Nexus 7k HSRP Load Sharing

Ryan Curry · ‎09-02-2011

I'm hoping someone can help me here as I'm trying to wrap my head around N7K and HSRP Load Sharing. If I configure priority on the HSRP group on the Nexus 7K, do the priorities need to be the same to enable load sharing or will it load share by default (better yet, will I need to enable HSRP version 2)?

Thanks All!

Jerry Ye · ‎09-02-2011

HSRP in the N7K will only load shared (A/A) if the VLANs are part of a vPC (a.k.a. vPC VLANs).

If you have vPC VLANs, HSRP priority value is just like a regular set up one higher than the other (i.e. 105 and 100). ARP is handle by HSRP primary, both SVIs on different N7K will forward traffic toward northbound (to the core). Here is a good link to read about how HSRP interact with vPC.

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/white_paper_c11-516396.html

Regards,

jerry

Marwan ALshawi · ‎09-04-2011

Hi

as Jerry mentioned HSRP works in Active/active from forwarding point of view

HSRP MAC of vPC are programmed with the G (gateway) flag on both systems, compared with a non-vPC configuration, only the active HSRP interface can program the MAC address with the G flag.

the Active HSRP in Nexus reply with the virtual MAC of the VIP, this will be the MAC - to HSRP - VIP which will be mapped to both the active and standby from arp prospective and this way they are both in forwarding which is different from other Cisco Devices while in Nexus HSRP virtual MAC is populated into the L3 hardware forwarding tables, making local forwarding capability on the HSRP standby

and about the configuration it is simply same as with normal HSRP just make sure the primary vPC, STP Root to be the Active HSRP ( active will be from control plane point of view only as described above )

HTH

if helpful rate