Instruction manual

The following control lines are used on the main link interface:
• The RTS line, which is asserted as long as the DV-MUX3 is powered.
• The DTR and RI lines, used only in the dial-up mode.
Dial-up Mode The dial-up mode allows the DV-MUX3 to operate over the Public Switched Tele-
phone Network (PSTN), using dial-up modems to transmit the main link data over
standard PSTN lines.
The dial-up mode is available only when the main link interface is V.35 or RS-232.
In this mode, the DV-MUX3 asserts the DTR line of its main link interface when
payload traffic (from the voice or data channels) must be transmitted. This causes
the modem to dial a number preprogrammed by the user, and thus to set up a con-
nection to the remote DV-MUX3. When the remote DV-MUX3 senses the asser-
tion of the RI line in its main link interface (indication of incoming call provided
by the dial-up modem), it synchronizes to the other DV-MUX3 and starts normal
data transfer. When payload traffic stops, the DV-MUX3 switchesits DTR lineoff,
causing the modem to disconnect the link.
Bandwidth
Allocation
Bandwidth allocation is based on the automatic identification of the main link
clock rate. After successful identification of the main link rate, the DV-MUX3 as-
signs the bandwidth required by the voice channels (as selected by the user), and
uses the remaining main link bandwidth (less the linkmanagement and supervision
overhead) to transmit the data channel. The overhead is 0.8 kbps for main link data
rates of 9.6 to 32 kbps, 1.6 kbps for data rates of 48 to 128 kbps, and 3.2 kbps for
data rates higher than 128 kbps.
To maximize the throughput of the data channel beyond what is available with
standard multiplexers, the DV-MUX3 has three user-selectable bandwidth alloca-
tion modes:
• Adaptive mode: the DV-MUX3 monitors the use of the voice channels and
assigns the required bandwidth on demand. Therefore, when both voice
channels are idle, their bandwidth is temporarily reassigned to the data chan-
nel. These changes are smoothly made without disrupting in any way the
flow of traffic.
The state of the voice channels is determined by the channel control signal
transmitted end-to-end:
°
For a voice channel equipped with FXO interface, the channel control signal
generated by the channel indicates the reception of ringing by that channel.
The control signal received by that channel indicates the detection of a sub-
scriber off-hook condition by the FXS interface of the voice channel located
at the other end of the link (off-hook includes pulse dialing).
°
For a voice channel equipped with FXS interface, the channel control sig-
nal generated by that channel indicates the detection of an off-hook con-
dition (including pulse dialing). The control signal received by that chan-
nel indicates either the reception of ringing by the FXO interface of the
voice channel located at the other end of the link (when the other end is
equipped with an FXO interface), or the detection of a subscriber off-hook
condition (when the other end is also equipped with an FXS interface), or
the detection of the M signal from a remote E&M interface.
CHAPTER 1 - INTRODUCTION
1-4 DV-MUX3 Installation and Operation Manual