Nexus VPC Dual active Detections

[vinoth13.c]

Hi All,

can somedbody give good example of VPC dual active Detection in Nexus VPC .

if Peer-keepalive and peer-links goes down , what will happend at that time ?

thanks

vinoth Kumar C 

[Flavio Miranda]

Hi,

Dual Active Detection is more suitable for VSS.

About vPC:

1. If vpc peer link down, 2ndary peer suspends local vpc and shutdown svi's of vpc vlan.

2.if the vpc peer keep-alive link fail it has no impact in our environment but we need it to bring the system up.

3. if both down. it will turn primary/primary

-If I helped you somehow, please, rate it as useful.-

[Andrea Testino]

Hi,

The multiple vPC failure scenarios are documented in Page 126 of the vPC Best Practices  - You are asking specifically for what happens when the PKA and PL go down:

• vPC keepalive link failure followed by a peer link failure

"If the vPC keepalive link fails first and then a peer link fails, vPC primary switch continues to be primary but the vPC secondary switch becomes the operational primary switch and keeps its vPC member ports up (this is also known as dual active scenario). This can occur when both the vPC switches are healthy but, the failure is occurred because of a connectivity issue between the switches. This situation is known as a split-brain scenario. There is no loss of traffic for existing flows but new flows can be effected as the peer link is not available, the two vPC switches cannot synchronize the unicast MAC address and the IGMP groups and therefore they cannot maintain the complete unicast and multicast forwarding table and there may be some duplicate packet forwarding."

Hope that helps.

- Andrea

[vinoth13.c]

thanks for the reply 

i have checked in the document . 

theres two thing ,

vpc failure scenarios

vPC peer link failure

if peer-link is failure, secondary vpc shuts  down all of its vpc member ports , still primary switch as a primary and continuing  forward the traffic

if keepalive link failed followed by peer-link failure ..

When the vPC peer link fails after the vPC peer keepalive link failure, the secondary switch assumes the role of operational primary. This leads to split brain scenario.

i have confused based on the document ...