Nortel Networks 1000 User Manual

Page 625

Configuration

625

The VNL class of service is assigned at the prompt CLS with the response
VNL. The non-VNL class of service is assigned at prompt CLS by selecting
either the Transmission Compensated (TRC) or Non-Transmission
Compensated (NTC) response.

Non-VNL trunks are assigned a TRC or NTC class of service to ensure
stability and minimize echo when connecting to long-haul trunks, such as
TIE trunks. The class of service determines the operation of the switchable
pads contained in each unit. They are assigned as follows:

•

TRC for a 2-wire non-VNL trunk facility with a loss of greater than 2
dB, or for which impedance compensation is provided, or for a 4-wire
non-VNL facility

•

NTC for a 2-wire, non-VNL trunk facility with a loss of less than 2 dB,
or when impedance compensation is not provided

See

Table 238 "Pad switching algorithm" (page 625)

for the pad switching

control for the various through connections and the actual port-to-port loss
introduced for connections between the Universal trunk card and any other
IPE or PE port designated as Port B.

Table 238
Pad switching algorithm

Port B pads

Universal Trunk
Pads

Port-to-port loss (dB)

Port B

Transmit
D to A

Receive
A to D

Transmi
D to A

Receive
A to D

Port B to
Universal
trunk
card

Universal
trunk
card to
Port B

IPE line

N/A

Out

0.5

Universal trunk (TRC)

Out

IPE TIE (VNL)

Out

PE line

N/A

Out

Note 1: Transmit and receive designations are from and to the Meridian 1. Transmit is from the
Meridian 1 to the external facility (digital-to-analog direction in the Universal trunk card). Receive is
to the Meridian 1 from the external facility (analog-to-digital direction in the Universal

Note 2: When Port B is the call originating port. If the Universal trunk card is the originating port, the
UTC pads are out, the Port B (PE CO/FX/WATS) pads are in.

Nortel Communication Server 1000

Circuit Card Reference

NN43001-311

02.06

Standard

27 August 2008