Specifications
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Cisco MGX 8260 Command Line Interface Guide
Release 1.2, Part Number 78-10987-01 Rev. B0, January, 2002
Chapter 5 Call Control
Managing ISDN D Channels
Figure 5-5 D Channel to Media Gateway Controller
Each BSC contains 168 T1 lines, each a potential Primary Rate ISDN line. An ISDN line contains 24
channels, one of which is the D Channel that carries the signaling information for the other 23 channels.
The BSC card can terminate a D Channel signaling stack and pass the payload to a Media Gateway
Controller, via the SCC, using a backhaul session.
The following procedures describe how to configure a D Channel for a backhaul session. The
procedures assume you already have a DS3 line and have provisioned a PRI ISDN line on one of its
circuits. ISDN D Channels can be difficult to configure because they have many settings, so the MGX
8260 Media Gateway simplifies the process by grouping common settings into two types of profiles:
• Digital Link Service Access Profile
• Media Access Control Service Access Profile
The Digital Link Service Access Profile (DLSAP) and Media Access Control Service Access Profile
(MACSAP) profiles define different levels of the ISDN protocol stack (see Figure 5-6).
Figure 5-6 DLSAP and MACSAP Interfaces
When adding D Channels, you simply specify suitable profiles that contain the desired configuration set.
You can create profiles using default settings that accommodate the signaling requirements for common
applications.
D Channel Configuration Tasks
The MGX 8260 Media Gateway simplifies the process of creating D Channels with DLSAP and
MACSAP profiles. These profiles provide a template of parameter settings that you apply when adding
D Channels. Changes you make to the profiles only apply to lines you subsequently add, not to lines
that already exist. If you want to change the configuration of a D Channel, delete it first and then
recreate a new one using the new template.
The following describes the high-level procedure for configuring a D Channel on an existing DS3
trunk:
Step 1 Define a DLSAP profile.
Step 2 Define a MACSAP profile.
Step 3 Define a D Channel on a PRI ISDN line within the DS3 trunk, using the profiles you defined in
Steps 1 and 2.
Channel
Bank
MGCBSC
DS3 Session
SCC
3
1931
31944
Q.931
D
LSAP interface
D-Channel
LAPD
M
ACSAP interface