Supermicro SSE-G2252, User Manual

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Chapter 35: ERPS Commands
– 1060 –
initiates a guard timer. When another recovered ring node (or nodes)
holding the link block receives this message, it compares the Node ID
information with its own Node ID. If the received R-APS (NR) message
has the higher priority, this ring node unblocks its ring ports.
Otherwise, the block remains unchanged. As a result, there is only one
link with one end blocked.
The ring nodes stop transmitting R-APS (NR) messages when they
accept an R-APS (NR, RB – RPL Blocked), or when another higher
priority request is received.
•
Recovery with Revertive Mode – When all ring links and ring nodes
have recovered and no external requests are active, reversion is
handled in the following way:
a.
The reception of an R-APS (NR) message causes the RPL Owner
Node to start the WTR (Wait-to-Restore) timer.
b.
The WTR timer is cancelled if during the WTR period a higher
priority request than NR is accepted by the RPL Owner Node or is
declared locally at the RPL Owner Node.
c.
When the WTR timer expires, without the presence of any other
higher priority request, the RPL Owner Node initiates reversion by
blocking its traffic channel over the RPL, transmitting an R-APS (NR,
RB) message over both ring ports, informing the ring that the RPL is
blocked, and performing a flush FDB action.
d.
The acceptance of the R-APS (NR, RB) message causes all ring
nodes to unblock any blocked non-RPL link that does not have an SF
condition. If it is an R-APS (NR, RB) message without a DNF (do not
flush) indication, all ring nodes flush the FDB.
•
Recovery with Non-revertive Mode – In non-revertive operation, the
ring does not automatically revert when all ring links and ring nodes
have recovered and no external requests are active. Non-revertive
operation is handled in the following way:
a.
The RPL Owner Node does not generate a response on reception of
an R-APS (NR) messages.
b.
When other healthy ring nodes receive the NR (Node ID) message,
no action is taken in response to the message.
c.
When the operator issues the erps clear command for non-revertive
mode at the RPL Owner Node, the non-revertive operation is
cleared, the RPL Owner Node blocks its RPL port, and transmits an
R-APS (NR, RB) message in both directions, repeatedly.
d.
Upon receiving an R-APS (NR, RB) message, any blocking node
should unblock its non-failed ring port. If it is an R-APS (NR, RB)
message without a DNF indication, all ring nodes flush the FDB.
•
Recovery for Forced Switching – An erps forced-switch command is
removed by issuing the erps clear command to the same ring node