WAN ECMP to Nexus 7K

[robert.horrigan]

Hi,

I have a Nexus 7K deployment with dual layer3 to 7600 WAN routers.  One 7K switch is root for all Vlans and HSRP primary for all Vlans which is my understanding of best practices.  My question is -

Will the secondary Nexus 7K ever be used for WAN communications?  Since S01 is the default gateway, wont all traffic always use the first switch?  I've attached a diagram below.  The design practices say to configure ECMP and that will ensure loadbalancing across all WAN uplinks, but I do not quite get it....  I would think I would need to split the HSRP primaries for SVIs across nexus switch1 and switch2 to achieve this.

I appreciate any insite into this configuration.

/r

Rob

[Jerry Ye · Accepted solution]

In N7K, HSRP in the vPC VLANs will forward traffic to its up stream if there are ECMP. ARP request will be handled by the HSRP primary, while both HSRP active and standby router will forward traffic to its upstream if the route is equal cost.

Please take a look at this link vPC Layer 3 Interaction section

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

HTH,

jerry