonomous
   system number of the local system does not appear in the AS path. If
   the autonomous system number appears in the AS path the route may be
   stored in the Adj-RIB-In, but unless the router is configured to
   accept routes with its own autonomous system in the AS path, the
   route shall not be passed to the BGP Decision Process. Operations of
   a router that is configured to accept routes with its own autonomous
   system number in the AS path are outside the scope of this document.

   If an optional attribute is recognized, then the value of this
   attribute is checked.  If an error is detected, the attribute is
   discarded, and the Error Subcode is set to Optional Attribute Error.
   The Data field contains the attribute (type, length and value).

   If any attribute appears more than once in the UPDATE message, then
   the Error Subcode is set to Malformed Attribute List.

   The NLRI field in the UPDATE message is checked for syntactic
   validity.  If the field is syntactically incorrect, then the Error
   Subcode is set to Invalid Network Field.

// If a prefix in the NLRI field is semantically incorrect (e.g., an
// unexpected multicast IP address is received), an error should be
// logged locally and the prefix should be ignored.

   An UPDATE message that contains correct path attributes, but no NLRI,
   shall be treated as a valid UPDATE message.

Expiration Date October 2000                                   [Page 28]

RFC DRAFT                                                     April 2000

8.  BGP Finite State machine.

   This section specifies BGP operation in terms of a Finite State
   Machine (FSM).  Following is a brief summary and overview of BGP
   operations by state as determined by this FSM.  A condensed version
   of the BGP FSM is found in Appendix 1.

// I guess we miss the event description here.

      Initially BGP is in the Idle state.

      Idle state:

         In this state BGP refuses all incoming BGP connections.  No
         resources are allocated to the peer.  In response to the Start
         event (initiated by either system or operator) the local system
         initializes all BGP resources, starts the ConnectRetry timer,
         initiates a transport connection to other BGP peer, while
         listening for connection that may be initiated by the remote
         BGP peer, and changes its state to Connect.  The exact value of
         the ConnectRetry timer is a local matter, but should be
         sufficiently large to allow TCP initialization.

         If a BGP speaker detects an error, it shuts down the connection
         and changes its state to Idle. Getting out of the Idle state
         requires generation of the Start event.  If such an event is
         generated automatically, then persistent BGP errors may result
         in persistent flapping of the speaker.  To avoid such a
         condition it is recommended that Start events should not be
         generated immediately for a peer that was previously
         transitioned to Idle due to an error. For a peer that was
         previously transitioned to Idle due to an error, the time

Expiration Date October 2000                                   [Page 31]

RFC DRAFT                                                     April 2000

         between consecutive generation of Start events, if such events
         are generated automatically, shall exponentially increase. The
         value of the initial timer shall be 60 seconds. The time shall
         be doubled for each consecutive retry.

         Any other event received in the Idle state is ignored.

      Connect state:

         In this state BGP is waiting for the transport protocol
         connection to be completed.

         If the transport protocol connection succeeds, the local system
         clears the ConnectRetry timer, completes initialization, sends
         an OPEN message to its peer, and changes its state to OpenSent.

         If the transport protocol connect fails (e.g., retransmission
         timeout), the local system restarts the ConnectRetry timer,
         continues to listen for a connection that may be initiated by
         the remote BGP peer, and changes its state to Active state.

         In response to the ConnectRetry timer expired event, the local
         system restarts the ConnectRetry timer, initiates a transport
         connection to other BGP peer, continues to listen for a
//                     ^^^^^->"the" ?

         connection that may be initiated by the remote BGP peer, and
         stays in the Connect state.

         Start event is ignored in the Connect state.

         In response to any other event (initiated by either system or
         operator), the local system releases all BGP resources
         associated with this connection and changes its state to Idle.

      Active state:

         In this state BGP is trying to acquire a peer by listening for
         and accepting a transport protocol connection.

         If the transport protocol connection succeeds, the local system
         clears the ConnectRetry timer, completes initialization, sends
         an OPEN message to its peer, sets its Hold Timer to a large
         value, and changes its state to OpenSent.  A Hold Timer value
         of 4 minutes is suggested.

         In response to the ConnectRetry timer expired event, the local
         system restarts the ConnectRetry timer, initiates a transport
         connection to other BGP peer, continues to listen for a
//                     ^^^^^->"the"?

         connection that may be initiated by the remote BGP peer, and

Expiration Date October 2000                                   [Page 32]

RFC DRAFT                                                     April 2000

         changes its state to Connect.

         If the local system allows BGP connections with unconfigured
         peers, then when the local system detects that a remote peer is
         trying to establish a BGP connection to it, and the IP address
         of the remote peer is not a configured one, the local system
         creates a temporary peer entry, completes initialization, sends
         an OPEN message to its peer, sets its Hold Timer to a large
         value, and changes its state to OpenSent.

