[Bloat] delay-under-load really helps diagnose real world problems

["Bill Ver Steeg (versteb)" <versteb@cisco.com>]

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So, I have been suffering from pseudo-random performance problems for several months. I tend to travel quite a bit, and use VPNs from several networks. I occasionally suffer from crappy web performance, but the old tools did not provide much useful info. My un-VPNed network speeds were x (where x was site specific and typically about 60 Mbps) and my VPN-ed speed were about 50 Mbps.

It seems that at one site I had occasional web surfing and Webex problems when not on the VPN, but when I got on the VPN from the same site it was OK.

At a different site, I had the opposite problem. I had sporadic problems on the raw network, but seemed to run OK on the VPN.

Well, running the new DSLReports cleared it right up. On the site where I had problems on the raw network, the report said I had ~60 Mbps of throughput - but my delay under load spiked as high as several seconds. When I fired up the VPN, the VPN became the bottleneck link at ~50 Mbps. The VPN had reasonable (not great , but reasonable) buffer sizes, and my delay was ~150ms.

On the site where I had problems on the VPN but the raw network ran OK, I found that the 50 Mbps VPN introduced several seconds of delay under load. It looks like the PoP that I use in that geography has something misconfigured with a huge buffer, and I suffer bloat when it gets congested.

I am running these things down with the various owners, which should prove to be an interesting experience.......

So, hats off to Justin!

Bill VerSteeg

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