Nortel Networks 1000 - Manual (Page 712)

712 NT8D15 E and M Trunk card
Loss parameters are selected on the E and M trunk card by a switchable
pad controlled by CODEC emulation software. The pads settings are
called "in" and "out." Pad settings are determined by the three factors
listed below: the first two are under direct user control; the third is
controlled indirectly.
• Class of Service is assigned in LD 14.
•
Facility termination is selected (2-wire or 4-wire) in LD 14 (the 2-wire
setting provides 0.5 dB more loss in each direction of transmission for
echo control).
Note: Facilities associated with the Nortel Networks Electronic
Switched Network (ESN) are recommended to be 4-wire for optimum
transmission so, the 4-wire setting is generally referred to as the
ESN setting. However, the 4-wire setting is not restricted to networks
using the ESN feature. Conversely, the 2-wire setting, often called
non-ESN, can be used on certain trunks in an ESN environment.
• Port-to-port connection loss is automatically set by software on the
basis of the port type selected in LD 16; only the port type is set by the
user.
The transmission properties of each trunk are characterized by the class of
service assigned in LD 14. Transmission properties can be Via Net Loss
(VNL) or non-Via Net Loss (non-VNL).
The VNL class of service is assigned at the CLS prompt by typing
VNL. The non-VNL class of service is assigned at the CLS prompt by
typing TRC (Transmission Compensated) or NTC (Non-Transmission
Compensated).
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.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.