Nexus 9k Sticky bit is true on Secondary vPC

[manisha.sharma]

we have two Nexus 9k and vpc is running, peer-keepalive link is going from mgmt port to mgmt switch, Peer-link is working on 4 ports 10g.

I am confuse with sticky bit, i turned down the peer-keepalive link (no effect on peer-link) then i broke peer-link (primary remain primary but secondary changed its status to primary optional).

Then i fix peer-keepalive link followed by peer-link, confusion raised here, Sticky bit get true for Secondary (optional Primary) vpc peer and it forced the primary vpc to Secondary optional.

Here is debugging output from Primary:

2017 Apr  6 06:28:15.591330 vpc: Performing election betn local [1, 58:97:bd:0a:23:f1] and remote [32667, ec:bd:1d:62:d9:55], remote sticky [1]
2017 Apr  6 06:28:15.591420 vpc: Local switch is the SLAVE

Debugging output from Seconday:

2017 Apr  6 07:02:35.411999 vpc: Performing election betn local [32667, ec:bd:1d:62:d9:55] and remote [1, 58:97:bd:0a:23:f1], remote sticky [0]
2017 Apr  6 07:02:35.412086 vpc: Local switch is the MASTER

As per Cisco if device get rebooted or replaced then sticky bit will turn to true on secondary device and will force primary device to secondary optional to avoid unnecessary disruption .............am i right or missing any piece of information ?

in my case device was not rebooted, i am into testing so break the links.

Please help me out.

Mani

[eduardopozo56]

From nexus documentation, the behaviour you are experiencing is the normal behaviour upon disconnecting both keepalive and peer-link:

Source:

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/design_guide_c07-625857.html#_Toc271759447

f the peer link is disconnected but the vPC peers are still connected through the vPC peer keepalive link, the vPC operational roles stay unchanged.

If both the peer link and peer-keepalive link are disconnected, both vPC peers become operational primary, but upon reconnection of the peer-keepalive link and the peer link, the vPC secondary device (operational primary) keeps the primary role, and the vPC primary becomes the operational secondary device.