User`s guide

Configuring the WAN Interfaces
Configuring T1 lines
MultiVoice Gateway for the MAX— User’s Guide Preliminary November 23, 1998 5-3
• ISDN NFAS (Non-Facility Associated signalling)—Enables two or more T1 lines to share
a D channel. One of the lines must be configured as the primary D channel and one as the
secondary (backup) D channel.
Assigning an interface ID to NFAS lines
The NFAS ID Num is a different interface ID for each NFAS line. In most cases, the default 1
for the first line and 2 for the second line are correct. If the carrier requires different NFAS
interface IDs, type the number they specify.
Inband, robbed-bit call control mechanism
Rob Ctl is the call control mechanism for robbed-bit signalling. When you set it to Wink-Start
(the default), the switch can seize the trunk by going off hook. The local unit requires the
switch to wait for a 200 msec wink before it seizes a trunk.
Carrier switch type
Switch Type specifies the network switch providing ISDN service on a T1 PRI line. The ISDN
carrier supplies the information. For example, your carrier might support one of the following
values:
•AT&T
• NTI (Northern Telecom)
• NI-2 (National ISDN-2)
•GloBanD
• Japan
T1 line framing and encoding
Framing Mode specifies the physical-layer frame format used on the T1 line. The two possible
settings are D4 and ESF. The D4 format, also known as the superframe format, consists of 12
consecutive frames, separated by framing bits. The line may not use ISDN signalling with D4
framing. Otherwise, false framing and Yellow Alarm emulation can result. ESF specifies the
extended superframe format, consisting of 24 consecutive frames, separated by framing bits.
The ISDN specification advises that you use ESF with ISDN D-channel signalling.
The Encoding parameter sets the layer-1 line encoding used for the physical links, which
affects the way the digital signals on the line represent data. Your carrier can tell you which
encoding to use. AMI (the default) specifies Alternate Mark Inversion encoding. B8ZS
specifies Bipolar with 8-Zero Substitution. The None setting is identical to AMI, but without
density enforcement.
FDL for monitoring line quality
The telephone company uses a Facilities Data Link (FDL) protocol to monitor the quality and
performance of T1 lines. If your carrier’s maintenance devices require regular data-link reports
and the line is not configured for D4 framing, you can specify the type of protocol to use
(AT&T, ANSI, or Sprint).