number of TCP connections

jlearmonth · ‎02-12-2007

Hi,

Sorry if this is a stupid question, but how can I tell the number of active TCP connections that say a switch or router is currently handling? I've tried looking at tcpActiveOpens.0 and tcpPassiveOpens.0 in the MIB, but they don't seem to relate to the traffic. What am I doing wrong?

Thanks,

Jules.

bjw · ‎02-12-2007

Try this reference about passive monitoring of TCP connections using the Cisco TCP intercept function.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fsecur_c/ftrafwl/scfdenl.htm

Other than that there are a few show tcp xxx commands that give some summaries related to tcp connections to/from the router itself.

dominic.caron · ‎02-12-2007

Enable netflow on the router(ip route cache flow on interface), you will be able to get stats like this

sh ip cache flow

Total flow/s

TCP-Telnet 4058396 3.2

TCP-FTP 4871555 3.9

TCP-FTPD 308255 0.2

TCP-WWW 442894669 357.8

TCP-SMTP 35046690 28.3

TCP-X 560729 0.4

TCP-BGP 18331 0.0

TCP-NNTP 519092 0.4

TCP-Frag 28724 0.0

TCP-other 698655766 564.4

If you are using a L3 switch, it's a bit harder.