SPAN Configuration for Cisco

Unlike hubs, switches usually prevent promiscuous sniffing. In a switched network environment, a sniffer is limited to capturing broadcast and multicast packets and those traffic sent or received by the same PC as the sniffer running one. 

However, most modern switches support SPAN, or called "port mirroring", which is an advanced feature that enables switches to forward all packets to one or more switch ports and allows sniffers capture network traffic of the whole LAN. If you switch doesn't support such monitoring feature, please refer to Q5 in our FAQ page. 

Here is a 3-step instruction on how to configure SPAN for Cisco Catalyst 1900 Series Switch.

1.Log on to the web manager for your switch. 

2.Click on the "SPAN" link at the top of the web page, and showthe "SPAN Configuration" page.

3.Select a monitoring port and add all the ports to be monitored. In this case, we set the port "Ethernet8" as monitoring port and the computer running sniffers can connect to it.