At 12:34 AM 6/16/2004, Sally Floyd wrote... >Alberto Medina, Mark Allman, and I have a draft paper on >"Measuring the Evolution of Transport Protocols in the Internet" >that has a section (Section V.B.) on Path MTU Discovery. >>From the paper: > >"Table X shows that PMTUD is used and succeeded for slightly less >than half of the [web] servers on our list. For 31\% of the servers >on our list, the server did not attempt Path MTU Discovery. For >18\% of the servers on our list, Path MTU Discovery failed, presumably >because of middleboxes that block ICMP packets on the path to the >web server." Any router configured to block ICMP packets is, quite simply, in violation of RFC792 (STD5), which clearly states "ICMP is actually an integral part of IP, and must be implemented by every IP module." For a router, "implemented" means forwarded to the destinations next hop. So the fact is, by blocking ICMP, such ISPs have broken IP connectivity, and can no longer claim to be providing Internet (IP) service. _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf