In the Cisco Nexus 1000V switch, if a VSM is configured or installed with the same role as the existing VSM and with the same domain ID, the new VSM and the existing VSM exchange heartbeats to discover each other. Both the VSMs detect a role collision upon processing the exchanged heartbeats.
Due to this issue, the remote management component, VEM, and the HA-paired VSM cannot communicate with the correct VSM. This issue can occur on a primary or a secondary VSM depending on whether the newly configured or the installed VSM has the primary or the secondary role assigned to it.
The collisions are detected on the control and the management interfaces. The number of role collisions is restricted to 8.
The colliding VSMs may also report a collision detection from the original VSM. Since the colliding VSMs may use the same IP address for their management interfaces, the remote SSH/Telnet connections may fail. Therefore, we recommend that you use the consoles during a role collision detection.
After the successful high availability configuration, execute the CLI command show system redundancy status on both primary and secondary VSM consoles. When the colliding VSM stops communicating in the domain, the collision time is not updated anymore. After an hour has elapsed since the last collision, the collision MAC entries are removed.
An appropriate action, for example, changing the domain or shutting down the switch, should be taken on the colliding VSMs to ensure the proper operation of the Cisco Nexus 1000V switch.