         If the local system does not allow BGP connections with
         unconfigured peers, then the local system rejects connections
         from IP addresses that are not configured peers, and remains in
         the Active state.

         Start event is ignored in the Active state.

         In response to any other event (initiated by either system or
         operator), the local system releases all BGP resources
         associated with this connection and changes its state to Idle.

      OpenSent state:

         In this state BGP waits for an OPEN message from its peer.
         When an OPEN message is received, all fields are checked for
         correctness.  If the BGP message header checking or OPEN
         message checking detects an error (see Section 6.2), or a
         connection collision (see Section 6.8) the local system sends a
         NOTIFICATION message and changes its state to Idle.

         If there are no errors in the OPEN message, BGP sends a
         KEEPALIVE message and sets a KeepAlive timer.  The Hold Timer,
         which was originally set to a large value (see above), is
         replaced with the negotiated Hold Time value (see section 4.2).
         If the negotiated Hold Time value is zero, then the Hold Time
         timer and KeepAlive timers are not started.  If the value of
         the Autonomous System field is the same as the local Autonomous
         System number, then the connection is an "internal" connection;
         otherwise, it is "external".  (This will effect UPDATE
//                                                ^^^^^^->"affect"?

         processing as described below.)  Finally, the state is changed
         to OpenConfirm.

...

9.1 Decision Process

   The Decision Process selects routes for subsequent advertisement by
   applying the policies in the local Policy Information Base (PIB) to
   the routes stored in its Adj-RIB-In. The output of the Decision
//                          ^^^^^^^^^^^->"Adj-RIBs-In"

   Process is the set of routes that will be advertised to all peers;
   the selected routes will be stored in the local speaker's Adj-RIB-
   Out.

   The selection process is formalized by defining a function that takes
   the attribute of a given route as an argument and returns a non-
   negative integer denoting the degree of preference for the route.
   The function that calculates the degree of preference for a given
   route shall not use as its inputs any of the following:  the
   existence of other routes, the non-existence of other routes, or the
   path attributes of other routes. Route selection then consists of
   individual application of the degree of preference function to each
   feasible route, followed by the choice of the one with the highest
   degree of preference.

   The Decision Process operates on routes contained in each Adj-RIB-In,
   and is responsible for:

// Add: - selection of routes to be used locally by the speaker

      - selection of routes to be advertised to internal peers

      - selection of routes to be advertised to external peers

      - route aggregation and route information reduction

   The Decision Process takes place in three distinct phases, each
   triggered by a different event:

      a) Phase 1 is responsible for calculating the degree of preference
      for each route received from an external peer, and MAY also
      advertise to  all the internal peers the routes from external
      peers that have the highest degree of preference for each distinct

Expiration Date October 2000                                   [Page 37]

RFC DRAFT                                                     April 2000

      destination.

      b) Phase 2 is invoked on completion of phase 1. It is responsible
      for choosing the best route out of all those available for each
      distinct destination, and for installing each chosen route into
      the appropriate Loc-RIB.

      c) Phase 3 is invoked after the Loc-RIB has been modified. It is
      responsible for disseminating routes in the Loc-RIB to each
      external peer, according to the policies contained in the PIB.

//    ^^^^^^^^^^^^^->Adj-RIB-Out?

      Route aggregation and information reduction can optionally be
      performed within this phase.

9.1.1 Phase 1: Calculation of Degree of Preference

   The Phase 1 decision function shall be invoked whenever the local BGP
   speaker receives from a peer an UPDATE message that advertises a new
   route, a replacement route, or withdrawn routes.

   The Phase 1 decision function is a separate process which completes
   when it has no further work to do.

   The Phase 1 decision function shall lock an Adj-RIB-In prior to
   operating on any route contained within it, and shall unlock it after
   operating on all new or unfeasible routes contained within it.

   For the newly received or replacement feasible route, the local BGP
   speaker shall determine a degree of preference.  If the route is
   learned from an internal peer, the value of the LOCAL_PREF attribute
   shall be taken as the degree of preference.  If the route is learned
   from an external peer, then the degree of preference shall be
   computed based on preconfigured policy information and used as the
   LOCAL_PREF value in any IBGP readvertisement. The exact nature of
   this policy information and the computation involved is a local
   matter. For a route learned from an external peer, the local speaker
   shall then run the internal update process of 9.2.1 to select and
   advertise the most preferable route.

// Hmmm... Can we incorporate the internal update process
// into 9.1.2 instead of specifying it separately?

9.1.2.1 Breaking Ties (Phase 2)

   In its Adj-RIBs-In a BGP speaker may have several routes to the same
   destination that have the same degree of preference. The local

Expiration Date October 2000                                   [Page 39]

RFC DRAFT                                                     April 2000

   speaker can select only one of these routes for inclusion in the
   associated Loc-RIB. 

// Add "(unless the speaker has been configured to support multiple
// best paths; this behavior is outside the scope of this document.)"

        The local speaker considers all routes with the
   same degrees of preference, both those received from internal peers,
   and those received from external peers.

   The following tie-breaking procedure assumes that for each candidate
   route all the BGP speakers within an autonomous system can ascertain
   the cost of a path (interior distance) to the address depicted by the
   NEXT_HOP attribute of the route.

// Add: "and follow the same algorithm"

   The tie-breaking algorithm begins by considering all equally
   preferable routes and then selects routes to be removed from
//                  ^ add "to the same destination"

   consideration.  The algorithm terminates as soon as only one route
   remains in consideration.  The criteria must be applied in the order
   specified.

   Several of the criteria are described using pseudo-code.  Note that
   the pseudo-code shown was chosen for clarity, not efficiency.  It is
   not intended to specify any particular implementation.  BGP
   implementations MAY use any algorithm which produces the same results
   as those described here.

      a) Remove from consideration routes with less-preferred
      MULTI_EXIT_DISC attributes.  MULTI_EXIT_DISC is only comparable
      between routes learned from the same neighboring AS.  Routes which
      do not have the MULTI_EXIT_DISC attribute are considered to have
      the highest possible MULTI_EXIT_DISC value.

      This is also described in the following procedure:

            for m = all routes still under consideration
                for n = all routes still under consideration
                    if (neighborAS(m) == neighborAS(n)) and (MED(n) < MED(m))
                        remove route m from consideration

      In the pseudo-code above, MED(n) is a function which returns the
      value of route n's MULTI_EXIT_DISC attribute.  If route n has no
      MULTI_EXIT_DISC attribute, the function returns the highest
      possible MULTI_EXIT_DISC value, i.e. 2^32-1.

      Similarly, neighborAS(n) is a function which returns the neighbor
      AS from which the route was received.

      b) Remove from consideration any routes with less-preferred
      interior cost.  The interior cost of a route is determined by
      calculating the metric to the next hop for the route using the
      interior routing protocol(s).  If the next hop for a route is
      reachable, but no cost can be determined, then this step should be

Expiration Date October 2000                                   [Page 40]

RFC DRAFT                                                     April 2000

      should be skipped (equivalently, consider all routes to have equal
      costs).

      This is also described in the following procedure.

            for m = all routes still under consideration
                for n = all routes in still under consideration
                    if (cost(n) is better than cost(m))
                        remove m from consideration

      In the pseudo-code above, cost(n) is a function which returns the
      cost of the path (interior distance) to the address given in the
      NEXT_HOP attribute of the route.

      c) If at least one of the candidate routes was received from an
      external peer in a neighboring autonomous system, remove from
      consideration all routes which were received from internal peers.

      d) Remove from consideration all routes other than the route that
      was advertised by the BGP speaker whose BGP Identifier has the
      lowest value.

9.1.3   Phase 3: Route Dissemination

   The Phase 3 decision function shall be invoked on completion of Phase
   2, or when any of the following events occur:

      a) when routes in a Loc-RIB to local destinations have changed

//                      ^->"the"     ^^^^^^^^^^^^^^^^^^ not clear what 
// "local destinations" means 

      b) when locally generated routes learned by means outside of BGP
      have changed

      c) when a new BGP speaker - BGP speaker connection has been
      established

   The Phase 3 function is a separate process which completes when it
   has no further work to do. The Phase 3 Routing Decision function
   shall be blocked from running while the Phase 2 decision function is
   in process.

   All routes in the Loc-RIB shall be processed into a corresponding
   entry in the associated Adj-RIBs-Out. Route aggregation and
   information reduction techniques (see 9.2.4.1) may optionally be
   applied.

   For the benefit of future support of inter-AS multicast capabilities,

Expiration Date October 2000                                   [Page 41]

RFC DRAFT                                                     April 2000

   a BGP speaker that participates in inter-AS multicast routing shall
   advertise a route it receives from one of its external peers and if
   it installs it in its Loc-RIB, it shall advertise it back to the peer
   from which the route was received. For a BGP speaker that does not
   participate in inter-AS multicast routing such an advertisement is
   optional. When doing such an advertisement, the NEXT_HOP attribute
   should be set to the address of the peer. An implementation may also
   optimize such an advertisement by truncating information in the
   AS_PATH attribute to include only its own AS number and that of the
   peer that advertised the route (such truncation requires the ORIGIN
   attribute to be set to INCOMPLETE).  In addition an implementation is
   not required to pass optional or discretionary path attributes with
   such an advertisement.

   When the updating of the Adj-RIBs-Out and the Forwarding Information
   Base (FIB) is complete, the local BGP speaker shall run the external
   update process of 9.2.2.

