I had a wee job to do for a friend last week. It was simple enough: add HSRP to four Nexus 5548 boxes on several of the SVIs.
Well, for the life of me I couldn't get it to work properly. Routers couldn't find their standby routers, failover was slow, ping times were huge, > 10ms between the boxes! On and on the problems went.
The boxes all the had the Layer 3 daugter cards installed, and basic routing worked. One very interesting thing I saw in the routing table, was that the routes had 'pending' listed as an attribute. It was late and I'd spent two hours looking at this and we decided to call it a night. Fresh eyes in the morning was to be the solution
The Actual Solution
With fresh eyes we looked once again at the box. 'show license usage'. Whoops, the layer 3 base license wasn't installed!
N.B!. For Layer 3 functionality on the Nexus 5K, you must have two things; the daughter card (Nexus 5548)/Layer 3 Module (Nexus 5596) and the base licenses (or enterprise license) installed.
Without the licenses installed, you'll see all sorts of bizarre stuff!
Also Worth Noting
There is a bug in NXOS code earlier than 5.1.3 n1.1 whereby routers running HSRP with Static routes and vPC and in standby have the active router's MAC address pointing to themselves. This of course will black hole traffic. For more information look at Cisco's Bug Report for the Nexus HSRP Issue