Justin, The group number sets the virtual MAC address assigned to that group. If you have some transparent L2 infrastructure (such as a VPLS domain you try to transit) this could cause issues, and using different groups per different VLANs is critical. In most other cases there is no need to change group numbers between VLANs.
Take a look here: http://www.cisco.com/en/US/docs/ios/ipapp/command/reference/iap_s2.html# wp1073440 Another point is that you can use HSRPv2, which extends the group number to 4096: http://www.cisco.com/en/US/docs/ios/ipapp/command/reference/iap_s3.html# wp1063204 Arie -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Justin Shore Sent: Monday, December 22, 2008 21:19 To: 'Cisco-nsp' Subject: [c-nsp] Sharing HSRP group numbers across multiple HSRP instances I have a situation in which I'm wondering if I can use the same HSRP group number for multiple SVIs on a pair of 7600s. The VLANs all perform similar functions in groups of 3; outside of FWSM contexts, inside of FWSM context, SVI for terminating client IPSec VPNs. Ie, each customer has 3 VLANs that perform these functions. I have multiple customers and each has 3 VLANs in VRFs (where applicable) on my 7600s carved out for these specific functions. Can I use the same HSRP group for each of the individual 3 VLANs across multiple customers? ie: Customer VLAN Purpose ------------------------------- 1 1501 Outside 1 1601 Inside 1 1701 CVPN 2 1502 Outside 2 1602 Inside 2 1702 CVPN 3 1503 Outside 3 1603 Inside 3 1703 CVPN Purpose HSRP Group --------------------------- FWSM outside 100 FWSM inside 101 CVPN 102 VLANs 1501-1503 get group 100, 1601-1603 get group 101, 1701-1703 get group 102. Each customer VLAN performing that specific role shares that HSRP group #. That's worded better. All VLANs share the same L2 infrastructure (actually they never leave the 7600s). Is this doable or should I just use HSRPv2 and one of the 4096 group #s available to me? Would sharing group #s result in few HSRP hellos send and processed, thus lower RP overhead? Just curious. Thanks Justin _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
