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Configuring RTP Header Compression

Configuring Voice over IP for Cisco MC3810 Series Concentrators 7

Figure 1 RTP Header Compression

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

• Slow links

• Need to save bandwidth

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

• Change the Number of Header Compression Connections

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 passivekeyword,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.

Command Purpose

router(config-if)# ip rtp header-compression

[passive]

Enable RTP header compression.

Before RTP header compression:

20 bytes 8 bytes

20 to 160 bytes

12 bytes

Header

UDP RTP Payload

After RTP header compression:

2 to 4 bytes

20 to 160 bytes

IP/UDP/RTP header

Payload

12076

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Cisco MC3810 Installationsanleitung Seite 7