Manual Switch is similar to the Force Switch except that only one Manual Switch is allowed for an Ethernet ring. The processing of which node retains the Manual Switch is based on the priority table and the node state. However only one Manual Switch is retained at the end for the ring.
Clearing the Manual Switch is done similar to the Force Switch.
Virtual Channel for Sub-rings
While the standard describes how the sub-rings can function with a virtual channel, in this implementation sub-rings will function only with the presence of virtual channels.
The R-APS control channel is blocked, as is traffic on the blocked ports for the control traffic entering on one ring port and getting forwarded to the other ring port. However, locally generated or delivered control traffic on the blocked port is supported.
Traffic is always blocked for the protected VLANs on the blocked ports of the ring/sub-ring in a G.8032 network.
Signal Failure and Recovery
- An Ethernet ring node detecting an SF condition on one of its ring ports blocks the traffic channel and R-APS channel on the failed ring port.
- The Ethernet ring node detecting an SF condition transmits an R-APS message indicating SF on both ring ports. The R-APS (SF) message informs other Ethernet ring nodes of the SF condition. R-APS (SF) messages are continuously transmitted by the Ethernet ring node detecting the SF condition while this condition persists. (The Periodic timer determines the interval of sending the SF after the first three.) For sub-ring interconnection nodes, the R-APS (SF) message is transmitted on the R-APS channel of the Sub-Ring port.
- Assuming the Ethernet ring node was in an idle state before the SF condition occurred, upon detection of this SF condition the Ethernet ring node triggers a local FDB flush.
- An Ethernet ring node accepting an R-APS (SF) message unblocks any blocked ring port that does not have an SF condition. This action unblocks the traffic channel on the RPL.
- An Ethernet ring node accepting an R-APS (SF) message stops transmission of other R-APS messages.
- An Ethernet ring node accepting an R-APS (SF) message without a DNF indication performs a flush FDB.