Cisco 3825 - Manual (Page 177)

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Cisco 3825 Mobile Wireless Edge Router Software Configuration Guide
OL-15667-03
Appendix A Cisco 3825 Mobile Wireless Edge Router RAN-O Command Reference
ip tcp header-compression
Header Compression passive Keyword
By default, the ip tcp header-compression command compresses outgoing TCP traffic. This command
includes an optional passive keyword. If you specify the passive keyword, outgoing TCP traffic is
compressed only if incoming TCP traffic on the same interface is compressed. If you do not specify the
passive keyword, all TCP traffic is compressed.
For PPP interfaces, the passive keyword is ignored. PPP interfaces negotiate the use of
header-compression, regardless of whether the passive keyword is specified. Therefore, on PPP
interfaces, the passive keyword is replaced by IPHC format, the default format for PPP interfaces.
Header Compression iphc-format Keyword
This command includes the iphc-format keyword. The iphc-format keyword indicates the type of
header compression that will be used. For PPP and HDLC interfaces, when the iphc-format keyword is
specified, Rapid Transport Protocol (RTP) header-compression is also enabled. For this reason, the ip
rtp header-compression command appears in the output of the show running-config command.
Because both TCP and RTP header compression are enabled, both TCP and UDP packets are
compressed.
Note For Frame Relay interfaces, the iphc-format keyword is not available.
Header Compression ietf-format Keyword
This command includes the ietf-format keyword. The ietf-format keyword indicates the type of header
compression that will be used. For HDLC interfaces, the ietf-format compresses only TCP packets. For
PPP interfaces, when the ietf-format keyword is specified, RTP header-compression is also enabled. For
this reason, the ip rtp header-compression command appears in the output of the show running-config
command. Because both TCP and RTP header compression are enabled, both TCP and UDP packets are
compressed.
Note For Frame Relay interfaces, the ietf-format keyword is not available.
Examples The following example sets the first serial interface for header compression with a maximum of ten
cache entries:
Router(config)# interface serial 0
Router(config-if)# ip tcp header-compression
Router(config-if)# ip tcp compression-connections 10
The following example enables RTP header compression on the Serial1/0/0.0 subinterface and limits the
number of RTP header compression connections to 10. In this example, the optional iphc-format
keyword of the ip tcp header-compression command is specified:
Router(config)# interface serial1/0/0.0
Router(config-if)# encapsulation ppp
Router(config-if)# ip tcp header-compression iphc-format
Router(config-if)# ip tcp compression-connections 10
The following example enables RTP header compression on the Serial1/0/0.0 subinterface and limits the
number of RTP header compression connections to 20. In this example, the optional ietf-format
keyword of the ip tcp header-compression command is specified:
Router(config)# interface serial1/0/0.0
Router(config-if)# ip tcp header-compression ietf-format
Router(config-if)# ip tcp compression-connections 20