Alarms, Errors, and Troubleshooting
555-233-143
4-86 Issue 1 May 2002
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:
■ TN2312 IP Server Interface (IPSI) — A failure of an IPSI’s Packet
Interface circuit typically causes all packet traffic within its scope to fail. As
a result:
— An IPSI-connected EPN 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 duplex-, high-, or critical-reliability system with duplicated IPSIs, one
TN2312 IPSI circuit pack resides in each EPN 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 EPN 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.
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