[j-nsp] MTU changes affecting BGP sessions
raniery at rnp.br
Wed Jul 26 10:14:43 EDT 2006
I´d like to know if someone has seen the following issue.
I´ve got a M320 (Junos 7.5R2.8) with a few BGP peerings. These peerings
run on vlans over a L2 infrastructure built on Ethernet switches (Cisco
and Foundry). Some of these switches are configured to support jumbo
frames, around 9000 bytes, some are not yet.
Then I changed physical MTU in the M320 GigE interface to 9000 bytes.
Most peerings just flapped and came up fine, but one started to flap
continuously. This one stays up for about 90seg (bgp holdtime?) and goes
I´ve tried "mtu-discovery" bgp command on my side, but didn´t help. No
clue about the other side, so far.
Did anyone see this kind of thing? Hints about a solution?
Another interesting fact : there is another BGP peer (multihop 2) in
this same problematic vlan, and it works fine after mtu change. But I´m
almost sure it´s a Juniper, so no interop issues ;)
Jul 26 10:57:30 jm320_sp rpd: bgp_event: peer xxx (External AS
xxx) old state OpenConfirm event RecvKeepAlive new state Established
Jul 26 10:59:00 jm320_sp rpd: bgp_traffic_timeout: NOTIFICATION
sent to xxx (External AS xxx): code 4 (Hold Timer Expired Error),
Reason: holdtime expired for xxx (External AS xxx), socket buffer sndcc:
0 rcvcc: 0 TCP state: 4, snd_una: 3621665251 snd_nxt: 3621665251
snd_wnd: 16200 rcv_nxt: 3247700880 rcv_adv: 3247759208, keepalive timer 0
Jul 26 10:59:00 jm320_sp rpd: bgp_event: peer xxx (External AS
xxx) old state Established event HoldTime new state Idle
More information about the juniper-nsp