TCP retransmissions

[santoshdpawar]

Hi,

I have been facing tcp re-transmit issues reporting in an optimization application. The optimization application is not used for performing optimazation as such but only reporting purpose. Can some one please tell me if how can we identify tcp retransmit at router/switch level as not sure what is configured at optimization app.

Thanks & regards,

Santosh P

[Richard Burts]

Santosh P

There is not a way at the router or switch level to identify a TCP retransmission. Identifying TCP retransmissions would require maintaining state information in the router or switch, including the sequence number of the last packet. If you had the sequence number of the last packet you could check that against the sequence number of the current packet to see if they were the same. But in general Cisco routers and switches do not maintain the sequence number of the last packet. Some of the optimization products do maintain the sequence number but the normal router or switch do not maintain it.

HTH

Rick

[ebarticel]

You may have to capture traffic on that segment while the application is running and study the traffic after.

Eugen