Isolating and Repairing Packet-Bus Faults
Issue 1 May 2002
4-85555-233-143
■ TN771D Maintenance/Test:
— ‘‘M/T-BD (Maintenance/Test Circuit Pack)’’ on page 8-1157
— ‘‘M/T-DIG (Maintenance/Test Digital Port)’’ on page 8-1161
— ‘‘M/T-PKT (Maintenance/Test Packet Bus Port)’’ on page 8-1175
Circuit Packs that Use the Packet Bus
This section describes the circuit packs that use the packet bus and the mutual
effects of circuit-pack and bus failures.
Seven circuit packs can use the packet bus: The MOs pertaining to each circuit
pack (described further in Chapter 9) are listed in brackets:
■ TN2312 IP Server Interface [PKT-INT] provides a server’s Ethernet
interface to an EPN’s packet bus. All traffic on the packet bus passes
through the TN2312 IPSI circuit pack’s Packet Interface circuit. This circuit
can detect some control-lead and many data-lead failures by checking for
parity errors on received data.
■ TN570 Expansion Interface [EXP-INTF] connects the EPNs in the
system. All packet traffic between PNs passes through a pair of TN570s
(one in each EPN). The EI can detect some control-lead and many
data-lead failures by way of parity errors on received data.
■ TN556, TN2198, or TN2208 ISDN-BRI [BRI-BD, BRI-PORT, ABRI-PORT,
BRI-SET, BRI-DAT, ASAI-ADJ] carries signaling information for ISDN-BRI
station sets and data modules, as well as signaling information and ASAI
messages between the server and an ASAI adjunct. An ISDN-BRI circuit
pack has the same fault-detection capabilities as a TN570 EI circuit pack.
■ TN464F Universal DS1 circuit pack [UDS1-BD, ISDN-LNK] supports
ISDN-PRI communications over an attached DS1 facility. It transports
D-channel signaling information over the packet bus, and B-channel data
over the TDM bus. The universal DS1 circuit pack has the same
fault-detection capabilities as a TN570 EI circuit pack.
■ TN771D Maintenance/Test circuit pack [M/T-BD, M/T-DIG, M/T-PKT,
M/T-ANL] is the workhorse and a critical tool of packet-bus maintenance.
This circuit pack can detect every packet-bus fault in the EPN where it
resides. In a critical-reliability system (duplicated PNC), this circuit pack
enables the reconfiguring of the packet bus around a small number of
failed leads. The TN771D circuit pack provides a stand-alone mode (one
not involving indirect communication with the server, via the IPSI) for
inspecting packet-bus faults.
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).
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