Hi, I am struggling to understand why the downloads from this server start off quickly and then suddenly drop to a crawl. I see there are "TCP windo full" messages early on in the trace, but this is only in the first 100 packets and window scaling is enabled. I was testing this by downloading a 20MB PDF file using "wget" from the client, I had to "ctrl-c" the capture to keep it below 1.5MB to be able to upload to cloudshark but I believe there is enough evidence of the issue in the following captures? https://www.cloudshark.org/captures/a9124b6343ce - server https://www.cloudshark.org/captures/e82f6c71e0c1 - client Regards, Elvin asked 05 Dec '14, 08:21 elfelvin |
One Answer:
The problem seems to be in the server not being able to feed the 'pipe' fast enough. So not a network but rather a server problem - I would say... Regards Matthias answered 05 Dec '14, 13:42 mrEEde |
It seems that server send limit is bound to 77380(Bytes in flight never moved beyond this),it could be due to send buffer or congestion window limitation from server end because client offered windows size is quite higher.
Matthias is right, Yes in Middle it looks that server is only sending 8760 bytes/Roundtrip.
So, I've looked at the "server" which is a Citrix Netscaler LB and it looks like the "MEM_TCPBUFFP" value is at 93% usage with ErrLmtFailed values incrementing, so I'm currently in contact with Citrix to get their advise on increasing this buffer (http://support.citrix.com/static/oldkc/CTX116779.html) I'll report back on the outcome.