Best practices for enabling multicast traffic for Red Hat Cluster Suite on Cisco Catalyst switches

Solution Verified - Updated

Environment

  • Red Hat Cluster Suite 4+
  • Red Hat Enterprise Linux Server 5 (with the High Availability and Resilient Storage Add Ons)
  • Red Hat Enterprise Linux Server 6 (with the High Availability and Resilient Storage Add Ons)

Issue

  • Nodes do not receive traffic being sent by other cluster members during bootup, which may result in a non-quorate cluster or a split brain scenario

  • There is a delay before network requests for nodes can be serviced.

  • Each node shows itself as online and the other(s) as offline.

  • Nodes are fenced during bootup.

  • Nodes are only able to form a cluster when CMAN is started manually, but not when started as part of the boot process.

  • Only one node is able to bring its cluster services online, while other nodes print messages similar to:

      openais[1234]: [CMAN ] cman killed by node 1 because we rejoined the cluster without a full restart

Resolution

See the following tech brief: How to Avoid a Split-Brain Scenario with Cisco Switches by Enabling Multicast Communication

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