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Re: Phantom packet loss is being shown when using pathping in connection with asynchronous routing - although there is no real loss.
"Gunther Stammwitz" <[email protected]> wrote:
I have customers who are complaining about packet loss and they areTry varying the mtr interval, such as "-i .1" (must be root for <1). Does the packetloss significantly increase with this faster mtr? Try slower "-i 10". Does the packetloss significantly decrease or go away?
If the answer to both above questions is yes, then I would suspect ICMP rate limiting.
You could also try varying the speed of ping. Windows is pretty limited, but on unix you can do things like .1 second intervals ("-i .1" as root). Does a faster ping trigger this apparent loss? If so, ICMP rate limiting.
The only part that I don't get is that you can mtr to him without packetloss. Although the path in-between may be different, the final hop packetloss should exactly equal what he sees when mtring you. A round-trip is a round-trip, and results should be identical regardless of who originates. I can't think of any way this would be different unless echo and echo-reply were being rate limited independently.
My home ISP (apartment ethernet "t1" service, which is actually multiple T3s) has a Packeteer or something along that line. If I use ping, everything is fine since it goes so slow. If I use MTR, it works fine for the first few seconds then sees >90% packetloss on all hops from then on once the rate limiter burst bucket runs dry. Of course, TCP still sees no packetloss even when mtr is seeing this heavy rate limited loss...