On Thu, Nov 27, 2008 at 8:10 AM, Dino Farinacci <[EMAIL PROTECTED]> wrote: > I am just wondering how many people have ICMP Destination Unreachables > disabled on their core routers. Could an CPE router, which may encapsulate > data, be able to depend on ICMP Unreachables to be sent to it? > > I know there are many cases where router implementations default it to off > (to not send ICMP DUs), but wondering who leaves it this way or turns them > on? Of when it defaults to on, who explicitly turns them off.
Most of people who disable ICMP DU just don't understand what ICMP DU is for. Need I mention that PMTUD relies on ICMP type 3/code 4... In addition, it looks like that "no ip unreach" interface command disables "too big" message as well, breaking PMTUD. I prefer to enable ICMP DU on any interfaces where fragmentation may occur. P.S. Fortunately, there are separate types for "Packet Too Big" and "Destination Unreachable" messages in ICMPv6 ;-) -- SY, Jen Linkova aka Furry _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
