Subject: Re: [L2tpext] IP Layer 2 Transport over L2TPv3

From: Prasad Yadati <[email-masked]>
Date: Sat, 17 Sep 2005 10:50:03 +0100

Good one Carlos.
How about just specifying it as "IP transport over L2TPv3".

Wondering whether we can have a generic "Layer 3 transport over L2TPv3" and 
specify transport of all layer 3 protocols (IP, IPX,....) in it including IP.

Regards
Prasad

Carlos Pignataro wrote:
> Hi All,
> 
> We submitted the following `IP Layer 2 Transport over L2TPv3' draft:
> http://www1.ietf.org/mail-archive/web/i-d-announce/current/msg06623.html
> that details the tunneling of IP datagrams directly over an L2TPv3
> session, and defines the `CE IP Address AVP' as well.
> 
> We would like it to become an l2tpext working group document, and seek
> review, feedback and comments from the WG.
> So we ask here for the draft to be accepted as work item for the group.
> Your feedback will be most appreciated.
> 
> Thanks,
> 

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From: James Carlson <[email-masked]>
Date: Mon, 19 Sep 2005 08:48:14 -0400

> specify transport of all layer 3 protocols (IP, IPX,....) in it including IP.

If it's no longer carrying L2 traffic, should L2TP perhaps be renamed?

-- 
James Carlson, KISS Network                    <[email-masked]>
Sun Microsystems / 1 Network Drive         71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677

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From: Carlos Pignataro <[email-masked]>
Date: Mon, 19 Sep 2005 22:52:28 -0400

Prasad,

Thanks. Please see a couple of comments inline.

List,

Any further comments on the request to accept this draft as a working
group document?

> How about just specifying it as "IP transport over L2TPv3".

Thanks.

The "IP Layer 2" was added there for 2 reasons:
1. To somehow differentiate raw-IP from framed-IP being transported over
   L2TPv3 while trying to reference the NSP function that interfaces the
   L2 AC with the IP PW Termination.
2. Symmetry/parity name with the already defined PW Type for MPLS PWE3.

"IP transport" may possibly be too generic for the procedures defined.

> Wondering whether we can have a generic "Layer 3 transport over L2TPv3"
> and specify transport of all layer 3 protocols (IP, IPX,....) in it
> including IP.

Do you mean multiple L3 protocols at the same time over the session? I'd
think we can use existing L2 transports to accomplish that. OTOH, IP as
L3 stands out in the applications of an "IP L2" session.

Thanks !

--Carlos.

-- 
--Carlos.
Escalation RTP - cisco Systems

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From: Ignacio Goyret <[email-masked]>
Date: Mon, 19 Sep 2005 20:03:13 -0700

>If it's no longer carrying L2 traffic, should L2TP perhaps be renamed?

I've been asking myself that same question ever since L2TPv3 evolved from
the simple quick update to L2TPv2 that I was told it was going to be to
the monster that it has become.

In hallway conversations, I've started using the term "LxTP" to distinguish
the two -- a term that I'll readily agree is not as sexy as "L2TP" but it
seems to better reflect the extended capabilities of the new protocol
defined in RFC3931.

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From: Prasad Yadati <[email-masked]>
Date: Tue, 20 Sep 2005 12:01:45 +0100

Carlos,

Please see in-line.

> 2. Symmetry/parity name with the already defined PW Type for MPLS PWE3.

But as per this draft, no "IP layer 2" information is transported. Rather we are 
trying to prevent the same. For me, "IP layer 2" seems to be mis-leading.

> "IP transport" may possibly be too generic for the procedures defined.

Corlos, for me, "IP transport" seems more appropriate than current. In this case 
as far as L2TPv3 is concerned, it is transporting IP rather than layer 2 frame.

> L3 stands out in the applications of an "IP L2" session.
Sorry I was not clear. I meant to combine specification of other layer 3 data 
packets over L2TPv3 in one draft. May be that is not needed. We may have separate 
similar such of these drafts for other layer 3 protocols. Please ignore this comment.

Thanks
Prasad

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From: Carlos Pignataro <[email-masked]>
Date: Thu, 22 Sep 2005 21:27:04 -0400

Hi Prasad,

Please see inline.

Circa 9/20/2005 7:01 AM, Prasad Yadati said the following:
> But as per this draft, no "IP layer 2" information is transported.

