analyze the slow application

[Mary]

we are able to connect to the remote server, there are three application running on the server, two of the application are working fine, the third application is very slow, we get the tcpdump and analyze using wireshark, may i know the steps to analyze the slowness for this specific application in wireshark? what should be the tcp sliding window size? thanks

[Deepak Kumar]

In the Wireshark, there are many filters like application port number, Source IP address, Protocol Name or number etc. I hope it is easy for you to check with Port number and source and destination IP address.  

Please check any RESET flag, TCP retransmission and reply (ack) packet and packet size. 

But application performance it depends on many factors as your server, application its self, application API, client system settings, firewall (internal, server, client), mtu size (many more) etc.

Please check all.

Regards,

Deepak Kumar 

[Mary]

I want to check whether small mtu cause the problem, in the tcp syn ack packet, i only find mss, no mtu,

how to find mtu and where to find  there is fragment and retransmission, in tcp or ip or fram portion?

[Deepak Kumar]

Please visit following links, I hope this will helpful for you.
https://blog.packet-foo.com/2014/05/the-drawbacks-of-local-packet-captures/
http://packetlife.net/blog/2008/aug/18/path-mtu-discovery/

Regards,
Deepak Kumar