Vpc Peer Switch Failure; Vpc Peer Link Failure Followed By A Peer Keepalive Link Failure; Vpc Keepalive Link Failure Followed By A Peer Link Failure - Cisco Nexus 5000 Series Operation Manual

Chapter 1 Virtual Port Channel Operations
S e n d d o c u m e n t a t i o n c o m m e n t s t o n 5 k d o c f e e d b a c k @ c i s c o . c o m
Note
If this scenario occurs again or if the keepalive link goes down after vPC peers are established, the roles
do not change and all vPCs remain up.

vPC Peer Switch Failure

When one peer switch fails, half of the network bandwidth is lost and the remaining vPC switch
maintains the network connectivity. If the failure occurs on a primary switch, the secondary switch
becomes the primary switch.
When one peer switch fails, the remaining peer switch maintains network connectivity for the vPC until
it is reloaded. This situation could happen if both vPC peer switches are reloaded and only one switch
comes up or both switches loose power and then the power is restored only on one switch. In either case,
since the vPC primary election cannot proceed, the Cisco Nexus 5000 Series switch keeps the vPC ports
in suspend mode.
To fix these problems, use the reload restore feature and the auto recovery feature as follows:
In NX-OS Release 5.0(2)N1(1), enter the reload restore command:
switch(config-vpc-domain)# reload restore <timeout in second>
In NX-OS Release 5.0(2)N2(1), enter the auto-recovery reload-delay command:
switch(config-vpc-domain)# auto-recovery reload-delay ?
<240-3600>
These commands allow the vPC peer switch to bypass the vPC consistency check and bring up vPC ports
after the delay timer expires.

vPC Peer Link Failure Followed by a Peer Keepalive Link Failure

If a peer link failure occurs, the vPC secondary switch checks if the primary switch is alive. The
secondary switch suspends its vPC member ports after it confirms that the primary switch is up.
If the vPC primary switch goes down, the vPC secondary switch stops receiving Keepalive messages on
the vPC Peer Keepalive link. After three consecutive Keepalive message timeouts, the vPC secondary
switch changes its role to be the vPC primary switch and brings up its vPC member ports.
In Cisco NX-OS Release 5.0(2)N2(1), if you enable the auto-recovery feature and if the vPC primary
switch goes down, the vPC secondary switch does not receive messages on the vPC peer keepalive link.
Then, after three consecutive keepalive timeouts, the vPC secondary switch changes its role to primary
and brings up the vPC member ports.

vPC Keepalive Link Failure Followed by a Peer Link Failure

If the vPC keepalive link fails first and then a peer link fails, the vPC secondary switch assumes the
primary switch role and keeps its vPC member ports up.
If the peer link and keepalive link fails, there could be a chance that both vPC switches are healthy and
the failure occurs because of a connectivity issue between the switches. In this situation, both vPC
switches claim the primary switch role and keep the vPC member ports up. This situation is known as a
Time-out for restoring vPC links (in seconds)
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
vPC Failure Recovery
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