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PKT-BUS (Packet Bus)
Issue 1 June 2005 1791
This section on the PKT-BUS MO is limited to a description of the Error and Alarm Log entries
and the test sequence for the packet bus. The following list summarizes some of the important
points to consider when working with the packet bus.
● The Maintenance/Test circuit pack (TN771D) is a critical tool for isolating packet bus faults.
This circuit pack resides in each port network of a critical-reliability system (duplicated
servers and PNC). If a TN771D is absent, one must be taken to the customer site to allow
for proper fault isolation. Isolating and repairing packet-bus faults
in Maintenance
Procedures (03-300192) describes the Packet Bus testing facilities of the TN771D and
when one must be taken to the customer site.
● Certain catastrophic packet-bus faults have an effect on maintenance software activities
relating to packet circuit packs, ports, and endpoints:
- Packet circuit pack (BRI-BD, UDS1-BD) in-line errors indicating possible Packet Bus test
failures are logged in the error log, but are not acted upon.
- Port-level (BRI-PORT, ABRI-PORT) in-line errors on Packet circuit packs which indicate
possible Packet Bus failures are not logged or acted upon.
- Circuit pack and port in-line errors that are not relevant to the Packet Bus, or that indicate
a circuit pack failure, are acted upon in the normal fashion.
- Periodic and scheduled background maintenance are not affected.
- Foreground maintenance (for example, a test board command executed at a
terminal) is not affected.
The actions in the previous list serve to reduce the system load, which could become
excessive if many MOs are affected by a packet bus failure. However, such an excessive
load should in no way impede the isolation and the correction of the faults.
When the above actions are implemented, Error Type 3329 is logged against PKT-BUS,
and a Warning alarm is raised. Other Packet Bus errors may raise more severe alarms,
thereby overriding the Warning alarm.
● S8700 MC: Since all packet traffic requires communication with the IPSI’s PKT-INT circuit in
an IPSI connected PN, a PKT-BUS failure in the IPSI connected PN causes packet traffic
in this PN, and every PN controlled by the IPSI connected PN, to fail. In the S8700
Multi-Connect configuration where some PNs are non IPSI connected, an IPSI connected
PN PKT-BUS fault should be investigated first whenever PKT-BUS problems occur in
multiple PNs.