Nortel SONET AccessNode Manual page 56

2-38 DS3 tests, STS-1 tests, and optical in-bay tests
Procedure 2-4 (continued)
Testing DS3 or STS-1 protection switching
Step
Testing automatic switching due to failure of a DS3/STS mapper or STS-1
interface card
23
24
25
26
Testing forced switching (and automatic switching override)
AccessNode Vol 3B 323-3001-221 Issue 2.0
Action
Wearing antistatic wrist protection, to simulate a circuit pack failure, remove
the first working DS3/STS mapper or STS-1 interface card from its backplane
connector.
The appropriate protection screen displays an asterisk (*) in the AutoSw field
of the G1 circuit pack group. This indicates that the protection mapper has
taken over for the disconnected circuit pack.
Note: The DS3s/STS-1s that are normally handled by the failed mapper (that
is, the disconnected mapper) continue to enter and exit the
common-equipment shelf by way of BNC I/O cards associated with that
mapper. The traffic is rerouted to the protection mapper by way of the DS3 or
STS-1 protection bus. This is in the backplane of the shelf.
Press the Start/Stop button twice to reset the error count to zero.
The DS3/STS-1 test set indicates in process and displays 0 bit error.
To verify that DS3 or STS-1 continuity is maintained, press the Single Bit Error
Inject button three times.
The DS3/STS-1 test set indicates 3 bit errors received.
The next activity depends on the number of working DS3/STS mappers or
STS-1 interface cards that are installed.
If you have
one working DS3/STS mapper or STS-1 interface card
two or more working DS3/STS mappers or STS-1
interface cards
Note: Two working DS3/STS mappers or STS-1 interface cards are required
to test forced switching as described below. For simplicity in this procedure,
the second working mapper is assumed to be G2. When entering commands,
enter the group number of a second working DS3/STS mapper or STS-1
interface card in your shelf. For the group numbers associated with DS3/STS
mappers or STS-1 interface cards, see Table 2-1 on page 2-3.
—continued—
Then go to
step 60
step 27