MRP rings with shared interfaces (MRP Phase 2)

With MRP Phase 2, MRP rings can be configured to share the same interfaces as long as the interfaces belong to the same VLAN. Figure 1 shows examples of multiple MRP rings that share the same interface.

Figure 1. Examples of multiple rings sharing the same interface - MRP Phase 2

On each node that will participate in the ring, you specify the ring ID and the interfaces that will be used for ring traffic. In a multiple ring configuration, a ring ID determines its priority. The lower the ring ID, the higher priority of a ring.

A ring ID is also used to identify the interfaces that belong to a ring.

Figure 2. Interface IDs and types

For example, in Figure 2, the ID of all interfaces on all nodes on Ring 1 is 1 and all interfaces on all nodes on Ring 2 is 2. Port 1/1/1 on node S1 and Port 1/2/2 on S2 have the IDs of 1 and 2 since the interfaces are shared by Rings 1 and 2.

The ring ID is also used to determine an interface priority. Generally, a ring ID is also the ring priority and the priority of all interfaces on that ring. However, if the interface is shared by two or more rings, then the highest priority (lowest ID) becomes the priority of the interface. For example, in Figure 2, all interfaces on Ring 1, except for Port 1/1/1 on node S1 and Port 1/2/2 on node S2 have a priority of 1. Likewise, all interfaces on Ring 2, except for Port 1/1/1 on node S1 and Port 1/2/2 on node S2 have a priority of 2. Port 1/1/1 on S1 and Port 1/2/2 on S2 have a priority of 1 since 1 is the highest priority (lowest ID) of the rings that share the interface.

If a node has interfaces that have different IDs, the interfaces that belong to the ring with the highest priority become regular ports. Those interfaces that do not belong to the ring with the highest priority become tunnel ports. In Figure 2, nodes S1 and S2 have interfaces that belong to Rings 1 and 2. Those interfaces with a priority of 1 are regular ports. The interfaces with a priority of 2 are the tunnel ports since they belong to Ring 2, which has a lower priority than Ring 1.