Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 558)

528 Multi-Service IronWare Switching Configuration Guide
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Interconnected rings
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When a sub-ring initializes, each ERN in the non-closed ERP sends out a R-APS (NR). After the RPL
owner receives a R-APS (NR), it blocks the RPL; and the RPL owner sends out a R-APS (NR, RB). The
shared link remains blocked even if the shared link has a SF error. The blocking state in ERP means
the R-APS channel is blocked at the same port where the traffic channel is blocked, except on
sub-rings without use of R-APS virtual channel.
Virtual channel support is not available in release 5.1.0. A sub-ring in segments interconnecting
major rings is not supported.
Figure 144 shows a major ring and two segments not supported as a
sub-ring.
Blocking prevents R-APS messages received at one ring port from being forwarded to the other ring
port; it does not prevent the R-APS messages locally generated at the ERP control process from
being transmitted over both ring ports, and it also allows R-APS messages received at each port to
be delivered to the ERP control process.
Each ERN in a major ring terminates R-APS messages received on a blocking port and does not
forward the message if the port is in a blocking state. Each ERN in a sub-ring, however, still
forwards the R-APS messages received on a blocking port.
FIGURE 144 Unsupported sub-ring in segments