Cisco Systems 3600 manual Enable RTP Header Compression on a Serial Interface

Configure RTP Header Compression

You should configure RTP header compression if the following conditions exist in your network:

Note RTP header compression should not be used on links greater than 2 Mbps.

Perform the following tasks to configure RTP header compression for Voice over IP. The first task is required; the second task is optional.

Enable RTP Header Compression on a Serial Interface

To use RTP header compression, you need to enable compression on both ends of a serial connection. To enable RTP header compression, use the following command in interface configuration mode:

If you include the passive keyword, the software compresses outgoing RTP packets only if incoming RTP packets on the same interface are compressed. If you use the command without the passive keyword, the software compresses all RTP traffic.

Change the Number of Header Compression Connections

By default, the software supports a total of 16 RTP header compression connections on an interface. To specify a different number of RTP header compression connections, use the following command in interface configuration mode:

RTP Header Compression Configuration Example

The following example enables RTP header compression for a serial interface:

interface 0

ip rtp header-compression encapsulation ppp

ip rtp compression-connections 25

For more information about RTP header compression, see the “Configuring IP Multicast Routing” chapter of the Network Protocols Configuration Guide, Part 1.

Configuring Voice over IP for the Cisco 3600 Series VC-21