BGP & MTU

[Jared Mauch <jared () puck nether net>]

> On Jul 22, 2016, at 1:37 PM, Grzegorz Janoszka <Grzegorz () Janoszka pl> wrote:
>
> On 2016-07-22 15:57, William Herrin wrote:
> > On a link containing only routers, you can safely increase the MTU to
> > any mutually agreed value with these caveats:
>
> What I noticed a few years ago was that BGP convergence time was faster with higher MTU.
> Full BGP table load took twice less time on MTU 9192 than on 1500.
> Of course BGP has to be allowed to use higher MTU.
>
> Anyone else observed something similar?

This has been well known for years:

http://morse.colorado.edu/~epperson/courses/routing-protocols/handouts/bgp_scalability_IETF.ppt

You have to adjust the MTU, Input queues and such.  The default TCP stack is very conservative.

- Jared