On 7/22/16, Phil Rosenthal <p...@isprime.com> wrote: > >> On Jul 22, 2016, at 1:37 PM, Grzegorz Janoszka <grzeg...@janoszka.pl> >> wrote: >> 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? > > I have read about others experiencing this, and did some testing a few > months back -- my experience was that for low latency links, there was a > measurable but not huge difference. For high latency links, with Juniper > anyway, there was a very negligible difference, because the TCP Window size > is hard-coded at something small (16384?), so that ends up being the limit > more than the tcp slow-start issues that MTU helps with.
I think the Cisco default window size is 16KB but you can change it with ip tcp window-size NNN Lee > > With that said, we run MTU at >9000 on all of our transit links, and all of > our internal links, with no problems. Make sure to do testing to send pings > with do-not-fragment at the maximum size configured, and without > do-not-fragment just slightly larger than the maximum size configured, to > make sure that there are no mismatches on configuration due to vendor > differences. > > Best Regards, > -Phil Rosenthal