On 01/05/2012 10:08 PM, Templin, Fred L wrote: >> On 01/04/2012 11:55 PM, Brian E Carpenter wrote: >> The problem with RFC4821 (assumming the ICMP-free variant) is that it >> has a longer convergnece time that ICMP-enabled PMTU. > > RFC4821 works even if there are no ICMPs, but will > converge more quickly if there are ICMPs. That is why > RFC4821 should be a SHOULD for hosts, and generation > of ICMPs should be a MUST for routers.
Agreed. >> That's why people think of RFC4821 as a mechanism for PMTUD blackhole >> detection rathern than as a repalcement for traditional PMTUD >> (i.e., you >> use the transport-layer probes when it looks like >> tradictional PMTUD is >> not working (possibly as a result of filtered ICMP error messages)). > > The two are complementary. It was originally meant to be a replacement for traditional PMTUD. Then it was relaxed and RFC4821 allowed for it to be used only in the presence of PMTUD blackholes. Thanks, -- Fernando Gont SI6 Networks e-mail: [email protected] PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492 -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