9.1.4 Overlapping Routes

   A BGP speaker may transmit routes with overlapping Network Layer
   Reachability Information (NLRI) to another BGP speaker. NLRI overlap
   occurs when a set of destinations are identified in non-matching
   multiple routes. Since BGP encodes NLRI using IP prefixes, overlap
   will always exhibit subset relationships.  A route describing a
   smaller set of destinations (a longer prefix) is said to be more
   specific than a route describing a larger set of destinations (a
   shorted prefix); similarly, a route describing a larger set of
   destinations (a shorter prefix) is said to be less specific than a
   route describing a smaller set of destinations (a longer prefix).

   The precedence relationship effectively decomposes less specific
   routes into two parts:

      -  a set of destinations described only by the less specific
      route, and

      -  a set of destinations described by the overlap of the less
      specific and the more specific routes

   When overlapping routes are present in the same Adj-RIB-In, the more
   specific route shall take precedence, in order from more specific to
   least specific.

   The set of destinations described by the overlap represents a portion

Expiration Date October 2000                                   [Page 42]

RFC DRAFT                                                     April 2000

   of the less specific route that is feasible, but is not currently in
   use.  If a more specific route is later withdrawn, the set of
   destinations described by the overlap will still be reachable using
   the less specific route.

   If a BGP speaker receives overlapping routes, the Decision Process
   MUST consider both routes based on the configured acceptance policy.
   If both a less and a more specific route are accepted, then the
   Decision Process MUST either install both the less and the more
   specific routes or it MUST aggregate the two routes and install the
   aggregated route.

// Add "provided that both routes have the same value of the NEXT_HOP
// attribute.

   If a BGP speaker chooses to aggregate, then it MUST add
   ATOMIC_AGGREGATE attribute to the route. A route that carries
   ATOMIC_AGGREGATE attribute can not be de-aggregated. That is, the
   NLRI of this route can not be made more specific.  Forwarding along
   such a route does not guarantee that IP packets will actually
   traverse only ASs listed in the AS_PATH attribute of the route.

9.2 Update-Send Process

   The Update-Send process is responsible for advertising UPDATE
   messages to all peers. For example, it distributes the routes chosen
   by the Decision Process to other BGP speakers which may be located in
   either the same autonomous system or a neighboring autonomous system.
   Rules for information exchange between BGP speakers located in
   different autonomous systems are given in 9.2.2; rules for
   information exchange between BGP speakers located in the same
   autonomous system are given in 9.2.1.

   Distribution of routing information between a set of BGP speakers,
   all of which are located in the same autonomous system, is referred
   to as internal distribution.

9.2.1 Internal Updates

   The Internal update process is concerned with the distribution of
   routing information to internal peers.

   When a BGP speaker receives an UPDATE message from an internal peer,
   the receiving BGP speaker shall not re-distribute the routing
   information contained in that UPDATE message to other internal peers.

// Add "unless the BGP speaker is configured to perform the route-reflector
// functionality, described in [RFC2796]"

   When a BGP speaker receives a new route from an external peer, it

Expiration Date October 2000                                   [Page 43]

RFC DRAFT                                                     April 2000

   MUST advertise that route to all other internal peers by means of an
   UPDATE message if this route will be installed in its Loc-RIB
   according to the route selection rules in 9.1.2.

   When a BGP speaker receives an UPDATE message with a non-empty
   WITHDRAWN ROUTES field, it shall remove from its Adj-RIB-In all
   routes whose destinations was carried in this field (as IP prefixes).

//                           ^^^->"were" 

   The speaker shall take the following additional steps:

      1) if the corresponding feasible route had not been previously
      advertised, then no further action is necessary

      2) if the corresponding feasible route had been previously
      advertised, then:

         i) if a new route is selected for advertisement that has the
         same Network Layer Reachability Information as the unfeasible
         routes, then the local BGP speaker shall advertise the
         replacement route

/* Change to:

         i) if a new route for the same NLRI is selected for advertisement,
            then the local BGP speaker shall advertise the replacement route

*/

         ii) if a replacement route is not available for advertisement,
         then the BGP speaker shall include the destinations  of the
         unfeasible route (in form of IP prefixes) in the WITHDRAWN
         ROUTES field of an UPDATE message, and shall send this message
         to each peer to whom it had previously advertised the
         corresponding feasible route.

   All feasible routes which are advertised shall be placed in the
   appropriate Adj-RIBs-Out, and all unfeasible routes which are
   advertised shall be removed from the Adj-RIBs-Out.

// "... after the corresponding update messages have been sent."

9.2.4.2 Aggregating Routing Information

   Aggregation is the process of combining the characteristics of
   several different routes in such a way that a single route can be
   advertised.  Aggregation can occur as part of the decision  process
   to reduce the amount of routing information that will be placed in
   the Adj-RIBs-Out.

