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Header compression is a mechanism that compresses the IP header in a packet before the packet is transmitted. Header compression reduces network overhead and speeds up the transmission of either Real-Time Transport Protocol (RTP) or Transmission Control Protocol (TCP) packets.
One method of configuring header compression on your network is to use an IP header compression (IPHC) profile. An IPHC profile is a kind of template within which you can configure the type of header compression that you want to use, set all of the optional features and parameters for header compression, and then apply the profile to an interface, subinterface, or Frame Relay permanent virtual circuit (PVC).
This module describes the concepts and tasks for configuring header compression using IPHC profiles.
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring Header Compression Using IPHC Profiles" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
•Prerequisites for Using IPHC Profiles
•Restrictions for Using IPHC Profiles
•Information About Using IPHC Profiles
•How to Configure Header Compression Using IPHC Profiles
•Configuration Examples for Using IPHC Profiles
•Feature Information for Configuring Header Compression Using IPHC Profiles
Before using IPHC profiles to configure header compression, read the information in the "Header Compression" module.
IPHC profiles are not supported on L2TP networks.
•Benefits of Using IPHC Profiles
•Configurable Header Compression Features and Settings
•Tasks for Using IPHC Profiles
An IPHC profile provides a flexible means of enabling header compression and the options associated with header compression. For example, header compression (and the header compression options) can be enabled once in an IPHC profile, and then the IPHC profile can be applied to one or more of the following:
•An interface
•A subinterface
•A Frame Relay PVC
You use the iphc-profile command to create the IPHC profile. When you create an IPHC profile, you must specify the IPHC profile type. The IPHC profile choices are Internet Engineering Task Force (IETF) or van-jacobson. You specify the IPHC profile type with the ietf keyword or the van-jacobson keyword of the iphc-profile command.
The ietf profile type conforms with and supports the standards established with RFC 2507, RFC 2508, RFC 3544, and RFC 3545 and is typically associated with non-TCP header compression (for example, RTP header compression). The van-jacobson profile type conforms with and supports the standards established with RFC 1144 and is typically associated with TCP header compression.
Considerations When Specifying the IPHC Profile Type
When specifying the IPHC profile type, consider whether you are compressing TCP traffic or non-TCP (that is, RTP) traffic. Also consider the header compression format capabilities of the remote network link to which you will be sending traffic.
The IPHC profile type that you specify directly affects the header compression format used on the remote network links to which the IPHC profile is applied. Only TCP traffic is compressed on remote network links using a van-jacobson IPHC profile, whereas both TCP and non-TCP (for example, RTP) traffic is compressed on remote network links using an ietf IPHC profile.
Note The header compression format in use on the router that you are configuring and the header compression format in use on the remote network link must match.
The specific header compression features and settings that you can configure (that is, enable or modify) are determined by the IPHC profile type that you select (either van-jacobson or ietf) when you create the IPHC profile. There is one set of features and options for the van-jacobson IPHC profile type and another set for the ietf IPHC profile type. Both sets are listed below.
Features and Settings for van-jacobson IPHC Profile Type Header Compression
If you specify van-jacobson as the IPHC profile type, you can enable TCP header compression and set the number of TCP contexts. Table 1 lists the van-jacobson IPHC profile type header compression features and settings that are available and the command used to enable that feature or setting.
Features and Settings for ietf IPHC Profile Type Header Compression
If you specify ietf as the IPHC profile type, you can enable non-TCP header compression (that is, RTP header compression), along with a number of additional features and settings. Table 2 lists the ietf IPHC profile type header compression features and settings that are available and the command used to enable that feature or setting.
The tasks for configuring header compression using an IPHC profile are described below.
1. Create the IPHC profile and specify the IPHC profile type (ietf or van-jacobson) that you want to use.
2. Enable or set the header compression features available for the IPHC profile type that you specified when you created the IPHC profile. The header compression features vary by IPHC profile type.
3. Attach the IPHC profile to an interface, subinterface, or Frame Relay PVC.
4. Display information about the IPHC profiles that you have created.
Figure 1 illustrates the high-level processes for configuring header compression using IPHC profiles.
Figure 1 Flowchart for Configuring Header Compression Using IPHC Profiles
•Creating an IPHC Profile (required)
•Enabling the Options for van-jacobson IPHC Profile Type Header Compression (required)
or
Enabling the Options for ietf IPHC Profile Type Header Compression (required)
•Attaching the IPHC Profile (required)
•Displaying the IPHC Profile Statistics (optional)
The first task is to create an IPHC profile. When you create an IPHC profile, you can create either an ietf IPHC profile or a van-jacobson IPHC profile, by using the corresponding keyword of the iphc-profile command.
