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Problem: Packet Loss

Packet Loss can occur for a variety of reasons including link failure, high levels of congestion that lead to buffer overflow in routers, Random Early Detection (RED), Ethernet problems, and the occasional misrouted packet

In depth discussion of packet loss distribution


Packet Loss causes degradation in voice quality. If packet loss concealment (PLC) is used then isolated losses may be less noticeable.

Example G.711 audio file - 10% packet loss:

Packet Loss typically occurs in bursts of 20-30% loss lasting 1-3 seconds. This may mean that the average packet loss rate for a call appears low although the user reports call quality problems.

Example G.711 with PLC audio file - bursty packet loss


Try and identify the source of packet loss by examining packet metrics available from switches and routers along the voice path.

If packet loss is accompanied by a high level of jitter or packet loss is very bursty then the problem may be congestion related.

If packet loss is present when the jitter level is very low or if the problem is specifically associated with one or more users on a specific Ethernet switch then check for Ethernet problems.


Network Analyzer, VQmon

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