> If you are probing to determine the initial PMTU, the answer is to send > periodic additional probes, of course. Routes are going to flap, and paths > are going to change - a once-probed MTU cannot be expected to remain > stable for any set length of time.
Did you really mean that? Clearly there has to be some assumption about the frequency at which the MTU can decrease. If not, for every e.g. TCP packet you send you would need to send an MTU probe (with an ACK) to make sure that a (TCP) packet of that size can make it to the neighbor. And since this is the L2 MTU and there will be multiple L2 instances along the L3 path one would either need to do such probing end2end (doubling the number of packets on the Internet), or have routers on the path perform hop-by-hop MTU probing including from the last hop router towards the destination host. Erik -------------------------------------------------------------------- IETF IPv6 working group mailing list [EMAIL PROTECTED] Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------