Avaya BCM 2.0 IP Telephony Instrukcja Użytkownika Pobierz pdf (Strona 10)

10 Overview

Enterprise Edge 2.0 IP Telephony Configuration Guide P0911590 Issue 02

Network Quality of Service

Enterprise Edge VoIP Gateway uses a method like the ITU-T Recommendation

G.107, the E-Model, to determine the voice quality. This model evaluates the end-

to-end network transmission performance and outputs a scalar rating “R” for the

network transmission quality. The packet loss and latency of the end-to-end

network determine “R”. The model correlates the network objective measure “R”,

with the subjective QoS metric for voice quality, MOS or the Mean Opinion Score.

This model provides an effective traffic building mechanism by activating the

Fallback to Circuit-Switched Voice Facilities feature at call set up to avoid quality

of service degradation. New calls fall back when the configured MOS values for all

codecs are below the threshold.

The model is the reason for compression characteristics of the codecs. Each codec

delivers a different MOS for the same network quality.

Network Monitoring

The VoIP Gateway network monitoring function measures the quality of service

between the local and all remote gateways on a continuous basis. The network

monitoring function exchanges UDP probe packets between all monitored

gateways to collect the network statistics for each remote location. All the packets

make a round trip from the Sender to Receiver and back to the Sender. From this

information, you can calculate the latency and loss in the network for a distinct

location.

Note 1: Quality of Service monitoring is not supported for non-Enterprise Edge

product locations and must be disabled.

Note 2: The Quality of Service threshold is configurable per remote gateway.

Note 3: Fallback starts for all new originating calls if the QoS of any monitored

gateway is below its threshold.

Note 4: The fallback decision is made only at the originating gateway using the QoS

thresholds monitored at the originating gateway for the destination gateway.

VoIP Gateway allows for manual configuration of QoS thresholds depending on the

customer preference between cost and voice quality. The Engineering guidelines

chapter on page 15 provides the guidelines to determine the quality of service that

supported for any given network.

Quality of service parameters

Quality of Service is depends on end-to-end network performance and available

bandwidth. A number of parameters determine the VoIP Gateway QoS over the

data network.

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Avaya BCM 2.0 IP Telephony Instrukcja Użytkownika Strona 10