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Spanning issue on the IDSM.


Can someone advise on the following:

If I've one IDSM on the cat 6500 & with configuration spanning one of the VLAN on the entire LAN, which consists of other Cat6k, Cat4k & Cat3500XL.

Are all the hosts that are connected to all the switches with the particulars spanned VLAN will be monitored OR only hosts connected to the Cat6500 with the IDSM installed are going to be monitored.

Thank you in advance for your kind advices.


Cisco Employee

Re: Spanning issue on the IDSM.

Only packets going through the same Cat 6500 where the IDSM is installed will be monitored.

In most situations that means just packets to and from the hosts directly connected to that switch.

But if that switch is connected between two other switches. Packets passing between those two switches that pass through the IDSM switch will also be monitored.

If you want to monitor all machines on the entire vlan on all of your switches you would need to use RSPAN. RSPAN, however, is only supported in the Cat 6000 (running traditional Cat OS and not native Cat IOS), and later versions of the Cat 4000, but not the Cat 3500.

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