414 BigIron RX Series Configuration Guide53-1002253-01Ring initialization for shared interfaces14Ring initialization for shared interfacesFIGURE 72 Interface IDs and typesFor example, in Figure 72, the ID of all interfaces on all nodes on Ring 1 is 1 and all interfaces onall nodes on Ring 2 is 2. Port 1/1 on node S1 and Port 2/2 on S2 have the IDs of 1 and 2 since theinterfaces are shared by Rings 1 and 2.The ring’s ID is also used to determine an interface’s priority. Generally, a ring’s ID is also the ring’spriority and the priority of all interfaces on that ring. However, if the interface is shared by two ormore rings, then the highest priority (lowest ID) becomes the priority of the interface. For example,in Figure 72, all interfaces on Ring 1, except for Port 1/1 on node S1 and Port 2/2 on node S2 havea priority of 1. Likewise, all interfaces on Ring 2, except for Port 1/1 on node S1 and Port 2/2 onnode S2 have a priority of 2. Port 1/1 on S1 and Port 2/2 on S2 have a priority of 1 since 1 is thehighest 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 thehighest priority become regular ports. Those interfaces that do not belong to the ring with thehighest priority become tunnel ports. In Figure 72, nodes S1 and S2 have interfaces that belong toRings 1 and 2. Those interfaces with a priority of 1 are regular ports. The interfaces with a priorityof 2 are the tunnel ports since they belong to Ring 2, which has a lower priority than Ring 1.How ring breaks are detected and healed betweenshared interfacesIf the link between shared interfaces breaks, the secondary interface on Ring 1’s master nodechanges to a preforwarding state. The RHP packet sent by port 3/1 on Ring 2 is forwarded throughthe interfaces on S4, then to S2. The packet is then forwarded through S2 to S3, but not from S2 toS1 since the link between the two nodes is not available. When the packet reaches Ring 1’s masterRing 1 Ring 2S1S211111 1 11 TT 2 2 2222221,21,2 port1/1port2/2C = customer port