Yes, only IP datagrams are transported, although there is a Layer 2
attachment circuit, and hence "IP Layer 2". The NSP function "extracts
IP datagrams from the Layer 2 frames" and that's the motivation for the
name, make a distinction from framed-IP. See below as well.

> Rather we are trying to prevent the same. For me, "IP layer 2" seems to
> be mis-leading.
> 
> 
> Corlos, for me, "IP transport" seems more appropriate than current. In
> this case as far as L2TPv3 is concerned, it is transporting IP rather
> than layer 2 frame.

IMHO, "IP transport" is too generic, and does not fully convey what's
happening in the interface between the physical layer 2 interface and
the pseudowire termination. Other PW Types transport IP (framed-IP) as
well. I thought about "raw ip" and "native ip" but opted against them
for a similar reason. Any other suggestions?

> Sorry I was not clear. I meant to combine specification of other layer 3
> data packets over L2TPv3 in one draft. May be that is not needed. We may
> have separate similar such of these drafts for other layer 3 protocols.
> Please ignore this comment.

OK. Thanks,

--Carlos.

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From: Prasad Yadati <[email-masked]>
Date: Fri, 23 Sep 2005 13:00:19 +0100

Hi Carlos,

Please see in-line.

> attachment circuit, and hence "IP Layer 2". The NSP function "extracts

Attachment circuit layer 2 is already terminated. Isn't it ? L2TPv3 in this case 
does not aware of attachment circuit's layer 2. In fact it does not matter what 
kind of layer 2 IP was carried at the attachment circuit.
I am sorry Corlos, I am still not clear.

> for a similar reason. Any other suggestions?

How about "Abstracted/Extracted IP over L2TPv3" ?
If this draft can be, really generic, I mean if it  can be used even for non-pw 
cases where L2TPv3 carries generic IP datagrams, we may have "IP transport over 
L2TPv3" ?

Kind Regards
Prasad

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From: Carlos Pignataro <[email-masked]>
Date: Tue, 27 Sep 2005 23:46:29 -0400

Hi Prasad,

Circa 9/23/2005 8:00 AM, Prasad Yadati said the following:
> Attachment circuit layer 2 is already terminated. Isn't it ? L2TPv3 in
> this case does not aware of attachment circuit's layer 2. In fact it
> does not matter what kind of layer 2 IP was carried at the attachment
> circuit.

Although the "IP Layer 2" was intended to make the NSP function
explicit, I understand (and agree on second thoughts) the argument that
can be confusing with what's actually being transported.

How about this to describe the main aspects of the draft:
"Signaling and Encapsulation for the Transport of IP over L2TPv3"

There are also two further items in the draft to possibly update:
1. "IP Layer 2 interface": I'd leave this one as is.
2. PW Type/PW name: If changing the title, I'd also update:
	IPL2PW IP Layer 2 Transport Pseudowires
	IP Layer 2 Transport Pseudowire Type.
   to:
	IPPW   IP Transport Pseudowires
	IP Transport Pseudowire Type.

Would this aid in clarity?

Thanks for your comments !

--Carlos.

> If this draft can be, really generic, I mean if it  can be used even for
> non-pw cases where L2TPv3 carries generic IP datagrams, we may have "IP
> transport over L2TPv3" ?
> 
> Kind Regards
> Prasad
> 
> 
> 
>>
>>
>>>>

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From: Prasad Yadati <[email-masked]>
Date: Thu, 29 Sep 2005 04:51:17 +0100

Hi Carlos,

> "Signaling and Encapsulation for the Transport of IP over L2TPv3"

Looks good to me, Carlos.

> 1. "IP Layer 2 interface": I'd leave this one as is.
Carlos, why not we just use AC (attachment circuit) instead, so that it will be 
consistent with rest of the L2TPv3 RFCs.

> 	IP Transport Pseudowire Type.

Looks good.

Thanks a lot for taking care of the comments Carlos.

Regards
Prasad

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From: Carlos Pignataro <[email-masked]>
Date: Thu, 29 Sep 2005 12:18:21 -0400

Circa 9/28/2005 11:51 PM, Prasad Yadati said the following:
> Carlos, why not we just use AC (attachment circuit) instead, so that it
> will be consistent with rest of the L2TPv3 RFCs.
> 

Yes, AC is already used.

> Thanks a lot for taking care of the comments Carlos.

Thank you for the comments.

Regards,

--Carlos.