Bandwidth Requirements
Various tradeoffs go into selecting the parameters for a VoIP implementation,
each of which affect voice quality and bandwidth. These include:
■ Sample period—Each packet represents a period of time. Longer
periods mean that fewer headers have to be sent, but add delay while
accumulating samples. Shorter periods mean more header overhead,
but less delay.
■ Packets per second—One second divided by the sample period.
■ CODEC—Each coding protocol uses more or less bandwidth and
offers more or less quality. See Table 2-1 for details.
■ IP/UDP/RTP overhead—40 B, or 4 B if using cRTP with checksum, or
2B if using cRTP without checksum.
■ Data Link overhead—Ethernet uses 18 B. This varies by protocol.