[j-nsp] BGP Hold-times

[Arda Balkanay]

The minimum configurable hold-time in junos seems to be 6 (range between 6
and 65535 and it can depend on the junos version. My tests were with
7.4R4.3) if you try to set a lower value you will get "value 3 is not within
range (6..65535) at '3' "

Also the message is "%DAEMON-4" which is syslog level 4 message. In other
words it is a warning not an error.

We use this kind of setup with a hold time of 6 in our backbone and it works
fine.

Regards
Arda Balkanay


-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Jee Kay
Sent: 28 Aralık 2006 Perşembe 16:58
To: juniper-nsp at puck.nether.net
Subject: [j-nsp] BGP Hold-times

Hi all,

We're running BGP in an HA environment, using a hold-time of 3
seconds. This translates to a KA interval of 1s and is working for us
on all of our Ciscos.

The lowest hold-time you can confirm on the Junipers seems to be 9
seconds.. however as per the BGP spec if two devices disagree on the
timer then the lowest should be used. To me, this means that 3 seconds
should end up being used.

However, when the peering comes up the Juniper logs the following:

rpd[2701]: %DAEMON-4: bgp_get_open: peer x.y.28.229 (Internal AS z):
hold time too small (3), set to minimum (20)


But... a show neighbor shows the below:

Juniper> show bgp neighbor x.y.28.229
Peer: x.y.28.229+11038 AS z Local: x.y.129.218+179 AS z
  Holdtime: 9 Preference: 170


At this point I am confused.. the Cisco thinks the hold-time is 3
seconds. The Juniper seems to have disagreed and set it to 20 second
but the show neighbor says 9 seconds.

Has anyone seen this before? Is it possible to get the Junipers down
to a hold-time of 3?

Failing this, how are people handling sub-10s convergence when running BGP?

Thanks,
Ras
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