PKT-BUS (Packet Bus)
Issue 5 October 2002
1455
555-233-119
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.
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The Maintenance/Test circuit pack (TN771) is a critical tool for isolating
Packet Bus faults. The circuit pack is optional, and is not present in all
systems. 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.
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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:
c. In-line errors indicating possible Packet Bus failures are placed into
the error log, but are not acted upon. Circuit pack maintenance
objects thus affected include:
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BRI-BD
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LGATE-BD
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ASAI-BD
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TBRI-BD
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PGATE-BD
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CLAN-BD
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UDS1-BD
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MAPD-BD
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MEDPRO