9500 MXC User Manual
3DB 23063 ADAA - Rev 004 July 2007 Vol. II-3-81
Figure 3-48. Ring-break Operation
Providing the ring only experiences a single fault, all traffic is deliverable once
the ring has completed the wrapping operation.
When wrapped, the ring is left unprotected against a further failure. For this
reason, when the condition(s) that caused the wrap are removed, the ring reverts
to normal operation (restorative switching).
Ring wrapping and restoration is nor hitless. Refer to Ring Protection Switching
Criteria on page 3-98 for details.
Ring Delay Times
There is no practical limit on the number of hops in a ring providing the delay
times do not become an issue. The delay is a function of ring capacity and the
number of hops on the ring; the higher the capacity, the lower the delay for the
same number of hops. Refer to Table 3-29. To avoid most instances of
unacceptable delays for equipment connected to a 9500 MXC ring, the number of
hops should not exceed sixteen.
Tx
Tx
Tx
Tx Rx
Node A
Node C
Node D
Rx
Rx
Rx
Ring
break
Circuits wrapped
at Nodes C and D
Node B
Primary ring
Secondary ring
(in use)
The revertive switch command for return to normal service is initiated after the
relevant alarms on the failed link have been cleared for a period set by the
Error-Free Timer (default 5 minutes), or by the optional Delay Ring Unwrap Timer,
which sets a time of day for an unwrap. For more information refer to Unwrap
Timers on page 3-99.
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