Nortel DMS-100 Series Maintenance Manual page 241

Instead of using a metallic path between the subscriber line and the test
equipment, access is established by replicating the digital data streams on the
line.
A DTA monitors the following data on an Star Module ISDN line
• D-channel
• circuit-switched B-channels
• packet-switched B-channels
Two streams of digital data are monitored:
• the data flowing toward the subscriber (downstream data)
• the data flowing away from the subscriber (upstream data)
The monitoring capability has no effect on the streams being monitored.
Monitoring is performed with a commercially available protocol analyzer.
Two streams of digital data are derived from the monitored channel:
• downstream - the data flowing toward the subscriber and away from the
switch
• upstream - the data flowing toward the switch and away from the
subscriber
Each of these streams is made available to the protocol analyzer through
• two channels of a DS-1 interface supported by the host XPM
• the B1 and B2 channels of an ISDN line card in the Star Module
The monitoring point for the upstream and downstream data of the loop
channels (B or D) is the switching matrix portion of the SMC card in the Star
Module. The monitoring point for the upstream data of the Bd channels is the
timeswitch of the host XPM. The downstream data is derived from the
timeswitch at the DS-1.
The following restrictions apply for use of DTA connections on a Star Module:
• only one DTA connection on each Star Module is allowed
• DTA monitoring on a Bd channel is not supported
The following figure identifies the two scenarios for DTA monitoring of Star
Module ISDN lines.
Star Remote System manual maintenance 7-37
DMS-100 Family NA100 Star Remote System XPM15 and up