On Thu, Jul 2, 2015 at 1:37 PM, Edward Ned Harvey (lopser) < lop...@nedharvey.com> wrote:
> > From: tech-boun...@lists.lopsa.org [mailto:tech-boun...@lists.lopsa.org] > > On Behalf Of Ross West > > > > Almost all network circuit load balancing systems use some kind of > > (src/dst) hash in order to attempt to keep end-to-end packet ordering > > the same. What the hash is built upon (ip, tcp/udp port, etc) is up to > > the local admin. > > > > So if one path is borked and sending packets to a blackhole (but the > > dynamic routing doesn't detect that), then you'll see things like what > > you mention. > > Thanks - Since this exactly explains the observed behavior, I'm going to > declare it as probably the answer. You get points. ;-) > > The borked network segment could have been inside amazon, or anywhere > between amazon & my colo. It could have been completely borked - and > occasionally the routing protocols would rebalance and route around it - or > it could have actually been intermittent, but consistently routed Host B's > packets onto the intermittent link. > One way to possibly see these alternate paths is to use traceroute rather then ping. Unfortunately, it will only tell you about the outgoing path; but it still might catch something like this. Bill Bogstad
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