Wireshark

Dec 2 2008   7:30AM GMT

How to configure SPAN(Switched Port Analyzer ) feature in a Cisco Catalyst Switch

Posted by: Yasir Irfan
Switches, Cisco, Switching, Cisco IOS, Wireshark, Cisco 2960, Cisco 2950, Cisco 6500, Cisco Tips, Cisco 3560, Cisco 3745, Cisco Learning, Cisco 3750-E, Cisco 3560-E, Network Troubleshooting, Show commands, Cisco 6500 Series Catalyst Switch, Cisco 6503, Cisco Catalyst 6503-E Switch, Cisco Catalyst 6506-E Switch, Cisco Catalyst 6509-V-E Switch, Cisco Catalyst 6509-E Switch, Cisco Catalyst 6513 Switch, SPAN, Sniifer

It’s quite important for Network Engineers and an essential network troubleshooting technique to utilize the ability of Cisco Catalyst Switches to mirror the traffic and send it to a sniffer for analysis. All Cisco Catalyst Switches support the Switched Port Analyzer (SPAN) feature. The SPAN copies traffic from the specified interface or VLANs and mirrors this traffic to a specified destination interface (SPAN interface).  Then you can connect the PC with a sniffing tool (Wireshark) installed on the destination SPAN interface to capture all the mirrored traffic.Let’s see how to configure the SPAN in Cisco Catalyst Switches.  To enable the switch SPAN mirroring feature configure the following on the catalyst switch: Configuration Example - Monitoring traffic from a specific interfaceITKEAS01#configure tITKEAS01(config) monitor session 1 source interface gigabitEthernet 0/5

ITKEAS01(config)#monitor session 1 destination interface gigabitEthernet 0/10 

The  above configuration will capture all traffic from interface gigabitEthernet 0/5  and send it to SPAN port interface gigabitEthernet 0/10 

Configuration Example - Monitoring an entire VLAN traffic
ITKEAS01(config)#monitor session 1 source vlan 100
ITKEAS01(config) monitor session 1 destination interface gigabitEthernet 0/10 The  above configuration will capture all traffic of VLAN 100 and send it to SPAN port interface gigabitEthernet 0/10

Use  show monitor session 1 to verify your configuration.