This chapter applies only to the NetEngine 8000 F1A.
Figure 1 shows typical pseudo wire (PW) automatic protection switching (APS) networking. The network comprises an access ring and an aggregation ring. A BTS/NodeB is connected to a cell site gateway (CSG). A BSC/RNC is connected to an RSG. Primary and secondary PWs are established between a CSG and an RSG. The PWs can be either single-segment PWs (SS-PWs) or multi-segment PWs (MS-PWs). A BTS/NodeB communicates with a BSC/RNC through a mobile broadband (MBB) network.
PW APS is deployed on the bearer network to improve reliability. APS instances are configured on CSGs and RSGs, and the primary/secondary pseudo wire (PW) protection group is associated with each APS instance. APS instructs the source and destination ends to implement bidirectional protection switching in the same manner to achieve delayed switching and wait-to-restore (WTR) for PW protection.