Subject: Multiple adjacencies per session.

From: Haseeb Budhani <[email-masked]>
Date: Mon, 14 May 2001 16:47:00 -0500

Hello folks,

I have a few simple questions pertaining to the existence of multiple
adjacencies per session, which RFC3036 says can only happen for
point-to-point links (2.5.5 : Maintianing Hello Adjacencies)

1. Does one "session" between two peers denote one TCP connection
between the two ??

2. If the answer to (1) is Yes, does this mean that for n adjacencies in
a session, only one -- the primary -- adjacency has an active
TCP connection, which it uses to exchange LDP specific information, and
the other n-1 adjacencies remain "idle" ?

3. If the answer to (1) is No, is there a TCP connection set up for
every adjacency, and is this TCP connection used to exchange
LDP specific data ??

Please get back to me at your earliest convenience.

Thank. :)

--
Haseeb Budhani.

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From: Bob Thomas <[email-masked]>
Date: Tue, 15 May 2001 06:54:37 -0400

Haseeb,

> point-to-point links (2.5.5 : Maintianing Hello Adjacencies)

RFC3036 does not say this can happen only for point-to-point links.
It cites the case of muliple PPP links between a pair of LSRs as an
example.

> 1. Does one "session" between two peers denote one TCP connection

Yes, one session means one TCP connection.

> the other n-1 adjacencies remain "idle" ?

I don't know what you mean by "idle".  The hello discovery adjacencies
associated with an LDP session are equivalent in their role of maintaining
the LDP session.

> every adjacency, and is this TCP connection used to exchange

The answer to (1) is yes; there is 1 TCP connection per session.

Bob

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From: Eric Gray <[email-masked]>
Date: Tue, 15 May 2001 09:37:29 -0400

Haseeb,

    To add to Bob's reply to your question #2 below, TCP connections
are not normally associated with a single link when multiple links
(adjacencies) exist between the IP entities that TCP connects.  TCP
connections are from IP entity to IP entity.  How TCP packets get from
one IP entity to the other, when there is more than one way, is largely a
local choice for the packet's sender.

--
Eric Gray