Ethernet ring protection switching offers ITU-T G.8032 specification compliance to achieve resiliency for Ethernet Layer 2 networks. Similar to G.8031 linear protection (also called Automatic Protection Switching (APS)), G.8032 (Ethernet-ring) is built on Ethernet OAM and often referred to as Ring Automatic Protection Switching (R-APS).
Ethernet-rings are supported on VPLS SAPs (VPLS, I-VPLS, B-VPLS). VPLS services supporting Rings SAPs can connect to other rings and Ethernet service using VPLS and R-VPLS SAPs. Ethernet-rings enables rings for core network or access network resiliency. A single point of interconnection to other services is supported. The Ethernet-ring service is a VLAN service providing protection for ring topologies and the ability to interact with other protection mechanisms for overall service protection. This ensures failures detected by Ethernet-ring only result in R-APS switchover when the lower layer cannot recover and that higher layers are isolated from the failure.
Rings are preferred in data networks where the native connectivity is laid out in a ring or there is a requirement for simple resilient LAN services. Because of the symmetry and the simple topology, rings are viewed a good solution for access and core networks where resilient LANs are required. The SR OS implementation can be used for interconnecting access rings and to provide traffic engineered backbone rings.
Ethernet-rings use one VID per control per ring instance and use one (typically) or multiple VIDs for data instances per control instance. A dedicated control VLAN (ERP VLAN) is used to run the protocol on the control VID. G.8032 controls the active state for the data VLANs (ring data instances) associated with a control instance. Multiple control instances allow logically separate rings on the same topology.
The SR OS implementation supports DOT1q, QinQ and PBB encapsulation for data ring instances. The control channel supports dot1q and QinQ encapsulation. The control channel can support DOT1Q while the data channels use queuing if the global config>system>ethernet>new-qinq-untagged-sap command is enabled.