DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Alarms, Errors, and Troubleshooting
5-86Packet Bus Fault Isolation and Repair
5
packet bus failure a c atastrophic problem . The only way an EPN packet bus
failure can affect TDM traffic is via possib le impact on system respon se time in a
large switch due to runnin g of ISDN-BRI endpoint maintenance. This should
rarely happen bec ause the packet bus maintenanc e software is able to prevent
this for most faults (see the next section).
If packet bus failure oc curs in the PPN, the impact is much more wid espread.
Because the PPN packet bus c arries the signaling and c ontrol links for all EPNs,
PPN packet bus failure effectively removes all the EPNs from service, inc luding
both TDM and packet b usses. Packet bus traffic in the PPN is also disrup ted.
!CAUTION:

Packet bus fault correction and fault isolation often involve circui t pack

removal, which is destructive to service. Minimize time devoted to

destructive proc edures by the use of non-destruc tive ones where possible.

Packet Bus Maintenance Software
Packet bus maintenance software involves the usual set of maintenanc e object
error conditions, tests, and alarms. These are described in “PKT-BUS” in Chapter
9. Because a packet b us failure can cause all BRI/ASAI endpoints in the affec ted
Port Network, and all their associated p orts and circuit packs, to report failures,
special care must b e taken to ensure that the flood of error messages d oes not
overload the system and interfere with TDM Bus traffic .

When such a failure

occurs

, circuit pac k maintenance is affected in the following manner:
■In-line errors for the following MOs which ind icate possible p acket bus
failures are logged but

not acted upon:

BRI-BD, PGATE-BD, PDATA-BD,
UDS1-BD.
■In-line errors for the following MOs which ind icate possible p acket bus
failures are

neither logged nor ac ted upon:

BRI-PORT, ABRI-PORT,
PGATE-PT, PDATA-PT, ISD N-LNK .
■All in-line errors for the following MOs are

neither logged nor ac ted upon:

BRI-SET, BRI-DAT, ASAI-ADJ.
■Circuit pack and port in-line errors that are not related to the p acket bus,
or that indicate a circ uit pack failure, are acted up on in the normal fashion.
■Periodic and sched uled backg round maintenance is not affected .
■Foreground maintenance (for example, c ommands executed from the
terminal) is not affected.
These interactions allow normal non-pac ket system traffic to continue unaffec ted,
and they reduce the numb er of entries into the Error/Alarm Logs. If the pac ket
bus failure is caused b y a failed circuit p ack, errors against the circ uit pack
should appear in the Error/Alarm Log s as an aid for fault isolation. The above
strategy is implemented wh en:
■In-line errors indicate a possib le packet bus failure rep orted by two or
more Packet circuit pac ks.