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6509 Sup2+MSFC2 Configured with More Than 16 Unique HSRP Groups

We are in progress in designing a LAN infrastructure for a customer who has bought 1x 6509 with 2x SUP2+MSFC2. The customer would like to have around 30 VLANs, each with IP/IPX routing enabled.

HSRP groups will be configured for each VLAN between the 2 MSFCs to provide redundancy, however we found out that the SUP2/PFC2 only supports 16 unique HSRP groups. Therefore we'll have VLANs that have its corresponding HSRP group number duplicates with other VLANs as well as the virtual MAC address.

For detail, please refer to

Unfortunately at the early phase, the customer has an AS400 system which still runs on DLC. They will migrate the AS400 to run on TCPIP ultimately but this is not gonna happen within these few months, so we will have to enable bridging on MSFC and run IRB, so as to provide bridging of DLC among all VLANs.

But according to the documentation as stated in the above web link, "Identically numbered HSRP groups use the same virtual MAC address, which might cause errors if you configure bridging on the MSFC." However, the docuemtation doesn't mention what exactly the error will be. During our small scale pilot test, we didn't experience any strange problem with only 1 SUP2+MSFC2 installed.

Does anyone have prior experience with similar situation and know what error might occur as said in the doc? Any expertise to re-assure the above design? Many thanks.

New Member

Re: 6509 Sup2+MSFC2 Configured with More Than 16 Unique HSRP Gro

We are running twin 6509's sup2/msfc2 trunked together and using hsrp for redundancy/failover. We currently do not have any bridging enabled but have at the present time over 27 vlans configured and they are working very well. Our Cisco SE told me not to really worry about the 16 unique hsrp groups but as stated before we are not doing bridging..hope this helps.


Re: 6509 Sup2+MSFC2 Configured with More Than 16 Unique HSRP Gro

Don't believe this is a problem , we currently probably have at least 50 vlans on a 6509 each with it's own hsrp group with no problems .