Interphase Tech RAS Communications Controller 5536 - Manual (Page 162)

Watching ISDN Ports and Channels
142 Interphase Corporation
• Fourth level: Channels available on a port
Each PRI port has one ISDN D channel. Each PRI port
also has 23 ISDN channels (North America, Japan) or
30 ISDN B channels (Europe, Australia). The digital
modem port has as many channels as there are digital
modems configured on the board.
Watching ISDN Ports and Channels
The ISDN D channel is generally used to transmit signalling
frames, such as call in progress, incoming call, or call
accepted. Watching this channel provides diagnostic
information about the ISDN connection phase. For example, if
a RAS connection fails (during either dial-in or dial-out), the
first channel to watch is the ISDN D channel.
ISDN B channels transmit data frames after an ISDN
connection is established. The first few data frames exchanged
between local and remote sites correspond to a second
connection phase to allow the establishment of the upper layer
(for example, the PPP protocol).
N
OTE
Before establishing a call, you cannot know which ISDN B
channel will be used. Therefore, to be sure to capture call
data, you must activate traces for all the ISDN channels.
To activate watching on one channel, select that channel in the
configuration panel of the SynWatch dialog box. To activate
watching on all of a port’s channels, select the port in the
configuration panel. Use the left or right mouse button as
follows to start or change watch activity: