Understanding RTP Header Compression
.. RTP encapsulates UDP and IP headers, and the total amount of header
information (RTP/UDP/IP) adds up to 40 bytes. Since small packets are
characteristic of multimedia streams, that is a lot of overhead. Most of
the header information does not change from packet to packet, so RTP
header compression can reduce this 40-byte header to about 5 bytes on
a link-by-link basis.
.. RTP header compression can be useful on any narrowband link.
Narrowband is usually defined by speeds less than T1.
.. Since cRTP is performed by the main processor, enabling it could cause
your CPU utilization to jump if you have high packet rates, lots of serial
interfaces, or large serial interfaces. Use this feature with caution.