[c-nsp] MTU / BGP

[Andrew Miehs]

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.Painting at 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-bounces at puck.nether.net] On Behalf Of Adam Vitkovsky
> Sent: 21 July 2015 23:44
> To: Mark Tinka; CiscoNSP List; James Bensley; cisco-nsp at 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
>
>
>
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