Avaya MCC1 Maintenance Procedures page 263

The following paragraphs supplement the corresponding letter in the flowchart.
a Problems with the system clock (TDM-CLK) can cause service disruptions on the Packet Bus as
well as on the TDM Bus. Therefore, if there are alarms active against TDM-CLK, these alarms
should be resolved before any other Packet Bus fault isolation is attempted.
NOTE:
All TDM-CLK problems should be resolved before the process is continued, even if the
problems refer only to the TDM Bus. (This is an exception to the previous note.) This is
recommended because a Packet Bus problem cannot cause a TDM-CLK problem, while a
TDM-CLK problem can cause a Packet Bus problem.
b The question ''Are the Packet Bus problems resolved?'' appears several times on the flowchart.
This is a general question that can involve several checks. The basic question is ''Are the
problems that caused you to use this flowchart resolved?'' Some of the more specific questions
might be:
• Are all Packet Bus alarms resolved?
• Are all Packet circuit pack (port, endpoint) alarms resolved?
NOTE:
If all alarms are resolved, issue the clear pkt command. This command attempts to put
the switch back into the service state by resolving any BRI problems that exist. Refer to
the Maintenance Commands Reference (555-245-101) for more information.
• Are all ISDN-BRI stations/data modules and/or ASAI adjuncts in service?
• Does the Maintenance/Test Packet Bus port (in normal or standalone mode) still indicate a
Packet Bus fault?
c If only a single EPN is affected, the Packet Control is probably not the source of the problem.
However, if all of the ISDN-BRI circuit packs are located in a single EPN, assume that the answer
to this question is ''No,'' and check the Packet Control.
d A Packet problem that affects more than one port network is probably caused by either a Packet
Control failure or a PPN Packet Bus failure. The Packet Control is checked before the Packet Bus
Fault Correction procedures are implemented.
e Because the Packet Bus in each port network is physically separate, each affected port network
must be checked individually. The PPN should be checked first, however, since any EPN Packet
problems are usually resolved once the PPN Packet problem is resolved. After resolving the
problem in one port network, be sure to check if the problems in other port networks have also
been resolved.
f This step applies only when an attempt to resolve an EPN Packet Bus problem is made. When
checking the Expansion Interfaces in an EPN, be sure to check the corresponding ones in the
PPN. Also, recall that all Expansion Interfaces in 286 systems, 386 systems, or later systems that
are using the Packet Bus must be TN570s. Using TN776s results in an EPN where TDM traffic
works but Packet traffic does not work.
g If a TN771 is not present, one must be installed to accommodate the standalone mode, which is
discussed earlier in this chapter.
h If a TN771 is present, it can fail in such a fashion that it eventually disrupts the Packet Bus or
misinterprets a Packet Bus problem.
i If work is being done on-site, follow the procedures described
work is not being done on-site, go to the next step.
Maintenance Procedures
December 2003
Packet and serial bus maintenance
S8100 packet bus fault isolation and repair
Standalone mode on page 253. If
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