BGP and convergence time

Richard A Steenbergen ras at
Thu May 13 01:45:42 UTC 2010

On Wed, May 12, 2010 at 09:52:48AM -0600, Danny McPherson wrote:
> The holdtime isn't technically negotiated, both sides convey their
> value in the open message and the lower of the two is used by both BGP
> speakers.  IIRC, neither J or C reset the session with the timer
> change, but the new holdtimer expiry value doesn't take effect until
> then.

Rest assured J will always reset the session if given given half a
chance, and changing your holdtime is more than half. :)

One thing I find interesting is that most other protocols will err on
the side of caution and use the higher of two values like this when
negotiating between two parties, but BGP does the opposite. I still run
into bad bgp implementations which can't keep up with my 30 sec hold
timers all the time *coughghettoequinixrouteservercough*.

Richard A Steenbergen <ras at>
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)

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