Specifications

44 IBM Voice Over Frame Relay Perform Guide

FRAME-PACKING Specifies the number of voice frames that will be packed into

a single frame relay packet. The range is 1-5. The default is

The frame packing feature enables you to determine the trade-off between

efficiency (overhead) and delay. In general, each additional voice packet being

sent adds an additional 15 milliseconds to the end-to-end delay on the voice

circuit. Although this should not have a large impact on perceived voice quality, it

can create a large improvement on the efficiency of the trunk.

For example, in a frame relay network where transmission rate is 67 bps, the

actual bandwidth usage without any packing feature will be 8533 bps choosing

4800 bps vocoder rate. When packing two packets into one frame, the bandwidth

usage is reduced to 6666 bps, which represent 22% bandwidth saving. When

packing five packets into a frame, the bandwidth usage will be cut down 35% to

5547 bps.

Table 15. Efficiency of Packing using Frame Relay Protocol, 67 Packet per Second

These rates do not include any voice activity detection (VAD) saving.

These settings, while important when using a standard frame relay trunk, are

especially important when tuning the network for cell-based backbone. By

ensuring that the payload fits efficiently into the appropriate cell size, these

settings ensure a minimum amount of waste when inserting the frames into cells.

echo cancel Specifies whether or not to enable echo cancellation. You

choose either yes(1) or no(2). The default is yes.

vad Specifies the vad mode. You can choose the mode either

fixed(1), adaptive(2), or none(3). The default is adaptive.

fax on(1),off(2), nsf(3)

3.4.0.2 Voice Feature Configuration

This section summarizes the voice adapter configuration commands

To configure a voice adapter, use the following steps:

1. Specify the telco-output rule

2. Specify the dial-matching rules

3. Specify the network-output rules

4. Specify call-processing rules

5. Specify the various delay and timeout value

Use the following procedure to access the voice adapter configuration process.

Vocoder Rate Frame Relay Bandwidth Usage with Voice Frame Packing

1 Packet 2 Packet 3 Packet 4 Packet 5 Packet

4800 bps 8533 bps 6666 bps 6044 bps 5733 bps 5547bps

7470 bps 11203 bps 9336 bps 8714 bps 8403 bps 8217 bps

9600 13333 bps 11466 bps 10844 bps 10533 bps 10347 bps

16000 bps 19733 bps 17866 bps 17244 bps 16933 bps 16747 bps