Implementing and Operating Cisco Data Center Core Technologies: Cisco Nexus 7000 Series Switch Chassis Replacement and Preventing vPC-Enabled LACP Port Channels Reinitialization

Preventing vPC-Enabled LACP Port Channels Reinitialization

Question

After a Cisco Nexus 7000 Series Switch chassis replacement, the administrator discovers that all vPC-enabled LACP port channels are reinitialized.

The administrator wants to prevent this issue the next time the chassis is replaced.

Which two actions must be taken to meet this requirement before the isolated device is reloaded? (Choose two.)

Answers

Explanations

Click on the arrows to vote for the correct answer

A. B. C. D. E.

AC.

In a vPC (virtual Port Channel) topology, two Nexus switches act as a single logical switch to a downstream device. The vPC feature allows multiple physical links to be bundled together and presented to downstream devices as a single logical link. This provides redundancy and load balancing in the network.

When a Nexus 7000 Series Switch chassis is replaced, there is a risk that all vPC-enabled LACP (Link Aggregation Control Protocol) port channels will be reinitialized. This occurs because the vPC system-id, which is derived from the chassis MAC address, is used as the LACP system-id. If the new chassis has a different MAC address, the system-id changes, and LACP reinitializes.

To prevent this issue from occurring in the future, there are two actions that must be taken before the isolated device is reloaded:

  1. Change the vPC system-priority of the replacement chassis to a higher value than the peer. The vPC system-priority is used to determine which switch is the primary vPC peer. The switch with the lower system-priority becomes the secondary peer. By setting the system-priority of the replacement chassis to a higher value than the peer, it becomes the primary peer after reload. This ensures that the vPC system-id remains the same, and LACP port channels are not reinitialized.

  2. Set the vPC MAC address to a higher value than the peer. The vPC MAC address is used to derive the vPC system-id. By setting the MAC address of the replacement chassis to a higher value than the peer, it becomes the primary peer after reload. This ensures that the vPC system-id remains the same, and LACP port channels are not reinitialized.

Therefore, options A and B are correct answers.

Option C, configuring auto-recovery to the disable state on both peers, is not relevant to the issue of vPC-enabled LACP port channels being reinitialized after a chassis replacement.

Option D, setting the vPC MAC address to a lower value than the peer, will cause the secondary peer to become the primary peer after reload. This may cause issues with vPC convergence and is not a recommended solution.

Option E, changing the vPC system-priority of the replacement chassis to a lower value than the peer, will cause the secondary peer to become the primary peer after reload. This may cause issues with vPC convergence and is not a recommended solution.