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Configure port mirroring for switch

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

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 chat monitor to capture network traffic of the whole LAN. If you switch doesn't support such monitoring feature, please refer to how to capture others.

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 show the "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 monitor can connect to it.