3Com VCX V7122 User Manual page 153

Note: It is possible to configure both gateways to also operate in symmetric mode. To do so,
set 'EnableTDMOverIP' to 1 and configure the Tel to IP Routing tables in both VCX V7122
gateways. In this mode, each gateway (after it is reset) initiates calls to the second gateway.
The first call for each B-channel is answered by the second gateway.
The VCX V7122 monitors the established connections continuously. If for some reason one
or more calls are released, the gateway automatically reestablishes these "broken"
connections. In addition, when a failure in a physical trunk or in the IP network occurs, the
VCX V7122 gateways reestablish the tunneling connections as soon as the network
restores.
Note: It is recommended to use the keep-alive mechanism for each connection by activating
"session expires" timeout, and using Reinvite messages.
By utilizing the 'Profiles' mechanism (see
can configure the TDM Tunneling feature to choose different settings, based on a timeslot or
groups of timeslots. For example, you can use low-bit-rate vocoders to transport voice, and
'Transparent' coder to transport data (e.g., for D-channel). You can also use Profiles to
assign ToS (for DiffServ) per source, a time-slot carrying data or signaling gets a higher
priority value than a time-slot carrying voice.
For tunneling of E1/T1 CAS trunks enable RFC 2833 CAS relay mode
(CASTransportType = 1).
Figure 58 and Figure 59
implementing TDM Tunneling for four E1 spans. Note that in this example both gateways are
dedicated to TDM tunneling.
Figure 58 ini File Example for TDM Tunneling (Originating Side)
EnableTDMOverIP = 1
;E1_TRANSPARENT_31
ProtocolType_0 = 5
ProtocolType_1 = 5
ProtocolType_2 = 5
ProtocolType_3 = 5
prefix = '*,10.8.24.12' ;(IP address of the VCX V7122 in the opposite location)
; Channel selection by Phone number
ChannelSelectMode = 0
;Profiles can be used do define different coders per B-channels, such as Transparent
; coder for B-channels (time slot 16) that carries PRI signaling.
TrunkGroup = 0/1-31,1000,1
TrunkGroup = 1/1-31,2000,1
TrunkGroup = 2/1-31,3000,1
TrunkGroup = 3/1-31,4000,1
TrunkGroup = 0/16-16,7000,2
TrunkGroup = 1/16-16,7001,2
TrunkGroup = 2/16-16,7002,2
TrunkGroup = 3/16-16,7003,2
CoderName = 'g7231'
CoderName = 'Transparent'
3Com VCX V7122 SIP VoIP Gateway User Manual
Configuring the Profile Definitions
show an example of ini files for two VCX V7122 gateways
on page 58) you
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