Nortel Enterprise 1000 Reference Manual page 92

Page 92 of 236 Analog Trunk Cards - NT8D14 Universal Trunk Card
553-3023-211 Standard 1.00 June 2001
Port-to-port loss configuration
Loss parameters are selected on the Universal trunk card by a switchable pad
controlled by CODEC emulation software. For convenience, the pads settings
are called "in" and "out." Pad settings are determined by the two factors listed
below: the first is under direct user control; the second is controlled indirectly.
• Class of Service is assigned in LD 14
• 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 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