UMN:CLI
User Manual
V8102
206
base of the switch all MAC entries that are forwarded to the ports. The Flushing of FDB is
always followed by a period with MAC learning disabled. To prevent wrong MAC learning
due to the remaining packets in the buffer, a node does not learn MAC addresses during
a configured guard time.
After RPL-owner node receives SF frames from other nodes, it unblocks its RPL port for
traffic transmission with Node B directly connected to the RPL port. RPL-owner node
sends NR-RB (No Request and RPL Blocked) frame and informs the other nodes that its
RPL port begins forwarding the traffic.
The following figure shows an example of R-APS operation in case of a link failure and a
ring protection.
Fig. 7.4
Ring Protection in case of Link Failure
If Node A and Node B detect the link failure being recovered, they send No Request (NR)
frames to RPL owner. But these nodes keep the blocking status of the link recovered
ports. After RPL owner receives the frames, it blocks its own west RPL port. The RPL
owner sends RPL Blocked frame that informs other nodes the blocking status of its RPL
port. By receiving the frame, the nodes unblocks the ring ports which are detected a Link
Failure recovery. The Ethernet ring is back to normal (Idle) state. RPL-owner node sends
NR-RB (No Request and RPL Blocked) frame in idle state.
The following figure
shows an example of a Link Failure and Ring Recovery operation.
Fig. 7.5
Ring Recovery Procedure
