Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 1015)

Brocade 6910 Ethernet Access Switch Configuration Guide 965
53-1002581-01
Ethernet Ring Protection Switching
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• MEG Level – The maintenance entity group (MEG) level which provides a communication
channel for ring automatic protection switching (R-APS) information. (Range: 0-7)
This parameter is used to ensure that received R-APS PDUs are directed for this ring. A unique
level should be configured for each local ring if there are many R-APS PDUs passing through
this switch.
• Node ID – A MAC address unique to the ring node. The MAC address must be specified in the
format xx-xx-xx-xx-xx-xx or xxxxxxxxxxxx.
• Node State – Refer to the parameters for the Show page.
• West Port – Connects to next ring node to the west.
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.
Once configured, this field shows the ring port for this node, and the interface state:
• 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.
• Down – The interface is not linked up.
• Unknown – The interface is not in a known state.
• East Port – Connects to next ring node to the east.
• RPL Port – If node is connected to the RPL, this shows by which interface.
• RPL Owner – Configures a ring node to be the Ring Protection Link (RPL) owner.
• 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.
• 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.