Dell N3200-ON EMC Networking N-Series Switches User Guide version 6.6.3 - Page 1035

Ethernet Ring Protection Switching Port Role Ethernet Ring Protection Switching (ERPS) defines three port roles: the RPL owner port, the RPL neighbor port, and the Normal port. Under normal conditions, the RPL is blocked (not used for data traffic), thus preventing loops. The ports at each end of the RPL are called RPL owner and RPL neighbor. RPL Owner Port It is the RPL owner that provides the main control for protection switching. The owner generates R-APS No Request RPL-Blocked (NR, RB) messages continuously and is in charge of the RPL's blocking and forwarding states. Under normal operation, when there are no failures, the RPL owner generates R-APS (NR, RB) messages. It periodically sends these, every five seconds, over both of its ring ports. These messages indicate which of its ring ports is being blocked. RPL Neighbor Port The port adjacent to the RPL owner is the RPL neighbor port. Both the RPL owner port and the RPL neighbor ports are blocked in normal situations to prevent loops. Under the Signal Fail condition, both the RPL owner and neighbor ports are unblocked. Configuration of a RPL neighbor port is optional. Normal Port A normal port monitors the status of the directly connected ring link and sends R-APS PDUs to notify the other ports of its link status changes. R-APS Channel R-APS messages require a separate ring-wide VLAN known as the R-APS VLAN or R-APS Channel. Each ERP instance uses an R-APS VLAN for sending and receiving R-APS messages. The function of the R-APS VLAN is to support a path for monitoring the ring and maintaining its operational functions. R-APS VLAN must have all ERP ring ports as members. Nodes receiving the R-APS message must send a copy Ethernet Ring Protection 1035