From: Yves@xxxxxxxxx
Date: Tue Jan 01 2002 - 11:26:41 GMT-3
Hi Paul,
here's what I know (I did not have the possibility to double-check, but
I'm quite sure about it)
For Cisco --- Cisco peering :
- The peer that initiates the dlsw peering uses a radom source port (like
1023) and the destination port 2065 for its tcp session, it also listens
on port 2065 and 2067.
- The other peer then initiates a tcp session back using the same
destination port (2065) for the session.
- Now there are two tcp sessions open between the peers, one in each
direction.
- After Cap-Exchange the peer with the !! higher IP address !! tears down
the session that it initiated. Only one bi-drectional session is left
open.
For Cisco --- IBM, or IBM --- IBM (original DLSW v2 spec) peering :
- The peer that initiates the dlsw peering uses a random source port (like
1023) and uses the destination port 2065 for its tcp session, it also
listens on port 2067 (and 2065 for Cisco).
- The other peer then initiates a tcp session back using the destination
port 2067
- Now there are two tcp sessions between the peers, one using destination
port 2065 and another session back using destination port 2067.
- After Cap exchange both sessions are kept. Two uni-directional sessions
are open
References :
great IBM redbook about cisco - IBM interoperability :
http://publib-b.boulder.ibm.com/Redbooks.nsf/9445fa5b416f6e32852569ae006bb65f/d
214bd2179ecc24d852568570050821a?OpenDocument&Highlight=0,SG24-5865-00
well known cisco TAC link
http://www.cisco.com/warp/public/697/6.html
have fun,
Yves
Paul Young <tsungdapaulyoung@yahoo.com>
Sent by: nobody@groupstudy.com
01.01.2002 00:15
Please respond to Paul Young
To: ccielab@groupstudy.com
cc:
Subject: DLSW tcp ports/peering process
Hi Group:
Below is my understanding of how DLSW peering
works, please comment or point out reference if
possible, thanks.
R1 (higher peer id) ---- R2 (lower peer id)
R1 uses tcp port 2065 -> R2 (tcp port >1023) and
listens on tcp port 2067
R1 (port > 1023) <- R2 (tcp port 2065)
Because R2 has lower peer id, it's torn down
R1 receives on port 2067 from R2 and peering
establishes.
If priority is used 1981, 1982, 1983, 1984 are also used.
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