LevelOne GEL-5261, User Manual

Page: 425 / 570

Chapter 13
| Basic Administration Protocols
Ethernet Ring Protection Switching
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This is enough time to allow a reporting ring node to transmit two R-APS
messages and allow the ring to identify the latent condition.
This delay timer is activated on the RPL owner node. When the relevant delay
timer expires, the RPL owner node initiates the reversion process by
transmitting an R-APS (NR, RB) message. The delay timer, (i.e., WTR or WTB) is
deactivated when any higher priority request preempts this delay timer.
The delay timers (i.e. WTR and WTB) may be started and stopped by the system.
A request to start running the delay timer does not restart the delay timer. A
request to stop the delay timer stops the delay timer and resets its value. The
Clear command (Configure Operation page) can be used to stop the delay
timer.
◆
WTR Timer – The wait-to-restore timer is used to verify that the ring has
stabilized before blocking the RPL after recovery from a signal failure.
(Range: 5-12 minutes)
If the switch goes into ring protection state due to a signal failure, after the
failure condition is cleared, the RPL owner will start the wait-to-restore timer
and wait until it expires to verify that the ring has stabilized before blocking the
RPL and returning to the Idle (normal operating) state.
◆ WTB Expire – The time before the wait-to-block timer expires.
◆ WTR Expire – The time before the wait-to-restore timer expires.
◆ West / East – Connects to next ring node to the west/east.
Each node must be connected to two neighbors on the ring. For convenience,
the ports connected are referred to as east and west ports. Alternatively, the
closest neighbor to the east should be the next node in the ring in a clockwise
direction, and the closest neighbor to the west should be the next node in the
ring in a counter-clockwise direction.
◆
Interface – The port or trunk attached to the west or east ring port.
Note that a ring port cannot be configured as a member of a spanning tree, a
dynamic trunk, or a static trunk.
◆
Port State – Once configured, this field shows the operational state of the ring
ports for this node:
■
Blocking – The transmission and reception of traffic is blocked and the
forwarding of R-APS messages is blocked, but the transmission of locally
generated R-APS messages is allowed and the reception of all R-APS
messages is allowed.
■
Forwarding – The transmission and reception of traffic is allowed;
transmission, reception and forwarding of R-APS messages is allowed.
■
Unknown – The interface is not in a known state.
◆ Local SF – Shows if a signal fault exists on a link to the local node.