   Aggregation reduces the amount of information that a BGP speaker must
   store and exchange with other BGP speakers. Routes can be aggregated
   by applying the following procedure separately to path attributes of
   like type and to the Network Layer Reachability Information.

   Routes that have the following attributes shall not be aggregated
   unless the corresponding attributes of each route are identical:
   MULTI_EXIT_DISC, NEXT_HOP.

// If the aggregation occurs as part of the update process, routes
// with different NEXT_HOP values can be aggregated when announced
// through an eBGP session.

   Path attributes that have different type codes can not be aggregated
   together. Path of the same type code may be aggregated, according to
   the following rules:

      ORIGIN attribute: If at least one route among routes that are
      aggregated has ORIGIN with the value INCOMPLETE, then the
      aggregated route must have the ORIGIN attribute with the value
      INCOMPLETE. Otherwise, if at least one route among routes that are
      aggregated has ORIGIN with the value EGP, then the aggregated
      route must have the origin attribute with the value EGP. In all
      other case the value of the ORIGIN attribute of the aggregated
      route is INTERNAL.

      AS_PATH attribute: If routes to be aggregated have identical
      AS_PATH attributes, then the aggregated route has the same AS_PATH
      attribute as each individual route.

      For the purpose of aggregating AS_PATH attributes we model each AS
      within the AS_PATH attribute as a tuple <type, value>, where
      "type" identifies a type of the path segment the AS belongs to
      (e.g. AS_SEQUENCE, AS_SET), and "value" is the AS number.  If the
      routes to be aggregated have different AS_PATH attributes, then
      the aggregated AS_PATH attribute shall satisfy all of the
      following conditions:

         - all tuples of the type AS_SEQUENCE in the aggregated AS_PATH
         shall appear in all of the AS_PATH in the initial set of routes
         to be aggregated.

         - all tuples of the type AS_SET in the aggregated AS_PATH shall

Expiration Date October 2000                                   [Page 48]

RFC DRAFT                                                     April 2000

         appear in at least one of the AS_PATH in the initial set (they
         may appear as either AS_SET or AS_SEQUENCE types).

         - for any tuple X of the type AS_SEQUENCE in the aggregated
         AS_PATH which precedes tuple Y in the aggregated AS_PATH, X
         precedes Y in each AS_PATH in the initial set which contains Y,
         regardless of the type of Y.

         - No tuple with the same value shall appear more than once in
         the aggregated AS_PATH, regardless of the tuple's type.

      An implementation may choose any algorithm which conforms to these
      rules.  At a minimum a conformant implementation shall be able to
      perform the following algorithm that meets all of the above
      conditions:

         - determine the longest leading sequence of tuples (as defined
         above) common to all the AS_PATH attributes of the routes to be
         aggregated. Make this sequence the leading sequence of the
         aggregated AS_PATH attribute.

         - set the type of the rest of the tuples from the AS_PATH
         attributes of the routes to be aggregated to AS_SET, and append
         them to the aggregated AS_PATH attribute.

         - if the aggregated AS_PATH has more than one tuple with the
         same value (regardless of tuple's type), eliminate all, but one
         such tuple by deleting tuples of the type AS_SET from the
         aggregated AS_PATH attribute.

      Appendix 6, section 6.8 presents another algorithm that satisfies
      the conditions and  allows for more complex policy configurations.

      ATOMIC_AGGREGATE: If at least one of the routes to be aggregated
      has ATOMIC_AGGREGATE path attribute, then the aggregated route
      shall have this attribute as well.

      AGGREGATOR: All AGGREGATOR attributes of all routes to be
      aggregated should be ignored.

9.3   Route Selection Criteria

   Generally speaking, additional rules for comparing routes among
   several alternatives are outside the scope of this document.  There
   are two exceptions:

Expiration Date October 2000                                   [Page 49]

RFC DRAFT                                                     April 2000

      - If the local AS appears in the AS path of the new route being
      considered, then that new route cannot be viewed as better than

//              ^-add: "(provided that the speaker has been configured
//    to receive such routes)"

      any other route.  If such a route were ever used, a routing loop
      could result (see Section 6.3).

      - In order to achieve successful distributed operation, only
      routes with a likelihood of stability can be chosen.  Thus, an AS
      must avoid using unstable routes, and it must not make rapid
      spontaneous changes to its choice of route.  Quantifying the terms
      "unstable" and "rapid" in the previous sentence will require
      experience, but the principle is clear.

// Care must be taken to ensure that BGP speakers in the same AS do
// not make inconsistent decisions.

