Avaya IP Telephony Guía de configuración descargar pdf (Pagina 200)

200 Quality of Service

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Network Quality of Service

This information under the headings in this section provides details about the quality of service

aspects of networking.

• “Network monitoring” on page 200

• “Quality of Service parameters” on page 201

• “Fallback to PSTN” on page 201

Business Communications Manager 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 process 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 supported only on Business Communications Manager,

M1 with IPT card, and i20xx.

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.

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Avaya IP Telephony Guía de configuración Pagina 200