AT&T DS1/DMi/ISDN-PRI Loss plan, Digital conn, PORT-TO-PORT Loss Values, 4THE Digital Loss Plan

4-4THE DIGITAL LOSS PLAN

Loss plan	pbx-eia— for private-network-only applications that use analog tie trunks or
	digital tie	trunks
	pbx-low— for use with combination tie trunks (private networks tandemed
	with public networks)
	toll — for use with connections to an analog toll office or digital toll office
Digital conn	normal	— same as the EIA options used with Generic 2
loss
	low — same as the ISL options used with Generic 2; recommended for

combination tie-trunk applications where low speech volume is a problem but echo is not a problem

For both Generic 1 and Generic 2, digital loss plans are engineered by the NEC/REC and administered at installation time. It is then the customer's responsibility to monitor the user's perceptions of the plan and to administer appropriate changes as the user’s network configuration is altered.

PORT-TO-PORT LOSS VALUES

The port-to-port loss values shown in table 4-2,Digital Loss Plan (Port-to-Port Losses), can be used to determine the correct loss between two properly terminated ports of a digital switch.

To determine the correct end-to-end loss for a tandem connection (through both an analog and digital switch), simply add up the losses in each leg. Figure 4-1,End-to-End Loss Configuration Using Combination Tie Trunks, shows a tandem network consisting of two analog switches and one digital switch, with combination tie trunks connecting the analog switch to the digital switch.

Combination tie trunks are frequently encountered when station-to-station calls are being completed. Depending on the particular facilities involved, some unexpected losses may be encountered. For the network shown in figure 4-1,if a call is made from an on-premises station (ONS) on one of the analog switches tandeming through the digital switch to an ONS on the other analog switch, an end- to-end loss of 6 dB should be measured in each direction. However, if a call is made from an ONS on the digital switch to an ONS on either one of the analog switches, an end-to-end loss of 9 dB should be measured in each direction. This 3-dB difference is a result of analog and digital loss plan differences and should be expected.

Before specific loss information is given, the following important points should be remembered:

●There are no adjustable attenuators associated with Generic 1 and Generic 2 ports. Port-to-port losses are composed of distributed losses in the ports and in the internal connection made between the ports. The loss for the internal connection is a function of the port type and the number of ports on the connection. Different port types (such as, digital CO, digital tie trunk, digital off- premises station) use the same DS1/DMI hardware.