Upgrade MCT Leaf Pair with Dual Homed Servers in Clos

  1. Enabling maintenance mode on an MCT leaf involves BGP and MCT/NSM. The graceful_shutdown parameter will be sent out to all the leaf‘s underlay neighbors (all spines in the pod). The neighbors will no longer send traffic to the MCT leaf going into maintenance mode and redirect traffic from spines to the peer MCT leaf. MCT will instruct the peer leaf to become the designated forwarder, ICL will be shut down, and CCE ports for clients will also be shut down. Traffic from dual-homed servers will be redirected to the peer leaf. With maintenance mode enabled, traffic is completely redirected to the peer leaf.
  2. The running-configuration is saved on the first MCT leaf to preserve all current configurations including the maintenance mode enable configuration.
  3. The firmware on the MCT leaf can now be upgraded and rebooted for firmware activation without traffic loss.
  4. After the firmware is upgraded, the maintenance mode is disabled to allow traffic again through the upgraded MCT leaf.
  5. The running-config is saved again to ensure the maintenance mode config remains disabled.

    The same process can be carried out on the second MCT leaf to upgrade the firmware without traffic loss.

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    First MCT leaf firmware upgrade with maintenance mode
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    Second MCT leaf firmware upgrade with maintenance mode
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