Voice Compression Module - 3Com SuperStack II PathBuilder S330 Reference Manual

Voice Compression
Module
To set up multi-point video conferencing, you build virtual circuits (defined by
transmit and receive vpi/vci combinations) between the remote units and between
the remote units and the central unit. The remote units can use the same vpi/vci to
communicate with the central unit (one at a time), or you can allocate different
channels and set up separate virtual connections to each remote unit.
Table 36,Table 37, Table 38, and Table 39 list possible routing tables when the
remote units have been allocated different channels on the central unit's T1 line.
Table 36 Multi-point Video Conferencing Routing Table (Remote Unit #1111)
Destination # Tx vpi/vci
2222 0/1
3333 0/1
4444 0/1
Table 37 Multi-point Video Conferencing Routing Table (Remote Unit #2222)
Destination # Tx vpi/vci
1111 0/2
3333 0/2
4444 0/6
Table 38 Multi-point Video Conferencing Routing Table (Remote Unit #3333)
Destination # Tx vpi/vci
1111 0/3
2222 0/3
4444 0/12
Table 39 Multi-point Video Conferencing Routing Table (Central Unit #4444)
Source Tx vpi/vci
1111 0/2
2222 0/7
3333 0/13
The optional Voice Compression module (VCM) provides one T1 or E1 port. It is
similar in function to the CBR module, but it employs compression algorithms that
allow more voice calls to be placed through the same bandwidth.
The incoming voice signal is carried on one or more of the T1/E1 port's 24/31 DS0
channels. The voice data in each DS0 channel is in PCM format. This data is
compressed by the DSP, and the output from the DSP is encapsulated into FRF.11
packets by the host CPU on the VCM daughtercard. The packets are then passed
to the mother board through the PCI interface, handed over to the AAL5 SAR, and
transmitted to the ATM interface.
In the reverse direction, compressed voice packets are received by the SAR on the
ATM interface in FRF.11 format. The packets are then passed to the VCM
daughtercard via the PCI interface. The packets are unpacked by the daughtercard
CPU before they are handed to the DSP, which decompressed the voice data and
plays out the voice onto the T1/E1 PCM interface.

Voice Compression Module

Rx vpi/vci Speed
0/2 384k
0/3 384k
0/2 384k
Rx vpi/vci Speed
0/1 384k
0/3 384k
0/7 384k
Rx vpi/vci Speed
0/1 384k
0/2 384k
0/13 384k
Rx vpi/vci DSOs
0/1 channels 0-5
0/6 channels 6-11
0/12 channels 12-17
241
Status
idle
idle
active
Status
idle
idle
active
Status
idle
idle
active