Nortel Networks Circuit Card 311 - Manual (Page 790)

790 NT8D15 E and M Trunk card
The trunk type is selected by making service change entries in the Route
Data Block Program LD 16. The companding mode is selected by making
service change entries in the Trunk Data Block Program (LD 14). Refer to
Table 304 "E and M Trunk card - jumper strap settings" (page 788) to select
the proper values for the trunk type being employed. Refer to the Software
Input/Output Reference — Administration (NN43001-611) for LD 14 and
LD 16 service change instructions.
Port-to-port loss configuration
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 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 01.04 Standard
Release 5.0 23 May 2008
Copyright © 2003-2008, Nortel Networks
.