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AAL2 Trunking
Figure 2-4
Figure 2-4
Figure 2-4
Note
In
Figure 2-3
The voice traffic is delivered to, or received from, the central office over short-haul T1 lines.
If CAS signaling is used, the signaling is transported across the trunk as AAL2 type 3 cells.
If CCS signaling is used, the signaling is delivered across the ATM network as AAL5 cells over separate
PVCs. VISM supports up to eight AAL5 PVCs, one for each T1/E1 line.
Other data services (such as frame relay) can be accommodated by configuring Cisco 3810, Cisco
MGX 8220, or Cisco MGX 8000 hardware with the appropriate service modules and using separate
PVCs into the packet network. The packet network routes these other data services as required.
In AAL2 trunking mode, VISM is not involved with a call agent and the functions of call control.
Multiple calls can be transported over a single PVC using the AAL2 channel identifier (CID)
mechanism. DS1/DS0s are bound to virtual channel identifier (VCI)/CIDs so that voice traffic from any
particular DS0 is automatically passed to its bound VCI/CID (and vice versa).
Cisco VISM Installation and Configuration Guide
2-4
shows a trunk with a VISM-equipped MGX 8850 shelf at each end of the trunk.
AAL2 Trunking—Two Ends
CPE
ATM Packet
PBX
AAL2 (Bearer & CAS)
V
PBX
AAL5 (CCS)
MGX 8850
with VISM
shows one trunk; however, VISM can support up to 64 trunks in this arrangement.
and
Figure
2-4, the trunk is an AAL2 nonswitched ATM PVC that carries the voice traffic.
Central Office
Network
T1 lines
V
MGX 8850
with VISM
Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004
Chapter 2
Telephony Applications Using VISM
PSTN
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