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Slow Transfer Speeds / Hanging - TCP ZeroWindow

0

Hi All,

Looking at the attached diagram - My server is IP 10.x.x.x and the client is on 172.x.x.x.

10.x.x.x Server sits in Our DataCentre. The PC on 172.x.x.x is a DMVPN Site

I have complaints from users at this site when using a system to upload/download files. I have about 20 other sites who use the system also with no complaints. Bandwidth Utilization at the sites is not saturated.

Looking at the screenshot - does this suggest that it is my server having buffer issues? (10.44.145.196)? Trying to decipher what the actual messages are telling me.

Thanksalt text

![alt text][2]

asked 23 Sep '15, 06:32

exit12's gravatar image

exit12
11557
accept rate: 0%

edited 23 Sep '15, 06:33


One Answer:

0

Yes your Server has a full receive window and the client tests if the window is still at the zero size. What is the OS at the server?

answered 23 Sep '15, 09:51

Christian_R's gravatar image

Christian_R
1.8k2625
accept rate: 16%

Hi Christian,

The server side is actually a Linux machine I believe. I've attached another screenshot from the conversation as I just want to understand what each part means.

Looking at packet 4248 - it looks like the server reports a TCP Zero window. What does the 8010 - 63607 numbers represent/mean? Also seen in packet 4305, 4509, 4788.

Thanksalt text

(24 Sep '15, 02:27) exit12

8010 is the Source Port and 63607 is the Destination Port of that packet.

(24 Sep '15, 11:38) Christian_R