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Cisco VISM Installation and Configuration Guide
Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004
Chapter3 VISM Functional Description
TDM Line-Handling Function
Figure3-1 VISM Detailed Functional Blocks
TDM Line-Handling Function
The TDM line-handling function provides the physical layer interface to the T1/E1 lines and handles th e
following features:
•Framing
•Line codes
•Physical layer alarms and failures
•Clocking
•Loopbacks
•Distinguishes between bearer and CCS signaling channels
Outgoing traffic—in from the TDM network and out to the packet network—is pro ce ssed by the T1/E1
framers where each DS0 is extracted from its DS1 stream and is routed by a DS0 switch to the
appropriate function. Bearer DS0s are routed to the bearer proces sing function. CCS signaling DS0s are
routed to the TDM signaling function.
Outgoing traffic—in from the packet network and out to the TDM network—is p rocessed in the opposite
manner. The DS0s received from the ATM side are inserted into their respective DS1s and transmitted
over the appropriate line in the TDM network.
TDM Line
Handling DS0
Switch
Embedded Management Functions
Bearer
Processing
Bearer
Packetization
(SSCS)
ATM CPS
(SAR)
Signaling Connection
Handling * Resource
Coordination *
To Call Agent
*
Signal backhaul xGCP (CAS), Q.931 (PRI) *
Call setup/ teardown xGCP *
SRCP *
5
3235
To ATM
Network
User Inputs
(CLI, CWM, SNMP)
T1/E1
Lines
CAS CAS (AAL2, Type 3) **
CCS (AAL5) **
CCS
Key:
* VoIP Switching and
Switched AAL2 PVC
modes only
** Trunking mode only