Toshiba Strata CTX, Руководство по программированию

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Applications, Tips and Tricks
IP Telephone Quality of Service (QoS) Programming
Strata CTX Programming - Part 4: Appendices 04/03
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IP Telephone Quality of Service (QoS) Programming
Deploying many IP telephones on a data LAN can have some unexpected pitfalls if the network does not
have the bandwidth and speed required to handle VoIP traffic. To prevent delay, jitter, and data loss for
VoIP traffic and retain the performance of your other business-critical network applications a network
Voice Readiness Assessment should completed before installing VoIP.
Important!
Voice Readiness Assessments are the responsibility of the installing TSD dealer. Toshiba is
not responsible for supporting problems which occur because the network on which the IP
telephones are installed does not meet VoIP packet requirements.
CTX IP provides a number of adjustable tuning parameters dealing with sharing of network resources,
collectively referred to as Quality of Service (QoS). Some CTX IP voice quality and packet priority
parameters that can be adjusted are described below:
General QoS Adjustments
The CTX provides parameters that can be adjusted to improve IP voice quality. These are normally kept at
default but may be adjusted as necessary to modify IP voice quality. Set each item individually and then
test for voice quality improvements each time a parameter is changed.
1. In WinAdmin, select IP Telephone > Station IP Data (Program 250) “08 Audio Codec” and select the
codec that should be enabled for individual IP telephones. The G711 provides the best voice quality but
requires the most network bandwidth. Usually G.729A is used when IP telephones are connected
remotely.
2. In WinAdmin, select IP Telephone > System IP data (Program 150) and select the 11 BIPU/IPT VQ
mode setting.
3. You can assign a Voice Packet Table to individual IP telephones in IP Telephone > Station IP Data
(Program 250–07) Voice Packet Table. In WinAdmin, select IP Telephone > Voice Packet
Configuration (Program 152) and configure up to 256 different tables (see below).
Voice Packet Configuration Table (Program 152)
Normally the default table settings are used. If experiencing voice quality problems, set each item
individually and then test for voice quality improvements each time a parameter is changed. The default
settings are shown below. The tables in this program must be assigned to individual IP telephones in IP
Telephone > Station IP Data (Program 152) for them to be used by the CTX.
Voice Packet Configuration Parameters defaults:
• Voice Packet Transmission Interval – 20 msec
• Jitter buffer type – adaptive
• Jitter buffer length – 100 (smooth out packet playback)
• Maximum acceptable delay – 200 (not adjustable in CTX R2.0)
• Packet loss threshold – 5
• Packet loss ratio – 5 (not adjustable in CTX R2.0).
• Measurement period – 1000 (not adjustable in CTX R2.0).