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Redundant MSFCs in Non-redundant config?

What I'm curious about is this. Can I use the two MSFCs in my 6509 independently of each other if I don't care about intra-chassis redundancy?

For example: Could I have MSFC1 routing vlans 1-5 and MSFC2 routing vlans 6-10 and then use vlan 11 between MSFC1 and MSFC2 to exchange routing information between the two MSFCs?

From reading the docs it looks like I might run into to problems with the designated MSFC concept used by the chassis but I'm wondering if anyone has tried this.

I'm using Sup1A with msfc.


Re: Redundant MSFCs in Non-redundant config?


You can use dual router mode for Sup1a, but I believe it has to be in hybrid mode (i.e. CatOS on the Sup and IOS on the MSFC). A good document on how to configure dual router mode is here:

Thank you,


Cisco TAC

New Member

Re: Redundant MSFCs in Non-redundant config?

Hi Michael,

Thanks for the quick response.

I am indeed in hybrid mode so I have that part covered. I understand that I can adjust the HSRP priorities on MSFC1 and MSFC2 to achieve a load balanced + redundant situation. This obviously entails having an interface from both MSFCs on the same vlan.

What I'm curious about is whether having a completely different set of vlans on each msfc with one common vlan for exchanging routing information between them will work. The documents seem to indicate that having non-matching configs on two MSFCs in the same chassis creates "instability".

What I'm trying to do is isolate traffic in my lab from the router that services my data center. Currently, my lab and data center are routed through the same MSFC. We frequently get broadcast storms on the lab network which swamp the CPU on the msfc causing slowdowns in the data center as well. I'm wondering if, instead of buying a separate router to isolate the lab and it's networks, I can use the secondary MSFC in my core switch to keep the lab traffic off of the data center router's cpu.

I'm probably way out on a limb with this but I thought maybe someone had tried it before and might have some experience trying to do it.