Avaya Definity SI Maintenance Manual page 1551

EXP-INTF (Expansion Interface Circuit Pack)
Relationship Between Expansion Interface and
Tone-Clock Circuit Packs
The Expansion Interface fiber link depends on the system clock that is provided
by the Active Tone-Clock circuit pack on each network. (See TDM-CLK and
TONE-BD Maintenance documentation.) Each Expansion Interface circuit pack
transmits over the fiber at a rate derived from the system clock on its network. If
the Active Tone-Clock is defective to the point where the system clock frequency it
produces is out of the specified range ("out of spec"), an Expansion Interface Link
might go down even though the Expansion Interface circuit packs are healthy. In a
High or Critical Reliability system, both links could go down if there is a defective
Active Tone-Clock.
Whether or not a link goes down, depends on certain characteristics of the
Expansion Interface circuit packs. An Expansion Interface circuit pack should not
be replaced if the link on which it resides goes down because of a defective Active
Tone-Clock circuit pack. The defective Tone-Clock circuit pack should be replaced
instead. The Expansion Interface circuit packs are more sensitive to a defective
system clock than the rest of the components of the system. Therefore, testing of
the Tone-Clock circuit pack might not reveal a problem.
The symptoms of the problem in which an invalid system clock causes an
Expansion Link to go down are as follows:
1. If the Active PPN Tone-Clock circuit pack is providing an invalid system
clock:
a. The EPN Expansion Interface circuit pack yellow LED blinks quickly.
b. The PPN Expansion Interface circuit pack yellow LED blinks slowly.
2. If the EPN Tone-Clock circuit pack is providing an invalid system clock:
a. The PPN Expansion Interface circuit pack yellow LED blinks quickly
b. The EPN Expansion Interface circuit pack yellow LED blinks slowly
555-233-123
(Fiber Out-of-Frame condition).
If the EPN is up, Test #238 fails on this Expansion Interface circuit
pack.
(In-frame, No Neighbor condition).
Test #237 fails on this Expansion Interface circuit pack, but Test
#238 passes.
(Fiber Out-of-Frame condition).
Test #238 fails on this Expansion Interface circuit pack.
(In-frame, No Neighbor condition).
If the EPN is in-service, Test #237 fails on this Expansion Interface
circuit pack, but Test #238 passes.
Issue 4 May 2002 10-765