DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Alarms, Errors, and Troubleshooting
5-80Packet Bus Fault Isolation and Repair
5
Tools for Packet Bus Fault Isolation and
Correction
The following tools may be required on-site to perform packet bus fault isolation
and correction.
■ TN771D Maintenance/Test circuit pack for use in standalone mode, and
the connectors and cables necessary to install it (see the
Maintenance/Test Circuit Pack
section).
■ A replacement for the TN771D Maintenance/Test circuit pack in the
system may be needed. See the
A Special Precaution Concerning the
TN771D
section.
■ A backplane pin-replacement kit may be required (see
Packet Bus Fault
Correction
) If the kit is not available, replacement of a carrier may be
required.
What is the Packet Bus?
The packet bus is a set of 24 leads in the backplane of each Port Network.
Twenty of these leads are data leads, three are control leads, and one lead is a
spare. This distinction is important only for understanding why some circuit
packs are able to detect only certain faults; the distinction does not affect fault
isolation and repair. Each Port Network has its own packet bus and there is one
packet bus maintenance object (PKT-BUS) in each port network. The packet bus
is not duplicated as is the TDM Bus. There are however several spare leads on
the packet bus and, in Critical Reliability systems (duplicated PNC), these spare
leads are used to recover from some failures on the packet bus.
The packet bus carries various types of information:
■ Signaling and data traffic destined for other port-networks and/or Center
Stage Switches. The TN570 Expansion Interface circuit pack provides
packet bus access for these connections.
■ ISDN-BRI signaling information for ISDN-BRI stations, data modules and
ASAI adjunct connections. The TN556 ISDN-BRI circuit pack provides
packet bus access for these connections.
■ X.25 signaling information and data traffic to support system adjunct
applications. The TN577 Packet Gateway circuit pack provides packet
bus access for these connections.
■ ISDN-PRI signaling information carried in the D-channels of ISDN-PRI
facilities connected to the switch. The TN464F Universal DS1 circuit pack
provides packet bus access for these connections.
■ System Port traffic to support various input/output devices such as dial-up
modems and printers, as well as system adjunct applications. The TN553
Packet Data circuit pack provides packet bus access for these
connections.
