One other alternative is that "no icmp unreachables" is enabled...
http://packetlife.net/blog/2008/oct/9/disabling-unreachables-breaks-pmtud/ -- Andrew On Wed, Jul 22, 2015 at 5:30 PM, Painting, Stuart <stuart.paint...@theaa.com> wrote: > Two obvious scenarios: > > 1. ICMP type 3 packets are being blocked (e.g. by an overenthusiastic > firewall). > 2. ICMP packets are never generated. Consider a situation where MTU mismatch > exists at layer 2 (e.g. a Cat6500 cross-connected to an older Cat4500 that > can't do jumbo frames). The sending end (MTU 9100) will transmit the packet, > but the receiving end (MTU 1500) will silently discard the incoming "giant". > > > -----Original Message----- > From: cisco-nsp [mailto:cisco-nsp-boun...@puck.nether.net] On Behalf Of Adam > Vitkovsky > Sent: 21 July 2015 23:44 > To: Mark Tinka; CiscoNSP List; James Bensley; cisco-nsp@puck.nether.net > Subject: Re: [c-nsp] MTU / BGP > > And this is what bothers me, maybe I'm too tired, but I can't think of a > reason why Path MTU Discovery would not work properly (even with asynchronous > MTU settings). > > adam > > > > _______________________________________________ > cisco-nsp mailing list cisco-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ > cisco-nsp mailing list cisco-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
