Each MRA exists as a cluster that consists of two servers, active and standby. Both servers in a cluster share a Virtual IP Address (VIP) that points to whichever server is active.
A backup MRA cluster shares a common pool of MPE servers with a primary MPE cluster. All of the MPE servers in the pool of a given MRA cluster will have backup connections to the backup MRA cluster. An MRA cluster and its backup are considered a mated pair.
An associated MRA cluster is one that is not the backup MRA cluster, but exists as part of a Diameter Route. (See Configuring Diameter Realm Based Peer Routes for more information on associated MRA servers.)
An MRA cluster can simultaneously be a backup to one MRA cluster and an associate of another. However, an MRA cluster cannot use the same MRA cluster as both a backup and an associate. Figure 1 shows a valid configuration of four MRA clusters, in two mated pairs, and how each cluster views its relationships with the other three. The four MRA clusters form a mesh network.
