LevelOne GTL-2691 User Manual
Page 470
C
HAPTER
14
| Basic Administration Protocols
Ethernet Ring Protection Switching
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RPL Owner – Configures a ring node to be the Ring Protection Link
(RPL) owner.
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Holdoff Timer – The hold-off timer is used to filter out intermittent
link faults. Faults will only be reported to the ring protection mechanism
if this timer expires. (Range: 0-10000 milliseconds, in steps of 100
milliseconds)
In order to coordinate timing of protection switches at multiple layers, a
hold-off timer may be required. Its purpose is to allow, for example, a
server layer protection switch to have a chance to fix the problem
before switching at a client layer.
When a new defect or more severe defect occurs (new Signal Failure),
this event will not be reported immediately to the protection switching
mechanism if the provisioned hold-off timer value is non-zero. Instead,
the hold-off timer will be started. When the timer expires, whether a
defect still exists or not, the timer will be checked. If one does exist,
that defect will be reported to the protection switching mechanism. The
reported defect need not be the same one that started the timer.
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Guard Timer – The guard timer is used to prevent ring nodes from
receiving outdated R-APS messages. During the duration of the guard
timer, all received R-APS messages are ignored by the ring protection
control process, giving time for old messages still circulating on the ring
to expire. (Range: 10-2000 milliseconds, in steps of 10 milliseconds)
The guard timer duration should be greater than the maximum
expected forwarding delay for an R-APS message to pass around the
ring. A side-effect of the guard timer is that during its duration, a node
will be unaware of new or existing ring requests transmitted from other
nodes.
◆
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.
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Control VLAN – A dedicated VLAN used for sending and receiving E-
APS protocol messages. (Range: 1-4094)
Configure one control VLAN for each ERPS ring. First create the VLAN to
be used as the control VLAN (see
), add the ring ports for the east and west interface as tagged
members to this VLAN (see
"Adding Static Members to VLANs" on
), and then use this parameter to add it to the ring.
The Control VLAN must not be configured as a Layer 3 interface (with
an IP address), a dynamic VLAN (with GVRP enabled), nor as a private
VLAN. In addition, only ring ports may be added to the Control VLAN.
No other ports can be members of this VLAN. Also, the ring ports of the