Operation
61181041L3-5A
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OPERATION
The DS3-PSM serves as an ATM network interface. The ATM cells are packaged at the access
module and then either switched to another access slot or transported to the Wide Area
Network (WAN) where they are direct mapped into an unchannelized DS3 pipe. The DS3-PSM
supports 224 local subscribers out of a single 23-inch Total Access 3000 chassis or up to
1344 subscribers with local subtending.
Performance monitoring data is collected by both the working and protection DS3-PSM units
and stored in local volatile memory. All required parameters listed in ANSI T1.231 are
supported.
Diagnostics
The DS3-PSM monitors DS3 line conditions for anomalies and/or Far End Alarm Channel
(FEAC) codes in accordance with ANSI T1.107-1995. Alarm and status code words are trans-
mitted by the DS3-PSM to the PCU for alarm processing when the specific alarm or status
conditions are met. The DS3-PSM provides the following test options:
• DS3 Loopback Test
• PVC/PVP Test
• Single Card Cell Generation Test
Alarms
Loss Of Signal (LOS) and Out Of Frame (OOF) detected on the incoming DS3 signal causes an
Alarm Indication Signal (AIS) to be substituted in all low-speed tributaries.
AIS
The DS3-PSM inserts AIS in both the downstream and upstream directions. Downstream AIS
is inserted under any of the following conditions:
• Activation of any tributary network loop
• DS3-PSM is in an Out of Service-Unassigned state
• During a T3 APS switch, the DS3-PSM going offline inserts a 32 msec burst of AIS to the
low-speed tributaries, forcing the access modules to switch to the new online DS3-PSM
• One of the following RX conditions is detected:
– LOS: Loss of T3 signal that is needed to supply the ATM tributaries
– OOF: Out Of Frame condition exists on a signal needed to supply the ATM tributaries
– RCV AIS: AIS is received on incoming T3 signal that is needed to supply the ATM
tributaries
– RCV Idle Signal: Idle signal is received on the incoming T3 signal that is needed to supply
the ATM tributaries
Upstream AIS is inserted under either of the following conditions:
• An assigned channel where the module is not supplying clock
• Activation of Local Loopback on the DS3-PSM causes the transmission of T3 AIS toward
the network on the DS3 interface
