Alcatel-Lucent 9500 MXC, User Manual, Page: 655 / 916

9500 MXC User Manual
3DB 23063 ADAA - Rev 004 July 2007 Vol. V-1-17
commands to set the required online combination before commencing the tests.
NCC/NPC
The NPC provides redundancy for NCC TDM bus clock and power supply
functions.
• For an NCC bus clock failure the NPC provides protection for tributary and
auxiliary traffic; alarm I/O is not protected.
• Protection switching is not hitless for a TDM bus clock failure. The restoration
time is 100 ms maximum, during which time all traffic on the node is affected.
• Protection is hitless for a power supply failure. If the NCC converter or one of
its supply rails fails, the NPC takes over without interruption. And vice versa.
(The NPC provides secondary power rails; there is no
switching backwards and
forwards).
When the TDM bus clock has switched to NPC control, it does not automatically
revert to NCC control on restoration of the NCC. Return to NCC control requires
either withdrawal/failure of the NPC, or use of diagnostic commands in the
System/Controls screen.
NCC/NPC Protection Test Procedure
This procedure uses the built-in BER tester or an industry-standard hand-held
tester that provides a one-second error count resolution. Refer to Test
Measurement on page 1-7.
1. Set a BER test on a trib with a local or remote loopback. Confirm zero errors.
2. Ensure the NPC Status LED is green and its Protect LED is unlit.
3. Disconnect the NCC -48 Vdc supply connector and confirm a count of one
errored second (or possibly two errored seconds). The NPC Protect LED is
green, indicating the bus clock has switched to NPC control.
4. Withdraw the NCC from its backplane and confirm no further errors.
Manual control of bus clock switching allows customer selection of a time when it
least impacts traffic. There is no operational need to always revert to NCC for bus
clocking.
If bus clocking is with the NPC, then the NCC can be removed and restored
without impacting traffic. If the clock is with the NCC, the NPC can be removed
and restored without impact.
As soon as power to the NCC is disconnected, CT communication is lost and
screens will be frozen as at the time of loss. Normal communication will not return
until power is restored and the NCC has completed internal status checks, which
typically requires up to two minutes.