Avaya Definity SI, Maintenance Manual, Page: 2048 / 2968

Maintenance Object Repair Procedures
555-233-123 10-1262 Issue 4 May 2002
The interactions between the Packet Bus and the circuit packs that use the bus
are complex. For this reason, the Packet Bus can be alarmed due to a circuit pack
failure and, conversely, circuit packs can be alarmed due to a Packet Bus failure.
This section on PKT-BUS is limited to a description of the Error and Alarm Log
entries for the Packet Bus maintenance object and to a description of the Packet
Bus test sequence.
NOTE:
Refer to Chapter 9, ‘‘Packet Bus Fault Isolation and Correction’’ for a
complete discussion of Packet Bus maintenance and also the interactions of
the bus with the Packet circuit packs. The chapter discusses fault isolation
and correction procedures, and it should be referenced for all procedures
and required decisions. The “Packet Bus Fault Isolation Flowchart” section
of the chapter is the normal starting point for experienced technicians;
however, technicians who are unfamiliar with the Packet Bus and its use
should refer to the introductory material.
A failure of one or more circuit packs that use the Packet Bus can cause a Packet
Bus alarm. In addition, a Packet Bus failure can cause loss of service to one or
more such circuit packs, as well as to the ports and endpoints associated with the
ISDN-BRI circuit pack (BRI-PORT, ABRI-PORT, BRI-SET, BRI-DAT, and
ASAI-ADJ). These interactions are discussed in the “Circuit Packs That Use the
Packet Bus” section of the chapter referenced in the note above.
The following list summarizes some of the important points to consider when
working with the Packet Bus.
■
The Maintenance/Test circuit pack (TN771) is a critical tool for isolating
Packet Bus faults. This circuit pack is present in each port network of a
critical reliability system that is using the Packet Bus. In high availability
and standard systems, the circuit pack may be included as a customer
option. If a TN771 is not present, one must be taken to the customer site
to allow for proper fault isolation. (A determination as to whether a TN771
circuit pack is in the system is made by entering the list configuration
command.) Use of the Maintenance/Test Packet Bus port facilities is
described under “The Maintenance/Test Circuit Pack (TN771)” in the above
referenced chapter. Also, in the same chapter, the section entitled “Special
Precautions Concerning the TN771” describes other circumstances when a
TN771 must be taken to the customer site.
■
Certain catastrophic failures of a Packet Bus can cause all the Packet
circuit packs on that bus to report errors, thus generating a high volume of
maintenance activity for maintenance objects that are healthy. In order to
reduce this unnecessary activity, some maintenance for Packet circuit
packs, ports, and endpoints is curtailed or disabled when such a
catastrophic Packet Bus failure is suspected. The following list summarizes
the error-logging and testing impact of this strategy: