Table Of Contents

Configuring Distributed Compressed Real-Time Protocol

Distributed CRTP Configuration Task List

Changing the Number of Header Compression Connections

Distributed CRTP Configuration Examples

Distributed Compressed RTP Header Compression Example

Express TCP Header Compression Example

Configuring Distributed Compressed Real-Time Protocol

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This chapter describes the tasks for configuring the Distributed Compressed Real-Time Protocol (dCRTP) feature.

For complete conceptual information, see the section "Distributed Compressed Real-Time Protocol" in the chapter "Link Efficiency Mechanisms Overview" in this book.

For a complete description of the dCRTP commands in this chapter, refer to the Cisco IOS IP Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.

To identify the hardware platform or software image information associated with a feature, use the Feature Navigator on Cisco.com to search for information about the feature or refer to the software release notes for a specific release. For more information, see the "Identifying Supported Platforms" section in the "Using Cisco IOS Software" chapter in this book.

Distributed CRTP Configuration Task List

The dCRTP feature is enabled automatically. You can configure the dCRTP feature by changing the number of header compression connections, an optional procedure. To configure the Distributed CRTP feature, complete the task in the following section:

•Changing the Number of Header Compression Connections (Optional)

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Note The instructions in this section assume that Real-Time Protocol (RTP) or TCP header compression is already enabled. For information on configuring RTP header compression, see the chapter "Configuring Compressed Real-Time Protocol" in this book. For information on configuring TCP header compression, refer to the Cisco IOS IP Configuration Guide.

If TCP or RTP header compression is enabled, the header compression is performed in the distributed Cisco Express Forwarding (CEF)-switched or distributed fast-switched path automatically. No additional configuration tasks are required.

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See the end of this chapter for the section "Distributed CRTP Configuration Examples."

Changing the Number of Header Compression Connections

By default, for Frame Relay encapsulation, there can be 256 TCP header compression connections and 256 RTP header compression connections (128 calls for each type). The maximum value is fixed, not configurable.

By default, for PPP or High-Level Data Link Control (HDLC) encapsulation, the software allows 32 TCP header compression connections (16 calls). This default can be increased to a maximum of 256 TCP header compression connections. The Cisco IOS software also allows 32 RTP header compression connections (16 calls). This default can be increased to a maximum of 1000 RTP header compression connections on an interface.

To change the number of compression connections supported, use the following commands in interface configuration mode, as needed:

Command	Purpose
Router(config-if)# ip tcp compression-connections number	Specifies the total number of TCP header compression connections supported on the interface.
Router(config-if)# ip rtp compression-connections number	Specifies the total number of RTP header compression connections supported on the interface.

Distributed CRTP Configuration Examples

The following sections provide dCRTP configuration examples:

•Distributed Compressed RTP Header Compression Example

•Express TCP Header Compression Example

For information on how to configure the dCRTP feature, see the section "Distributed CRTP Configuration Task List" in this chapter.

Distributed Compressed RTP Header Compression Example

The following example shows the output of the show ip rtp header command when a Cisco 7500 router with a Versatile Interface Processor (VIP) has the dCRTP feature enabled. When the dCRTP feature is disabled, the distributed fast-switched line of the output, which is in italics for emphasis, does not appear.

Router# show ip rtp header

RTP/UDP/IP header compression statistics:

   Interface Serial4/1/1:

   Distributed fast switched:

   8 seconds since line card sent last stats update

     Rcvd:   0 total, 0 compressed, 0 errors

              0 dropped, 0 buffer copies, 0 buffer failures

     Sent:   0 total, 0 compressed, 

              0 bytes saved, 0 bytes sent

     Connect:16 rx slots, 16 tx slots, 

              0 long searches, 0 misses 0 collisions

Express TCP Header Compression Example

The following example shows the output of the show ip tcp header command when a Cisco 7500 router with a VIP has the dCRTP feature enabled. When the dCRTP feature is disabled, the distributed fast-switched line of output, which is in italics for emphasis, does not appear.

Router# show ip tcp header

TCP header compression statistics:

   Interface Serial4/1/1:

   Distributed fast switched:  
     8 seconds since line card sent last stats update

     Rcvd:   0 total, 0 compressed, 0 errors

              0 dropped, 0 buffer copies, 0 buffer failures

     Sent:   0 total, 0 compressed, 

              0 bytes saved, 0 bytes sent

     Connect:16 rx slots, 16 tx slots, 

0 long searches, 0 misses 0 collisions