> Date: Fri, 19 Sep 2008 09:45:33 -0700 (PDT) > From: "P.Narayana Swamy" <[EMAIL PROTECTED]> > Sender: [EMAIL PROTECTED] > > Hi, > The EBGP session failed between Juniper and other vendor with the > following log in Juniper Chassis. Juniper chassis sent the Hold timer > expired Notification and ceased the session. Could you please let me > know the reason for this Holdtime expiry? Were there any TCP session > failure or any Path MTU issues from the following log:
Looks a lot like an MTU mismatch. BGP does not do PMTU and sets do not fragment, so the MTUs need to be the same on both ends. Things like VLAN or tunneling can mess this up. You can try capturing the traffic to confirm this. I use tcpdump (in the shell as root) and move the output file to a box where I can run wireshark on it. You will see the big frame being re-transmitted several times. This is probably not really required, though. The common symptom is that one end (the one with the larger MTU) will get "stuck" with a message in the outbound queue that never gets sent. This is visible in "sho bgp sum | grep peer-ip-address". The fifth column is the one you will see freeze for a while and slowly grow as keep-alives are added to the queue. At that point, the keep-alives and other stuff is blocked in the output queue and never gets sent. Finally, the session times out and you start over. This is not -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: [EMAIL PROTECTED] Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
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