The following considerations apply to default QinQ SAPs for transit service in a ring deployment configurations:
If an Epipe service is used with default QinQ SAPs on the ring ports for transit service in a ring deployment, no protection mechanism is available for the transit service (that is, Epipe service with the default QinQ SAPs on ring ports). Both Epipe and VPLS services that are originating on different nodes in the ring can use the transit service.
Protection and loop-detection mechanisms can be implemented for VPLS service configured in the ring nodes, by using MVPLS with xSTP on the nodes where the VPLS service is configured. No protection mechanisms are available for use with Epipe services on the node that originates the service.
If a VPLS service is used with default QinQ SAPs on the ring ports for transit service in a ring deployment, either MVPLS/xSTP or G.8032 can be used to protect the transit service (that is, VPLS service with the default QinQ SAPs on ring ports). In this case, VPLS services that are originating on different nodes in the ring and use the transit VPLS service are also protected. Epipe services that are originating on different nodes in the ring cannot use the transit VPLS service.
When using VPLS service with default QinQ SAPs for transit service with either G.8032 or MVPLS with xSTP configured for protection, load-balancing of the traffic based on the VLAN IDs is not possible. If load-balancing is needed, it is better to use Epipe service with default QinQ SAPs as the transit service.