Mitel SX-200 ICP - 1.0 5020, Руководство техника

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SX-200 ICP CX/CXi Technician’s Handbook
Troubleshooting T1 Trunks (D4 DS-1)
A T1 Trunk is a digital trunking standard that supports multiple users.
Unlike analog trunks, the T-1 hardware signaling layer is independent of
trunk usage; synchronization and signaling are dealt with separately.
Figure 21: TI Trunk Synchronization
Synchronization
The T1 trunk establishes and maintains a connection between the two
systems. Sampling clocks of each partner must be synchronized.
- The Master-Slave arrangement defines the leader and follower; if
connecting to a Public Network T1, the PBX will always be a slave.
- The Stratum clock levels define the accuracy of the clock and the ability
to match with the incoming master clock signal.The higher Stratum
number synchronizes to the same or lower Stratum number. For
example, a Stratum 4 (PBX) clock synchronizes to a Stratum 3 (CO/
PBX/Channel Service Unit) clock.
- When the PBX is connecting to more than one T-1 signal, choose the
order of preference of clocking sources in Form 44, T1 Network Sync
(always choose a connection as close as possible to the defined
master source clock).