Codec and Bandwidth

Codec and Bandwidth

Bandwidth dimensioning in IP networks should support a calculated standard bit rate for the
expected speech and application data flow. Overload situations can be handled with
additional quality assurance procedures.

Let's look at an example: a 10 ms G.729 codec frame is encapsulated in an IP packet and
sent through a standard Ethernet network. A 66 byte overhead is used for 10 byte of speech
payload that corresponds to a ratio of 87 % to 13 % for overhead and payload per ethernet
frame. 66 Byte plus 10 byte result in 76 byte or 608 bits per 10ms - that´s a gross bit rate of
60.8 kbps. For a full duplex link twice this value, i.e., around 120 kbps of bandwidth must be
assigned.