Configuring IPHC
IPHC is a host-to-host protocol used to carry real-time multimedia services such as voice and video over IP networks. To decrease the bandwidth consumed by packet headers, you can enable IPHC on PPP links to compress RTP (including IP, UDP, and RTP) headers or TCP headers. The following uses RTP header compression to describe how compression operates.
RTP is a UDP protocol using fixed port number and format. An RTP packet comprises a 40-byte header and a data section. The 40-byte header, which is composed of a 20-byte IP header, an 8-byte UDP header, and a 12-byte RTP header, is large compared with the payload, which is usually 20 bytes to 160 bytes in size. To reduce bandwidth consumption, use IPHC to compress RTP packet headers. After compression, the 40-byte header can be reduced to 2 to 5 bytes. If the payload is 40 bytes, the compression ratio will be (40+40) / (40+5), about 1.78, which is very efficient.
To configure IPHC:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | N/A |
3. Enable IP header compression. | ppp compression iphc [ nonstandard ] | By default, IP header compression is disabled. |
4. Set the maximum number of connections allowed by TCP header compression. | ppp compression iphc tcp-connections number | Optional. The default setting is 16. |
5. Set the maximum number of connections allowed by RTP header compression. | ppp compression iphc rtp-connections number | Optional. The default setting is 16. |