Hi Joe, > -----Original Message----- > From: Joe Touch [mailto:[email protected]] > Sent: Thursday, April 23, 2015 10:14 AM > To: Templin, Fred L; Ronald Bonica; [email protected] > Subject: Re: [Int-area] I-D Action: draft-ietf-intarea-gre-ipv6-07.txt > > > > On 4/23/2015 10:01 AM, Templin, Fred L wrote: > ... > >> I repeat: Probe success tells you only that. Probe loss tells you only > >> that. > >> > >> What "would have" happened is irrelevant. > > > > Then, let me also repeat that "about all you can tell from probing is > > whether > > the egress is alive - probing can't be relied on to tell you anything about > > the > > path(s)" > > We're not doing routing. We're determining whether packets make it to > the egress. > > > Again, this does not make me happy because I have been trying to figure > > out for years how to make tunnels probe the MTU. > > If the probe makes it, it makes it. > > If the probe "would have failed" on another path, you'll either see that > over several probes or not.
Only if you craft your probes in such a way that they eventually test all paths in a multipath arrangement. That might require quite a lot of probes (e.g., if every conceivable flow label value needs to be probed). > If you do, you have what is isomorphic to a > lossy link, It would actually be much worse than a lossy link, because some traffic would receive good service while other traffic would be dropped completely. > and you decide how you want to handle that - if you can > fragment to get around it, then you might try that. Fragmentation works in all cases, AFAICT. > If you have FEC, you > might try that. > > The cause of the losses is irrelevant. Sure, but then probing for a specific MTU size is hopeless. Thanks - Fred [email protected] > Joe _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
