Nortel Networks 311

790 NT8D15 E and M Trunkcard

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 DataBlock Program (LD 14). Refer to

Table304 "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 bya 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 referredto as the

ESN setting. However, the 4-wire setting is not restricted to networks

using the ESN feature. Conversely, the 2-wiresetting, oftencalled

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

(TransmissionCompensated) 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 operationof 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 fora 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