Hi All,

I'm interested in building something simple with tcpdump that I could use on occasions to plot application latency against several external memcached servers.

IE - I have a webserver connecting to several different/unrelated memcached servers (and I have no access to the memcached servers). I don't want to change the code that's running on the web server making calls to the memcached servers, but I still want to get statistics for the speed of requests from the webserver to memcached.

I think a good way to do this might be by running a tcpdump for a short period of time capturing the packets between webserver and the external memcached boxes (so essentially just capturing packets on the 11211 port for memcache). I'd like to use that data to then graph stats such as the duration of each request.

I've been looking into wireshark, tcpstat, tcptrace, pt-tcp-model xplot. I'm still not yet sure any of these can do what I'm after.

Any guidance would be great,
Thanks,
M

Have a look at tsharks read filter "tcp.analysis.ack_rtt".

*It would be helpful to next time explain 0) why you would not want to change the code that's running on the web server making calls to the memcached servers or 1) why you have not requested either access to the memcached servers or 2) why you have not requested them to provide a restricted access read-only interface for reading stats (better).