Acer ISDN 128 Surf USB Bedienungsanleitung PDF herunterladen (Seite 12)

5.4.1 Simulation of VoIP flows

With simulation utilities like CRUDE/RUDE we can not hollow exactly simulate VoIP flows

(with signalization etc.) but we can good approximate a real traffic. In Tab. 5 you can see the

most applied codec for VoIP, bitrates and number of Samples per period.

Codec

Speed

[kbit/s]

Delay of

Algoritmh

[ms]

Alg.(modulation) samples/Time

G.711 64 0,125 PCM 8bits/125 s

G.723.1 5,3 37,5 MP-MLQ 20Bytes/30ms

G.723.1 6,3 37,5 ACELP 24Bytes/30ms

G.726 32 0,125 ADPCM 2-5bits/125 s

G.728 16 0,625 LD-CELP 16bits/625 s

G.729 8 15 CS-ACELP 10Bytes/10ms

Tab. 5 - Summary of codecs in VoIP

For Test i choose most apply G.723.1 codec with rate 6,3 kbit/s. This flow we can approximate

with RUDE/CRUDE utilities.

5.4.2 Set-up RUDE/CRUDE for test

RUDE have a configuration file for example config.cfg. In this file we can specify

parameters of flow. See below Tab. 6

## FLOW 1: (flow ID = 10 with address of flow 3002) G.723.1 6,3 kbit/s

## Starts 1 second after the START time with following parameters:

## 33 packets/second with 24 bytes/packet = 792bytes/sec = 6,34 kbit/s

## from IP address 192.168.0.52 on port 10001

## Ends on 180s after start

1000 0010 ON 3002 192.168.0.51:10001 CONSTANT 24 33

180000 0030 OFF

Tab. 6 -Example configuration of flows in RUDE config file for G.723.1 6,3 kbit/s

The time of test we set to 3 min, while in telecommunication was measured average time of

calls to 2 - 3 min. If we measured error rate of packets. We would set longer time of test. For

example 1h or more. In the tab. 3 you can see the result of test for flow G.723.1 6,3 kbit/s. The

higher speed of flow (round 14 kbit/s) is caused payloads of IP/UPD packets (40Bytes).

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Acer ISDN 128 Surf USB Bedienungsanleitung Seite 12