6.1 Multiple Networks Per Message

// Ed pointed out some issues here:

   The BGP protocol allows for multiple address prefixes with the same
   AS path and next-hop gateway to be specified in one message. Making

// The above shoule be "..the same path attributes (including announced
// AS_PATH and announced NEXT_HOP)..."

   use of this capability is highly recommended. With one address prefix
   per message there is a substantial increase in overhead in the
   receiver. Not only does the system overhead increase due to the
   reception of multiple messages, but the overhead of scanning the
   routing table for updates to BGP peers and other routing protocols
   (and sending the associated messages) is incurred multiple times as

Expiration Date October 2000                                   [Page 55]

RFC DRAFT                                                     April 2000

   well. One method of building messages containing many address
   prefixes per AS path and gateway from a routing table that is not

// ... per a path attribute set...

   organized per AS path is to build many messages as the routing table

// organized on a per attribute set basis...

   is scanned. As each address prefix is processed, a message for the
   associated AS path and gateway is allocated, if it does not exist,

// associated set of attributes

   and the new address prefix is added to it.  If such a message exists,
   the new address prefix is just appended to it. If the message lacks
   the space to hold the new address prefix, it is transmitted, a new
   message is allocated, and the new address prefix is inserted into the
   new message. When the entire routing table has been scanned, all
   allocated messages are sent and their resources released.  Maximum
   compression is achieved when all  the destinations covered by the
   address prefixes share a gateway and common path attributes, making

//                  share a common set of attributes.

   it possible to send many address prefixes in one 4096-byte message.

   When peering with a BGP implementation that does not compress
   multiple address prefixes into one message, it may be necessary to
   take steps to reduce the overhead from the flood of data received
   when a peer is acquired or a significant network topology change
   occurs. One method of doing this is to limit the rate of updates.

// MinRouteAdvertisementInterval should be mentioned here.

   This will eliminate the redundant scanning of the routing table to
   provide flash updates for BGP peers and other routing protocols. A
   disadvantage of this approach is that it increases the propagation
   latency of routing information.  By choosing a minimum flash update
   interval that is not much greater than the time it takes to process
   the multiple messages this latency should be minimized. A better
   method would be to read all received messages before sending updates.

===8<===========End of original message text===========

- -- 
Alex Zinin

------- End of Forwarded Message

From: "Shah, VJ" <[email-masked]>
To: "[email-masked]'" <[email-masked]>
Subject: draft-ietf-idr-bgp-ext-communities-00.txt
Date: Wed, 15 Aug 2001 11:49:21 -0400
Sender: [email-masked]

In draft-ietf-idr-bgp-ext-communities-00.txt,
it is not clear to me how we can distinguish between regular and extended
types of Extended communities.
Can someone please clarify how the high order octet of the Type field can be
used for this?

Thanks,
VJ Shah

From: "Tsillas, Jim" <[email-masked]>
To: "'David Ball'" <[email-masked]>, Bob Salmi <[email-masked]>
Cc: [email-masked]
Subject: RE: Dynamic Capabilities Draft
Date: Mon, 13 Aug 2001 08:54:09 -0400
Sender: [email-masked]

I would have preferred a way of negotiating
dynamic capability update per capability but the
capability negotiation message doesn't have a
reserved (must-be-zero) flags area. Could we
include this information in the dynamic-capability
capability? This would allow implementations to
support some dynamic updates but not necessarily
all and it would be clear to the peer which are
supported. So instead of making the dynamic-capability
capability length zero, we can have an encoding
of capability code and flag which indicates if
dynamic updates are supported.

We then have to define the actions for these
dynamic updates. Each draft should be revised to
state what the actions are. It's obvious for some.

-Jim.

-----Original Message-----
From: David Ball [mailto:[email-masked]]
Sent: Friday, August 10, 2001 5:49 AM
To: Bob Salmi
Cc: [email-masked]
Subject: Re: Dynamic Capabilities Draft

On Thu, Aug 09, 2001, Bob Salmi wrote:
> Enke/Srihari, 
> 
> With respect to the dynamic capabilities draft, consider the following
case.
> 
> ORF is negotiated across a peering seesion and a set of filters are
installed
> and used.  Dynamic negotiation then turns off the ORF capability.  What
should
> be done with the installed orf filters.  Should they be left installed  or
> removed  ?
> 
> For some capabilities, I think we need to specify what actions should be 
> taken when a previously used capability has been removed dynamically.

I think this is a more general point - Enke already mentioned in the IDR
meeting that there are some capabilities like AS-4bytes which it
makes no sense to change dynamically.  For others, as you point out,
there may be special actions which need to be taken to deal with a
change in capability (and especially with the withdrawal of a
capability).

I think that we need to decide where the responsibility lies for
defining how existing capabilities operate dynamically.  Should that be
included in this draft?  A separate draft?  New drafts for each existing
capability?

