Alcatel-Lucent 9500 MXC User Manual page 176

Chapter 3. 9500 MXC Nodes
Double Break Operation
Vol. II-3-82
Typical Ring Delay Times
Table 3-29.
Ring Capacity
Delay Per Hop
Delay for 16 Hops
In the event there are two or more link failures on the ring, (adjacent, or
non-adjacent links), the traffic will wrap up to each side of the failed points to
provide limited service restoration. The node or nodes between the break points
will be isolated, but where there is an 'sub-ring' of isolated nodes (two or more
hops), traffic will wrap up to their node break points in the same way, to provide
normal service on all circuits that have been configured between them. Refer to
Figure 3-49.
Double-break Operation
Figure 3-49.
Node G
Node F
Sub-ring A
Circuits wrapped at nodes A and E
All circuits configured between
nodes A and E are maintained
All circuits configured to/from
other nodes on the ring are lost
20xE1 40xE1
0.45 ms 0.3 ms
7.2 ms 4.8 ms
Node A
Sub-ring A
Sub-ring B
Node E
Break
Node D
75xE1
0.25 ms
4 ms
Break
Node B
Node C
Sub-ring B
Circuits wrapped at nodes B and D
All circuits configured between
nodes B and D are maintained
All circuits configured to/from
other nodes on the ring are lost
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