The documentation says that Path MTU discovery is enabled by default for all BGP neighbor sessions:
http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/irp_bgp_neighor.html#wp1054165 So enabling "ip tcp path-mtu-discovery" should not be necessary. But i made some tests with 12.0S and it seems the documentation is not accurate: - In the same 1500 bytes MTU ethernet segment, without that command the SYN packet is sent with MSS=536 bytes. - With that command, the SYN packet is sent with MSS=1460 bytes. This seems buggy to me :( Regards, Antonio Soares, CCIE #18473 (R&S) [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Lukasz Bromirski Sent: quarta-feira, 11 de Fevereiro de 2009 23:40 To: Jose Conceicao Cc: cisco-nsp Subject: Re: [c-nsp] BGP MSS=576 bytes On 2009-02-11 21:51, Jose Conceicao wrote: > After choosing whatever prefered method, wouldn't these BGP sessions > need to be re-established to take effect? (since MSS is only carried > in SYN and SYN/ACKs) Sure. > And shouldn't u account for TCP/IP overhead? (just being lazy by not > testing this in lab) TCP/IP overhead of what actually? Here's a whitepaper on PMTUD/MSS: http://www.cisco.com/en/US/tech/tk827/tk369/technologies_white_paper09186a00800d6979.shtml And there's CSCef52888 for all of You pre 12.2(18)SXF12 guys which doesn't actually have PMTUD do it's work. -- "Don't expect me to cry for all the | Łukasz Bromirski reasons you had to die" -- Kurt Cobain | http://lukasz.bromirski.net _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
