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Client /server outage

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Hello ,

I have issue with TCP/IP server that exchange data with clients dcl (xml) format , the issue occurs once a day , sometimes twice , and goes as follows suddenly all clients cannot connect to the server , while on the server itself, the server is still appear to be listening and seems to be operational , but no connection could be done. During normal communication the data exchange finish with RST deliberately to avoid "TCP Time wait" as attached below Normal communicationhttps://drive.google.com/open?id=0B0a...

image description The server run under Windows 2008R2 , we made sure that firewall and base filtering service is off During the Wireshark trace on it , we can see that prior to the indecent several clients announce Zero Window Clients zero Windowhttps://drive.google.com/open?id=0B0a...

Zero Window Session examplehttps://drive.google.com/open?id=0B0a...

, but i don't know if its related , During the incident we can see clearly that's server kind of rejecting connection but we not sure of the source , since as for server logs seems to operate ok, and he exchange data with others same type of servers during the clients outage as seen blows image. Incident Periodhttps://drive.google.com/open?id=0B0a...

Now we are kind of stucked , and hope someone could pin point something I missed trace is shared here Thanks Please advice

trace Sample

tbaror's avatar
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tbaror
asked 2017-11-06 15:46:14 +0000
sindy's avatar
6.2k
sindy
updated 2017-11-06 16:25:39 +0000
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You have said you close all the sessions with an RST. But in the trace I can see a lot of session wich are closed by a normal FIN handshake?

Christian_R's avatar Christian_R (2017-11-07 04:59:56 +0000) edit
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Hi Christian Thanks for noticing it , you right, on your opinion could it be that server waits for RST and clients for some reason sends FIN can cause that effect ?

tbaror's avatar tbaror (2017-11-07 08:26:06 +0000) edit
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At the moment I can´t say it. As I need to have a deeper look into the tracefile.

Christian_R's avatar Christian_R (2017-11-07 11:39:26 +0000) edit
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1 Answer

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Is there a load balancer in front of your server?

It sounds like one load balancer/or server might fail and clients attempt to go to another load balancer/server which they don't have a valid 3-way handshake for.

If you don't have a load balancer, forget I asked.

wbenton's avatar
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wbenton
answered 2019-08-14 00:34:56 +0000
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