Effects Of Circuit-Pack Failures On The Packet Bus - Avaya MCC1 Maintenance Procedures

NOTE:
Every Maintenance/Test circuit pack must be of vintage TN771D or later. This circuit
pack is also used for ISDN-PRI trunk testing (M/T-DIG) and ATMS trunk testing (M/T-
ANL).
Effects of circuit-pack failures on the packet
bus
Certain faults of any of the previous circuit packs can disrupt traffic on the packet bus. Some failures
cause packet-bus problems with corresponding alarms, while others cause service outages without
alarming the packet bus (although the failed circuit pack should be alarmed).
Failures of packet-bus circuit packs affect the bus in the following ways:
• TN2312AP IP Server Interface (IPSI) — A failure of an IPSI's Packet Interface circuit
typically causes all packet traffic either within its scope or within the PN to fail. As a result:
— An IPSI-connected PN and its CSS connectivity are disabled.
— ISDN-BRI sets cannot make or receive calls.
— Communication with ASAI adjuncts fail.
— System ports are disabled.
— ISDN-PRI D-channel signaling is disabled.
If the Packet Interface circuit's fault is on its packet-bus interface, the packet bus may also alarm.
In a standard, high-, or critical-reliability system with duplicated IPSIs, one TN2312AP IPSI
circuit pack resides in each PN's control carrier. If a fault in the active IPSI's Packet Interface
circuit disrupts the packet bus, an IPSI interchange may restore service. In other cases,
replacement of the circuit pack may be required before service can be restored.
• TN570 Expansion Interface (EI) — A failure of an EI circuit pack typically causes all packet
traffic in the connected PN or CSS to fail. If the failure is on its packet-bus interface, the packet
bus may be alarmed as well.
If an active EI failure causes a packet-bus disruption in a critical-reliability system (duplicated
PNC), a PNC interchange may restore service. In other cases, replacement of the circuit pack may
be required before service is restored.
• TN556 ISDN-BRI — A failure of an ISDN-BRI circuit pack typically causes some or all ISDN-
BRI sets and data modules and/or an ASAI adjunct connected to the circuit pack to stop
functioning. If the failure is on the circuit pack's packet-bus interface, the packet bus may be
alarmed.
• TN464F Universal DS1 — A failure of a Universal DS1 circuit pack disrupts ISDN-PRI
signaling traffic carried on the D channel. The loss of that signaling may impact the pack's 23 B
channels. If the D channel supports NFAS (non-facility-associated signaling), the B channels of
up to 20 other DS1 circuit packs may also be affected. In cases where all 24 channels of the circuit
pack are B channels, packet bus-related failures may not affect the B channels, since only D-
channel signaling is carried on the packet bus. If the failure is on the circuit pack's packet-bus
interface, the packet bus may be alarmed as well.
Maintenance Procedures
December 2003
Packet and serial bus maintenance
Isolating and repairing packet-bus faults
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