User manual

Product Description
Controller and DS3 Redundancy
2-20 July 2004 Wide Bank 28 DS3 - Release 2.4
The Wide Bank switching performance complies with Telcordia TR-TSY-752, paragraph 8.4, sub-
paragraph 1, which states that no more than 10 bit errors are caused by the switching operation, and
also that the switching operation is accomplished within 250 ns.
The threshold at which DS3 switching takes place is determined by an LCV count within a certain
length of time. This threshold can be set for different values using the DS3 threshold command,
which is explained in detail in DS3 in Chapter 8. For a definition of LCVs, see Line Code Violations
and Bipolar Violations on page 2-15.
NOTE: After a power cycle or switching event, switching cannot occur again until the
original Controller and DS3 line have experienced five minutes of error-free operation. The
five-minute delay is built-in, and conforms to standards to prevent oscillation during poor
DS3 line conditions.
Operator-Initiated Switch
A switch of Controllers can be initiated manually by using the switch command. At the prompt,
enter the switch command:
(A: Active)> switch
If the secondary Controller is fully functional, the switch is initiated immediately.
If the secondary Controller is considered non-functional by the processor, a prompt will ask to
continue. If the choice is to continue with the switch, the switch is initiated unless the secondary
Controller is experiencing catastrophic failure, in which case the switch is aborted. If revertive
switching is enabled in network protection mode, the switch will last only five minutes. The Wide
Bank will then switch back to the original state if the originally active path is error-free.
Restoring to Original Status (Revertive Switching)
Once a switch has occurred, another switch back to the original status (revertive switching) can
sometimes occur, depending on certain configurations and equipment status, described below.
Revertive Switching with Electronics Protection
When using electronics protection (two Controller cards and one DS3 line), a switch to the
standby Controller card cannot revert automatically. After five minutes automatic protection
switching is rearmed, allowing another switch if subsequent errors occur. Without errors, a
switch back to the originally active Controller card must be initiated using a switch command.
Revertive Switching with Electronics and Network Protection
When using network protection (two Controller cards and two DS3 lines), switching can be
configured so that it can automatically revert to original state (after five minutes of error-free
operation on the original Controller). Then the original Controller and the original DS3 line
again carry the traffic. To configure revertive switching, set revertive ds3 on and arm on.