Le 8 févr. 2010 à 22:08, Templin, Fred L a écrit : > Also, there seems to be some evidence that ICMPv6 PTB > messages are being dropped in the network.
In IPv6, I hope it will be possible to agree at least that PTB messages SHOULD be forwarded (if not MUST). Reasons to not agree should IMHO be seriously documented. > ... for DF=1 packets the tunnel > ingress MUST send an ICMP PTB when the packet is larger > than a fixed minimum tunnel MTU and also too large to > traverse the tunnel in a single piece. For packets that > are no larger than the fixed minimum tunnel MTU, the > tunnel ingress SHOULD use tunnel fragmentation (i.e., > SEAL segmentation and reassembly). Presumably, the tunnel > ingress would choose a fixed minimum tunnel MTU that is > large enough so that source hosts will not see excessive > data loss and retransmissions due to path MTU discovery > interactions. > > For many/most deployments, a fixed minimum tunnel MTU of > 1500 bytes would seem advisable. In my understanding, we can keep the current IPv6 value of 1280 as the minimum that has to traverse ALL tunnels, and note that if a tunnel has an internal mechanism to fragment at entrance and reassemble at exit (e.g. SEAL), the tunnel advertised MTU can become independent from that of the traversed infrastructure. Thoughts? Cheers, RD _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
