NEC NEAX 2000 IPS - Page 290

Chapter 13 Voice Over IP (VoIP)
Page 13- 32 NEAX 2000 IPS Request for Proposal (RFP) Reference Guide
NDA-24349, Issue 4
packet is sent to the trunk route for each system or Point Code in the network. If traffic is
present on either IP stations or trunk routes, no “Keep Alive” packet is generated.
Bandwidth utilization
The following chart shows the amount of bandwidth for IP overhead per the fill times set in the
PBX system. The higher the fill time used, better performance from the PBX and IP network
can be realized due to the smaller number, yet larger (in size) packets generated.
Filler Time
Codec
10 msec 20 msec 30 msec 40 msec
G.711 (64 Kbps) 32 Kbps 16 Kbps 10.67 Kbps 8 Kbps
G.729a (8 Kbps) 32 Kbps 16 Kbps 10.67 Kbps 8 Kbps
G.723.1 (6.3 Kbps) N/A N/A 10.67 Kbps N/A
G.723.1 (5.3 Kbps) N/A N/A 10.67 Kbps N/A
This chart shows the total amount of bandwidth in layer 3 per voice call during the transmit
stream from an IP trunk or IP station. The value shown is based on the fill time from the table
above and the bandwidth required by the encoding/decoding algorithm that is used (codec).
Total Bandwidth per transmit stream
Codec
10 msec 20 msec 30 msec 40 msec
G.711 (64 Kbps) 96 Kbps 80 Kbps 74.67 Kbps 72 Kbps
G.729a (8 Kbps) 40 Kbps 24 Kbps 18.67 Kbps 16 Kbps
G.723.1 (6.3 Kbps) N/A N/A 16.97 Kbps N/A
G.723.1 (5.3 Kbps) N/A N/A 15.97 Kbps N/A
This chart shows bandwidth usage (G.729A) based on an idle state followed by a keep alive
message with a call setup and voice usage next. Time is not to scale.
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S1
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Bandwidth in
Kbps
Time (not to scale)
Bandwidth per Process
Keep
Call Setu
p
Voice Usa
g
e
Call
T
ea
r
dow
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