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100+ VLANs on Sup1/MSFC1s

We have a required for adding around 100+ sites, all connected via 10Mbps LAN-extension services to our core network. Instead of placing a router at each remote site and performing edge-routing, we are considering moving the routing to the core of the network (two 6509s fitted with dual Sup1A/MSFC1s), and terminating the 100+ sites in their own VLAN, defined on the MSFCs. The MSFCs require identical configurations for HA, which therefore means the 100+ VLANs must be defined on all MSFCs and 100+ 4-way HSRP groups will therefore be required (one HRSP group for each VLAN). At some point in the future, we may need to provide other services to these sites (e.g. VoIP), so there is the strong possibility that more than one VLAN per site will be required. We are strongly considering upgrading the Sup1A/MSFC1s to Sup2/MSFC2s to terminate the larger number of VLANs; would this be a wise move? In addition, these 100+ sites will require a different default route to that of the existing network, which would mean policy routing all inbound traffic on these VLANs to a specific next-hop address for traffic which is not destined for our network. Can the Sup2/MSFC2 policy based routing be performed in hardware (where the policy route-map is likely to include a 'match' clause based on an extended access-list entry)?

New Member

Re: 100+ VLANs on Sup1/MSFC1s

Yes.. the upgrade to a Sup2/MSFC2 is definitely recommended. Depending on how many per-destination flows of traffic you have, the Sup1/MSFC1 may begin to run out of HW shortcut caching space on its PFC1.

The PFC2 on the Supervisor2 does not have this limitation as it is using topology-based lookups (HW CEF) rather than flow-based.

Regarding HA, if you have 2 Chassis with 2 Sups/MSFCs in each, why not consider SRM (Single-router mode)? That way, you do no have to have the 4-way HSRP group scenario, and just the standard 2-way HSRP with SRM redundancy on the same chassis - this works really well!!

Also, with PBR, yes - we do support PBR in hardware on the Supervisor 2 as long as we match on an ACL and set ip next hop.


Re: 100+ VLANs on Sup1/MSFC1s

Thanks for your reply. SRM is certainly an option, though it may be more desirable to load-balance the VLANs across the four MSFCs, with these new 100+ VLANs across a pair of MSFCs and the remainder of the network distributed across the other pair of MSFCs (though all VLANs would be defined on all MSFCs, and HSRP priorities selected to give the required load-balancing). Is it possible to create more than 256 HSRP groups, as this would seem to define the limit of VLANs defined on the Sup2/MSFC2 (where a single HSRP group maps onto a single VLAN)?

New Member

Re: 100+ VLANs on Sup1/MSFC1s


I'm trying to configure Multiple HSRP groups in mSUp1/MSFC1. What is the maximum number of HSRP Groups I can configure.


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