On Mon, Aug 31, 2015 at 3:49 PM, <sthaug@nethelp.no> wrote:
ICMP replies to multicast packets can cause ICMP "implosion". This is not a new discussion - see for instance
http://mailman.nanog.org/pipermail/nanog/2012-June/048685.html
It's a shame we handle path MTU as a layer 3 problem that gets an ICMP response from a middlebox. It'd make more sense to truncate the packet, set a flag, and then let layer 4 at the recipient deal with negotiating a new size with the sender. You know, end to end principle and all. That'd eliminate the problems with firewall-blocked protocols and routers using private IP addresses, the usual culprits for pmtud breakage. It'd also let multicast protocols make reasonable choices for that particular protocol without being stuck with the stack's default. -Bill -- William Herrin ................ herrin@dirtside.com bill@herrin.us Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>