	David

-- 
David Ball
<[email-masked]>

Date: Fri, 10 Aug 2001 10:48:49 +0100
From: David Ball <[email-masked]>
To: Bob Salmi <[email-masked]>
Cc: [email-masked]
Subject: Re: Dynamic Capabilities Draft
Sender: [email-masked]

On Thu, Aug 09, 2001, Bob Salmi wrote:
> Enke/Srihari, 
> 
> With respect to the dynamic capabilities draft, consider the following case.
> 
> ORF is negotiated across a peering seesion and a set of filters are installed
> and used.  Dynamic negotiation then turns off the ORF capability.  What should
> be done with the installed orf filters.  Should they be left installed  or
> removed  ?
> 
> For some capabilities, I think we need to specify what actions should be 
> taken when a previously used capability has been removed dynamically.

I think this is a more general point - Enke already mentioned in the IDR
meeting that there are some capabilities like AS-4bytes which it
makes no sense to change dynamically.  For others, as you point out,
there may be special actions which need to be taken to deal with a
change in capability (and especially with the withdrawal of a
capability).

I think that we need to decide where the responsibility lies for
defining how existing capabilities operate dynamically.  Should that be
included in this draft?  A separate draft?  New drafts for each existing
capability?

	David

-- 
David Ball
<[email-masked]>

Date: Fri, 10 Aug 2001 10:27:22 +0200
From: Aravind N Huchappa <[email-masked]>
To: [email-masked]
Subject: Multiprotocol Capability Advertisement with AFI=1, SAFI=1
Sender: [email-masked]

Hello,

I could not get clear answers to following questions from the
drafts. Hence here they are:

If a BGP peer advertise multiprotocol capability with AFI=1 and
SAFI=1 (i.e., normal IPv4 address), what can it mean? Does it
mean the peer can advertise IPv4 address in a MP_REACH_NLRI
(and withdraw IPv4 address in a MP_UNREACH_NLRI)?

What should be the behavior of BGP if it receives such an
advertisement? Should it send back a NOTIFICATION and terminate
the session or accept it? If such advertisement is accepted,
should the BGP be capable of handling IPv4 addresses in
MP_REACH_NLRI and MP_UNREACH_NLRI?

In any case (with or without multiprotocol capability advertisement
for IPv4 address), I assume that BGP should be able to handle IPv4
addresses in a normal BGP UPDATE (i.e., addresses present in the
withdraw route and NLRI parts of the update pdu).

Thanks,
Aravind

To: Bob Salmi <[email-masked]>
Cc: [email-masked], [email-masked]
Subject: Re: Dynamic Capabilities Draft 
Date: Thu, 09 Aug 2001 15:51:32 -0700
From: Enke Chen <[email-masked]>
Sender: [email-masked]

Bob,

> From: Bob Salmi <[email-masked]>
> Message-Id: <[email-masked]>
> Subject: Dynamic Capabilities Draft
> To: [email-masked]
> Date: Thu, 9 Aug 2001 12:12:44 -0500 (CDT)
> X-Mailer: ELM [version 2.5 PL1]
> MIME-Version: 1.0
> Content-Type: text/plain; charset=us-ascii
> Content-Transfer-Encoding: 7bit
> Sender: [email-masked]
> Precedence: bulk
> 
> Enke/Srihari, 
> 
> With respect to the dynamic capabilities draft, consider the following case.
> 
> ORF is negotiated across a peering seesion and a set of filters are installed
> and used.  Dynamic negotiation then turns off the ORF capability.  What should
> be done with the installed orf filters.  Should they be left installed  or
> removed  ?

Removed (as the capability is no longer there).

> 
> For some capabilities, I think we need to specify what actions should be 
> taken when a previously used capability has been removed dynamically.

The general rule seems to be obvious - do whatever that is necessary to remove
the effect of the previous announcement of the capability by the peer.

-- Enke

Date: Thu, 09 Aug 2001 19:21:36 +0200
From: Aravind N Huchappa <[email-masked]>
To: [email-masked]
Subject: Multiprotocol Capability Advertisement with AFI=1, SFI=1
Sender: [email-masked]

Hello,

I could not get clear answers to following questions from the
drafts. Hence here they are:

If a BGP peer advertise multiprotocol capability with AFI=1 and
SAFI=1 (i.e., normal IPv4 address), what can it mean? Does it
mean the peer can advertise IPv4 address in a MP_REACH_NLRI
(and withdraw IPv4 address in a MP_UNREACH_NLRI)?

What should be the behavior of BGP if it receives such an
advertisement? Should it send back a NOTIFICATION and terminate
the session or accept it? If such advertisement is accepted,
should the BGP be capable of handling IPv4 addresses in
MP_REACH_NLRI and MP_UNREACH_NLRI?

In any case (with or without multiprotocol capability advertisement
for IPv4 address), I assume that BGP should be able to handle IPv4
addresses in a normal BGP UPDATE (i.e., addresses present in the
withdraw route and NLRI parts of the update pdu).

