On 22 Jul 2016, at 19:37, 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.
Quite obvious thing - BGP by default on Cisco and Juniper will use up to max allowed 4k message per packet, which for typical unicast IPv4/v6 helps to pack all attributes with prefix. This not only improves (lowers) CPU load on sending side but also on the receiving end and helps with routing convergence. There was a draft to use up to 9k for BGP messaging, but I belive it's buried somewhere on the outside of town called "our current version RFC". -- Łukasz Bromirski