Nortel Networks Circuit Card 311 - Manual (Page 792)

792 NT8D15 E and M Trunk card
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 not 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
See Table 307 "Pad switching algorithm" (page 792) for the pad switching
control for the various through connections and the actual port-to-port loss
introduced for connections between the E and M Trunk card and any other
IPE or PE port designated as Port B.
Figure 257 "Pad orientation" (page 793) shows the pad switching orientation.
Table 307
Pad switching algorithm
Port B pads E and M Trunk Pads Port-to-port loss (dB)
Port B
Transmit
D to A
Receive
A to D
Transmit
D to A
Receive
A to D
Port B to
E and M
E and M to
Port B
IPE line N/A N/A Out In 2.5 3.5
Note: 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 E and M Trunk card). Receive is
to the Meridian 1 from the external facility (analog-to-digital direction in the E and M Trunk card).
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
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