Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 557)

Multi-Service IronWare Switching Configuration Guide 527
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Dual-end blocking
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Double Forced Switch
A local FS is of a higher priority than a received R-APS (FS); therefore, the local FS request blocks
the port even when the node receives a R-APS(FS) from another FS request of another node.
After the first FS clears, the node starts the guard timer and sends out a R-APS (NR). The adjacent
nodes of the first cleared FS node will not process or forward the R-APS (NR) because they are still
receiving R-APS (FS) from the second FS node. When the first FS node receives R-APS (FS) from the
second FS nodes, it unblocks any blocked port and stops transmitting any lower priority R-APS
messages. At this point, the topology follows the single FS process, as previously described.
Dual-end blocking
Dual-end blocking is a user configurable feature to directly conserve bandwidth of the RPL and
indirectly conserve processing power of the RPL owner. When you configure a node in a major ring
adjacent to the RPL owner to be an RPL node with dual-end blocking enabled, data traffic and
R-APS messages will not be forwarded to the blocked port of the RPL owner.
When a failure occurs in the ring and the RPL node (not the RPL owner) receives a R-APS (of type
SF, FS, or MS), the RPL node unblocks the configured dual-end blocked port. When the RPL node
receives a R-APS (NR, RB), it reblocks the originally configured dual-end blocked port. To configure
dual-end blocking you need to configure the RPL and dual-end blocking on both the RPL owner and
the adjacent peer (RPL node).
Non-revertive mode
In non-revertive mode, the traffic channel is allowed to use the RPL, if it is not failed, after a switch
condition clears. In the recovery from a Protection state, the RPL owner generates no response
regarding the reception of NR messages. When other healthy nodes receive the NR message, there
is no action in response to the message. After the operator issues a no command for non-revertive
mode at the RPL owner, the non-revertive operation is cleared, WTB or WTR timer starts, as
appropriate, and the RPL owner blocks its port to the RPL and transmits a R-APS (NR, RB)
message. Upon receiving the R-APS (NR, RB), any blocking node should unblock its non-failed port.
Interconnected rings
Interconnected Rings consist of one major ring and one or more sub-rings with shared physical
links. The ring links between the interconnection nodes are controlled and protected by the ERP
ring to which they belong. A sub-ring is similar to the major ring in that each sub-ring has an RPL
and an RPL owner. The RPL owner can be configured in any node belonging to the ring.
The dotted lines in Figure 143 show two of the many potential sub-rings that you can configure.
FIGURE 143 Interconnected rings with major and sub rings shown