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New Member

SPAN feature on Catalyst 2924 XL and 3524 XL switches

For both Catalyst 2924 and 3524 switches, SPAN can be configured using

Switch(config-if)# port monitor vlan/interface command.

However, I have noticed that this command works only for VLAN 1 and Cisco documentation I looked at also suggested the same.

Is this an IOS limitation or a SPAN limitation?

The Catalyst 2924XL I have has [IOS ver: 12.0(5)WC5a] and Catalyst 3524XL has [IOS ver: 12.0(5.4)WC(1)]

Please advise.



  • Other Network Infrastructure Subjects
New Member

Re: SPAN feature on Catalyst 2924 XL and 3524 XL switches

I believe with the 2924 series the port you are trying to span, and your monitor port have to be in the same VLAN. We do this all the time with 2924's running 12.0(5.2)WC1 software and earlier.

For instance, lets say your sniffer was attached to port 1 and port 1 is normally in VLAN 1 but the port you are trying to monitor is port 20 and it is in VLAN 2. You would need to put port 1 in VLAN 2 first, then configure your monitor port.

Hope this helps....


New Member

Re: SPAN feature on Catalyst 2924 XL and 3524 XL switches

Thanks but I have noticed that when I want to monitor a VLAN and configure a switch port to be in that VLAN and set it up for port monitor it does not work any other VLAN apart from VLAN 1.

For example,

Switch2924-150011(config)#int Fastethernet0/4

Switch2924-150011(config-if)#switchport access vlan 24

Switch2924-150011(config-if)#port monitor vlan 24


% Invalid input detected at '^' marker.

New Member

Re: SPAN feature on Catalyst 2924 XL and 3524 XL switches

OK. Now I understand. This is the same mistake I made at first when working with the 2900xl series of switches.

The 'vlan' concept in the 2900 is the management interface, not referencing the ability monitor VLAN #1. But rather you are specifying to monitor the *interface* VLAN1 (the ip address of the actual switch - you will see only traffic to and from the management interface of the switch -such as your own telnet session).

Span configuration on the 2900's is done entirely by port number. So, lets say you wanted to monitor the entire VLAN 2. Port fa0/1 is the interface where your sniffer is and VLAN 2 includes interfaces fa0/5, fa0/6 and fa0/7. You would go into interface mode on interface fa0/1 (where your sniffer is) and tell it to monitor interface fa0/5, fa0/6 and int fa0/7. There is no way to tell a 2900 series switch to monitor an entire VLAN....bummer.

Best of luck.

Sorry to misunderstand your initial question.

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