sniffing on a switch based network

[tato386]

Using network monitor and/or sniffer is impossible these days because of the popularity of switches. I usually carry a small hub with me so that I can connect routers and other devices to the same collision domain as my sniffer. What is going to happen when my hub dies and I can't buy another? What techniques can I use to troubleshoot using a sniffer on a switch based network?

Thanks,

Diego

[donewald · Accepted solution]

Diego,

Most switches have a port mirroring capability these days to get around the switching functions to allow for sniffers to work properly. Cisco calls this function SPAN (switch port analyzer). Check out this link on SPAN.

http://www.cisco.com/en/US/partner/products/hw/switches/ps679/products_configuration_guide_chapter09186a008007ef1f.html

There is also RSPAN as well if you are interested in this feature.

Hope this is what you were looking for,

Don

[tato386]

Looks like what I need.

Thanks!

Diego