Thanks,
Aravind

From: Bob Salmi <[email-masked]>
Subject: Dynamic Capabilities Draft
To: [email-masked]
Date: Thu, 9 Aug 2001 12:12:44 -0500 (CDT)
Sender: [email-masked]

Enke/Srihari, 

With respect to the dynamic capabilities draft, consider the following case.

ORF is negotiated across a peering seesion and a set of filters are installed
and used.  Dynamic negotiation then turns off the ORF capability.  What should
be done with the installed orf filters.  Should they be left installed  or
removed  ?

For some capabilities, I think we need to specify what actions should be 
taken when a previously used capability has been removed dynamically.

Bob

To: [email-masked]
Cc: [email-masked]
Subject: agenda
Date: Fri, 03 Aug 2001 08:17:55 -0700
From: Yakov Rekhter <[email-masked]>
Sender: [email-masked]

Folks,

Here is the agenda for the upcoming WG meeting

1. Agenda bashing (5 mins)
2. Olivier Bonaventure draft-bonaventure-bgp-redistribution-00.txt (15 mins)
3. Enke Chen draft-chen-bgp-dynamic-cap-01.txt (15 mins)
4. Howard C. Berkowitz draft-ietf-bmwg-conterm-00.txt (15 mins)
5. Howard C. Berkowitz  draft-berkowitz-tblgrow-00.txt (15 mins)
6. Bill Nickless draft-nickless-safi-mcast-app-01.txt (15 mins)
7. Jeff Haas draft-ietf-idr-bgp4-mib-07.txt (10 mins)
8. jeff Haas draft-ietf-idr-bgp4-mibv2-00.txt (15 mins)

Yakov.

From: "Barton F Bruce" <[email-masked]>
To: <[email-masked]>, <[email-masked]>, <[email-masked]>
Subject: Re: MPLS VPN conference scam?
Date: Thu, 2 Aug 2001 00:32:40 -0400
Sender: [email-masked]

I don't know about THAT particular conference, but Marcus Evans has several
offices globally, and runs all sorts of conferences and meetings and handles
the VIP stuff at the SuperBowl.

Some of their events are totally free and those invited will all be Cxx
titles and there will be maybe 60 to 120 of you from a very focused list.
You only pay your air fare to the resort. You do have an obligation to do
about 10 30 minute one-on-ones with vendor reps (mostly Cxx or SVP types,
not just sales-droids - they target inter-company relationships more than
just a sale). Intense and always very very worth while. Every minute is
scheduled for almost 2 solid days. The one-on-ones are a small piece, but
what pays for it all. The rest is seminars, round-tables, and social hour
networking.

Other typical Marcus Evans events are for $s but are always very
professionally run, and you will get what they say you will get.

They run these for an impressively large list of different industries. Their
staff work very hard.

If you get calls from several of them, complain. Some of the events that
were handled out of one of their CA offices are now done out on NYC. They
may have gotten some of their lists crossed. I get all calls from one person
now as he covers all the CLEC/ISP (IP/Fiber/Broadband etc) meeting I go to.

----- Original Message -----
From: <[email-masked]>
To: <[email-masked]>; <[email-masked]>
Sent: Wednesday, August 01, 2001 9:50 AM
Subject: MPLS VPN conference scam?

> For the past few days I've been getting calls from people claiming to be
from a company "Markus Evans". They try to sign you up for some BGP/MPLS VPN
"roundtable conference".
>
> When you ask for a web page with details they say they don't have one.
>
> When you ask them to put you on the "don't call list" they claim they
don't use call lists.
>
> When you ask to speak to a supervisor they refuse.
>
> Is this some scam? Does anyone who's behind this (I can't find any
information about this company "Markus Evans").
>
> R.
>
>
> __________________________________________________________________
> Your favorite stores, helpful shopping tools and great gift ideas.
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>
>

Date: Wed, 01 Aug 2001 09:50:43 -0400
From: [email-masked]
To: [email-masked], [email-masked]
Subject: MPLS VPN conference scam?
Sender: [email-masked]

For the past few days I've been getting calls from people claiming to be from a company "Markus Evans". They try to sign you up for some BGP/MPLS VPN "roundtable conference".

When you ask for a web page with details they say they don't have one.

When you ask them to put you on the "don't call list" they claim they don't use call lists.

When you ask to speak to a supervisor they refuse.

Is this some scam? Does anyone who's behind this (I can't find any information about this company "Markus Evans").

R.

__________________________________________________________________
Your favorite stores, helpful shopping tools and great gift ideas. Experience the convenience of buying online with Shop@Netscape! http://shopnow.netscape.com/

Get your own FREE, personal Netscape Mail account today at http://webmail.netscape.com/