Avaya S8700 Maintenance Manual page 1544

Maintenance-Object Repair Procedures
PN Warm Restarts
PN Warm Restart (PN Reset Level 1) is generally performed on an PN when the
recovery of that PN can be accomplished in less than 30 seconds. When
possible, Warm Restart minimizes the work required to reinitialize an PN, and
reduces the impact of an PN failure by avoiding the longer and highly destructive
PN Cold Restart. The primary cause of PN restarts is failure of the link from the
media server to the PN due to a hardware fault in the link's path. For most
hardware failures, this link (and thus the PN) cannot be recovered until the failed
hardware is replaced. However, several failures modes provide hardware
redundancy allowing the link to be recovered quickly. For instance (in a duplex-,
high-, or critical-reliability system), the failure of a Packet Interface circuit pack
causes a media server interchange that allows the link to be recovered quickly
over the newly active Packet Interface. Or on a Center Stage Switch (with
multiple fibers interconnecting the switch nodes), a link carried on one fiber can be
rerouted over another fiber.
If the EAL is recovered quickly, the PN Warm Restart returns the PN to service
with minimal effects on user service. If the EAL cannot be recovered quickly, the
PN is taken out of service and an PN Reset Level 2 (PN Cold Restart) is required
to return it to service.
PN Cold Restarts
If the PN-to-PN link has failed and has not been recovered within 30 seconds, the
PN is taken out of service and can be brought back into service only with an PN
Reset Level 2 (PN Cold Restart). Effects of an PN Cold Restart include a reset of
every circuit pack in the PN and the disconnection of every call to or from the PN.
Calls with both endpoints within the PN are dropped upon recovery.
PN Restart Escalation
PN restarts follow an escalation strategy controlled by maintenance software.
Whenever a request for an PN Reset Level 1 (PN Warm Restart) is made,
software checks to see if the restart should be escalated to an PN Reset Level 2
(PN Cold Restart). If any of the following are true, the restart is escalated:
At least two level 1 restarts have occurred and less than two hours has
elapsed since the last occurrence.
Current PN conditions do not allow a level 1 restart, such as when the PN
is out of service.
Less than 3 minutes has elapsed since the last PN Cold Restart, indicating
that the PN is unstable.
If two PN Cold Restarts have been executed in less than an hour and the link is
functional, but the PN has not recovered to an in-service state, a MAJOR alarm is
raised against EXP-PN, and the PN is put into Emergency Transfer by system
software. (Software can invoke PN Emergency Transfer only when the link to the
PN is up. If the link is down, the hardware automatically invokes Emergency
Transfer 1 minute after it detects a link failure).
8-822 Issue 1 May 2002 555-233-143