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Re: Can you explain why paths to same host diverge?
John, Thanks very much for providing the cogent explanation. You ask: >I feel obligated to ask -- is there some reason you didn't >direct your query to Sprint, before asking NANOG? It really seems like >this is the kind of question they should be able to answer for you, >and diagnose the problem to some extent. I can't see a good reason to ask >here without asking the providers in question, first. There were really two reasons I asked this question here. First, it seemed like an interesting operational issue that I hadn't ever seen beaten to death on NANOG. Everyone is used to asymmetry between forward and reverse paths, but I don't think I'd ever seen a case of asymmetry in the forward path (at least, not while the network was stable). Second, I don't necessarily expect my provider to tell me why things route the way they do; I only expect them to fix things when they're broken. NANOG seems the appropriate place to ask the "why" questions. For what it's worth, I am pursuing this with our provider. >It is worth noting, I suppose, that optioned packets (i.e. traceroute -g >or ping -R) are not CEF-switched, and therefore cannot be used to >instrument the behavior of this hash. As a result, your best bet is >limited ttl probes to various hops. Presumably this is why the reverse traceroutes I ran didn't seem to shed any light. Thanks again for the end2end-interest pointer and the fine explanation. regards, mb -- Mark Boolootian firstname.lastname@example.org