ACMP – Exam Notes – Introduction to Clusters – Part 1

What is clustering?

A cluster combines multiple managed devices to provide high availability for all clients.

  • Benefits include seamless roaming
  • Client and AP load balancing
  • Stateful failover
  • Seamless cluster upgrades

Note: ArubaOS 8.X does NOT support the clustering of the mobility conductor. Clustering is only for mobility controllers, virtual mobility controllers in a mobility conductor deployment.

Seamless Roaming:

  • Clients are anchored to a single controller (cluster member) regardless of roaming status or connected AP.
  • The roaming experience should be seamless – their L2/L3 information and sessions remain on the same mobility controller.

Client stateful failover

  • There is full redundancy within the cluster.
  • In the event of a cluster member failure, connected clients are failed over to the redundant cluster member.
  • There is zero disruption to wireless connectivity.

Client load balancing

  • Clients are automatically load-balanced within the cluster.
  • Clients are moved among cluster numbers in a stateful manner, which prevents disruption of services.

AP load balancing

  • As of AOS 8.1, APs automatically load-balanced across cluster members.

Items to remember

  • The mobility conductor provides centralized management, configuration, and control of the environment.
  • The cluster feature requires a mobility conductor-based deployment.
  • There is no license required to use the clustering feature.
  • APs do NOT terminate on the mobility conductor, nor does the mobility conductor service wireless clients.
  • The fact that the mobility conductor CANNOT be a cluster member does not reduce the effectiveness of the cluster solution.
  • Standalone controllers CANNOT be clustered.

Cluster Support

Cluster 1 – 70xx – Same OS version max 4 MD clusterCluster 2 – 72xx Same OS version Max 12 MD clusterCluster 3 – VMC Same OS version Max 4 VMC cluster

Additional cluster deployment considerations

  • All cluster members must run the same ArubaOS version (8.0 and higher)
  • A mix of 72xx and 70xx MDs in the same cluster is NOT recommended. If MDs are mixed, the maximum number of cluster members is reduced to four.
  • When the cluster terminates RAPs, max cluster members are reduced to four.
  • The cluster feature and the high availability and AP fast failover are mutually exclusive.

The 2019 clustering configuration post can be found here

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