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Re: [NANOG] Microsoft.com PMTUD black hole?
On 5/7/08, Tomas L. Byrnes <tomb@xxxxxxxxxxx> wrote: > I'm not sure what the issue is here. > > Just about every modern firewall I've used has an option to enable PMTU > on interfaces, while blocking all other ICMP. > > Is MS not running something manufactured in the last 10 years at their > perimeter? Unless things have changed drastically since we parted ways, it's a simple ACL applied on all edge interfaces. It should be possible for them to modify it to allow the list of ICMP subtypes listed at http://www.cymru.com/Documents/icmp-messages.html It would *certainly* make troubleshooting easier for the poor folks at Microsoft, since one side effect of the edge filter being set that way meant we couldn't traceroute outside the network; the port unreachable messages never made it back, so everything outside the edge routers was all just stars. Of course, that was in a former lifetime, so it's entirely possible and probable things have changed considerably since then. ^_^;; Matt (speaking only for myself, not for my current employer, and most certainly not for my previous employer who I'm still somewhat bitter at, not having gotten any of my hardware back yet...) _______________________________________________ NANOG mailing list NANOG@xxxxxxxxx http://mailman.nanog.org/mailman/listinfo/nanog