Instruction manual

Features
IP Telephony
Strata CTX General Description 10/04 79
Quality of Service (QoS) and Bandwidth
System Availability: Strata CTX100, CTX670
In any telephone system, 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 must be completed
before installing VoIP. Toshiba is not responsible for Network Voice Readiness Assessments.
More information about Voice Readiness Assessment can be found at http://www.netiq.com/
products/vm/whitepapers.asp.
CTX IP provides a number of adjustable tuning parameters dealing with sharing of network
resources, collectively referred to as Quality of Service (QoS). Expected voice QoS as it relates to
network parameters, including bandwidth, is shown in
Table 41 on page 112.
Some CTX IP voice quality adjustable parameters are listed below:
System Wide Parameters
• Software selectable G.711 or G.729A codecs with variable interval timing
• Type of Service (TOS) precedence, delay, throughput and reliability types can be individually
selected
• Differentiated Services (Diffserv) can be enabled
IP Telephone Group Parameters (256 groups)
• Voice Packet Transmission Interval
• Jitter buffer type
• Jitter buffer length
• Maximum acceptable delay
• Packet loss threshold
• IEEE802.1p
Priority Control
Priority Control can be enabled system wide. It provides a framework in which voice traffic
flowing on an IP network is given priority for processing. The CTX supports IEEE802.1p and
Differentiated Services “Diffserv” priority control protocols- selectable. In order to have priority
control processing work accurately, network equipment (router, switch, etc.) must support this
function and appropriate service must be ordered from the ISP provider or carrier.
QoS Measurement
CTX WinAdmin can measure the IPT QoS parameters listed below:
• Packets (sent/received)
• Delay (msec.)
• Jitter (msec.)
•Loss (%)