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" 我觉得VQManager实在无可挑剔,在业务环境中发挥了巨大的作用。"
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VoIP Quality Monitoring

1. Why is VoIP quality monitoring important?

VoIP, being a real-time application is more demanding on the network than traditional data applications. VoIP is susceptible to any change in the network that has a bearing on Quality of Service (QoS) metrics such as latency, packet loss and jitter. VoIP calls are transmitted over User Datagram Protocol (UDP), which does not guarantee all the packets are delivered in sequential order and could lead to poor quality calls. In extreme cases the packets may not reach the destination resulting in packet loss. All these makes VoIP call quality & QoS monitoring paramount for the enterprise, as poor quality may affect their business.

2. What are the key elements in VoIP Call Quality Monitoring?

The VoIP Quality of Service(QoS) metrics include parameters such as delay, jitter, echo, packet loss, noise and out of sequence packets. These, together with the codecs used, are used to derive the Mean Opinion Score(MOS) based on the ITU defined E-model algorithm. MOS scores can broadly classify a VoIP network to be good or poor. Typically, MOS greater than 3.5 is considered to be good. The MOS and QoS values may differ depending on the network and its usage.

3. What are the methodologies to monitor VoIP Call Quality?

VoIP quality can be monitored in two ways,

Active monitoring: This is the technique whereby VoIP calls are simulated and the endpoints' call quality are continuously monitored. Active monitoring helps the administrators determine the efficiency and capacity of the VoIP network. With active monitoring, any downtime in the network can be alerted before the actual end user faces it.
This technique is very useful in determining the strength of the VoIP network in the VoIP pre-deployment stages. At the same time, active monitoring is not efficient when real time quality monitoring of VoIP network is required since it uses the call simulation technique which further burdens the network.

Passive Monitoring: This technique involves real-time quality monitoring of VoIP calls as it uses the actual VoIP call packets that are transmitted in the network. Passive monitoring is helpful in troubleshooting the performance problems once they occur. Passive call monitoring differs from the active call management as it relies on the actual VoIP traffic and so it can detect problems only after they occur.

VoIP Monitoring