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New Member

MARS and Layer3/Layer2 Switches


It is common in the medium buisness to use a large chassis switch (or a pair of them) for both Layer 3 inter-VLAN routing and also Layer 2 port aggregation. For example, a 6513 with 200 hundered triple-speed ports for servers and desktops and also intervlan routing for 30 VLANs.

How does MARS deal with this? Is it a Layer 2 device as in "Cisco Switch-IOS 12.2" or is it a Layer 3 device "Cisco IOS 12.2"? Does it matter? (I always run native mode so there is not a seperate interface for the MSFC3).


Re: MARS and Layer3/Layer2 Switches

Whatever it is, you will have to enable syslog on the MSFC and bundle it with the MARS. the logging level you set, gives whatever info you require.. MARS will collate all these info and give you an event correlation report.... Is this OK?


New Member

Re: MARS and Layer3/Layer2 Switches

As far as I know, you'll have to add the MSFC3 device and configuring like Raj says. Then, you can add the Layer 2 Cisco switch as a "Cisco Switch-IOS 12.2" and you'll see there's an option for "Add Available Module". Look for the MSFC3 device created previously and add it.

Anyway, it's correct what Raj is saying. Don't worry too much because MARS will correlate the events.

Good luck!!

ps: Rate the post if it helped you.

New Member

Re: MARS and Layer3/Layer2 Switches

I understand how MARS correlates messages. MARS also needs to understand the topology of the network at Layer2 and at Layer3. The switch is both a Layer2 device and a Layer3 device.

In native IOS mode, a 6500 switch and the onboard MSFC are managed with one interface. You can not add the "switch" into MARS as one device and the MSFC as a second device. They are the same interface, the same device.

You can not add an MSFC as a module. The only options are FWSM and IDSM.

So the question remains: Do I add this switch into MARS as a "Cisco Switch-IOS 12.2" or a "Cisco IOS 12.2"? Will it matter with regards to Layer2 and Layer3 topology calculation?



Re: MARS and Layer3/Layer2 Switches

Maybe I'm missing something (we don't have those devices in CSMARS) but doesn't this answer your question?

It appears that you add it as a switch and then add the modules.

New Member

Re: MARS and Layer3/Layer2 Switches

I added the 6500 as a "Cisco Switch-IOS 12.2" and MARS does see the many IP subnets that hang off of the MSFC. So it appears to be able to determine that the switch is not just functioning at layer2.

It is a little confusing in that MARS wants a device to be layer3 (Cisco IOS 12.2) or layer2 (Cisco Switch-IOS 12.2) and in some cases a single device is functioning as both.

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