Subject: Notification message: "session rejected, no Hello"

From: Vrishab Sikand <[email-masked]>
Date: Thu, 23 Sep 1999 15:32:39 -0400

LDP-05 calls for passive LSR to send a notification message during
session initialization, when
no matching hello adjacency is found.

My Q is what LDP ID, will you put in the Header of this  notification
message?? you have established
no adjacency with this potential peer hence there is no valid Label
space ID to insert.

I suggest that the

--
tx
Vrishab Sikand

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From: Srinivasan Balaji <[email-masked]>
Date: Thu, 23 Sep 1999 15:47:49 -0400

Vrishab,
   I guess you wanted to say that the "Receiver LDP Identifier"
in the Initialization message should be the LDP ID in the Notification.

Right ?

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From: Vrishab Sikand <[email-masked]>
Date: Thu, 23 Sep 1999 16:11:49 -0400

This section in LDP-05 states that The Ldp identifier "Six octet field that
uniquely identifies the label space of the
     sending LSR for which this PDU applies."

Now think of the scenario i am describing, the passive LSR accepts a TCP
connection from the
peer, it has to wait for the Init message before it can know which Label
Space (or adjacency the peer is talking about)
on receiving the first Ldp Pdu on this connection it determines that it has
No Matching Hello adjacency.

Now it has to build and send a notification message with status = 10
(session rejected , no hello)
But since it has no adjacency with this peer, what would be the LDP
Identifier in this notification message

3.1. LDP PDUs

   Each LDP PDU is an LDP header followed by one or more LDP messages.
   The LDP header is:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Version                      |         PDU Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         LDP Identifier                        |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Version
     Two octet unsigned integer containing the version number of the
     protocol.  This version of the specification specifies LDP protocol
     version 1.

   PDU Length
     Two octet integer specifying the total length of this PDU in
     octets, excluding the Version and PDU Length fields.

     The maximum allowable PDU Length is negotiable when an LDP session
     is initialized.  Prior to completion of the negotiation the maximum
     allowable length is 4096 bytes.

   LDP Identifier

Andersson, et al.                                              [Page 29]

Internet Draft         draft-ietf-mpls-ldp-05.txt              June 1999

     Six octet field that uniquely identifies the label space of the
     sending LSR for which this PDU applies.  The first four octets
     encode an IP address assigned to the LSR.  This address should be
     the router-id, also used to identify the LSR in loop detection Path
     Vectors.  The last two octets identify a label space within the
     LSR.  For a platform-wide label space, these should both be zero.

--
tx
Vrishab Sikand

Quarry Technologies
8 New England Office Park
Burlington Ma 01803

Off : 781 505 8300 ext. 332
Fax : 781 505 8316
Res.: 781 395 7280

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From: Vasanthi Thirumalai <[email-masked]>
Date: Thu, 23 Sep 1999 23:35:56 -0400

Vrishab,
   Since the spec. is not so clear as to what LDP ID should
be sent in this case, what seems to be the safest in the
situation is to copy the "Receiver LDP ID" from the
Initialization message into the notification message.
    In any case the TCP connection would be torn
down following transmission of the notification
message by the passive LSR.

>    Each LDP PDU is an LDP header followed by one or more LDP messages.

Vasanthi Thirumalai
Lucent Technologies

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From: Vrishab Sikand <[email-masked]>
Date: Fri, 24 Sep 1999 10:54:24 -0400

i think that the passive LSR should not be required to send a notification
message
in this somewhat FUZZY state. It should just close the TCP connection.

--
tx
Vrishab Sikand

Quarry Technologies