To create either an ietf IPHC profile or a van-jacobson IPHC profile, complete the following steps.
Before completing the steps listed below, determine the type of IPHC profile that you want to create: ietf or van-jacobson. The IPHC profile type that you create directly affects the header compression options available for you.
For more information about IPHC profile types and considerations for selecting one or the other, see the "IPHC Profile Types" section.
The IPHC profile name must be unique and cannot be longer than 32 characters. IPHC profile names exceeding this maximum are truncated to 32 characters.
1. enable
2. configure terminal
3. iphc-profile profile-name {ietf | van-jacobson}
4. end
So far you have created either an ietf IPHC profile or a van-jacobson IPHC profile.
The next step is to enable or set any additional header compression features or options available for the type of IPHC profile that you created.
Choose one of the following:
•To enable or set any of the header compression features available for a van-jacobson IPHC profile, complete the steps in the "Enabling the Options for van-jacobson IPHC Profile Type Header Compression" section below.
•To enable or set any of the header compression features available for an ietf IPHC profile, complete the steps in the "Enabling the Options for ietf IPHC Profile Type Header Compression" section.
If you created a van-jacobson IPHC profile, you can enable TCP header compression and set the number of TCP contexts.
Note If you created an ietf IPHC profile, the header compression options available to you are documented in the "Enabling the Options for ietf IPHC Profile Type Header Compression" section.
To enable TCP header compression set the number of TCP contexts, complete the following steps.
The IPHC profile must exist.
1. enable
2. configure terminal
3. iphc-profile profile-name
4. tcp
5. tcp contexts {absolute number-of-contexts | kbps-per-context kbps}
6. end
The next step is to attach the IPHC profile to an interface, a subinterface, or a Frame Relay PVC. For the instructions to follow, see the "Attaching the IPHC Profile" section.
Note If you created a van-jacobson IPHC profile, complete the tasks in the "Enabling the Options for van-jacobson IPHC Profile Type Header Compression" section.
If you created an ietf IPHC profile, you can enable or set a variety of header compression options. These options include enabling non-TCP header compression, enabling RTP header compression, and enabling ECRTP. For a list of the additional header compression features or settings available with an ietf IPHC profile, see the "Features and Settings for ietf IPHC Profile Type Header Compression" section.
The IPHC profile must exist.
1. enable
2. configure terminal
3. iphc-profile profile-name
4. non-tcp
5. non-tcp contexts {absolute number-of-contexts | kbps-per-context kbps}
6. rtp
7. recoverable-loss {dynamic | packet-drops}
8. refresh max-period {number-of-packets | infinite}
9. refresh max-time {length-of-time | infinite}
10. refresh rtp
11. feedback
12. maximum header max-header-size
13. tcp
14. tcp contexts {absolute number-of-contexts | kbps-per-context kbps}
15. end
You can attach the IPHC profile (either an ietf IPHC profile or a van-jacobson IPHC profile) to an interface, a subinterface, or a Frame Relay PVC.
Choose one of the following:
•To attach the IPHC profile to an interface or subinterface, complete the steps in the "Attaching an IPHC Profile to an Interface" section below.
•To attach the IPHC profile to a Frame Relay PVC, complete the steps in the "Attaching an IPHC Profile to a Frame Relay PVC" section.
To attach an IPHC profile to an interface or subinterface, complete the following steps.
•The IPHC profile must exist.
•IP must be enabled on the interface or subinterface.
•The type of encapsulation in use on the interface or subinterface must support header compression. Two types of encapsulation that typically support header compression are PPP and HDLC encapsulation.
•Header compression must not already be enabled.
•The interface or subinterface must have sufficient memory.
1. enable
2. configure terminal
3. interface type number [name-tag]
4. iphc-profile profile-name
5. end
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Step 1 |
enable Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type number [name-tag] Router(config)# interface fastethernet0 |
Configures an interface type and enters interface configuration mode. •Enter the interface type and the interface number. |
Step 4 |
iphc-profile profile-name Router(config-if)# iphc-profile profile1 |
Attaches the IPHC profile to the interface. •Enter the IPHC profile to be attached to the interface specified in Step 3. |
Step 5 |
end Router(config-if)# end |
(Optional) Exits IPHC-profile configuration mode. |
To attach an IPHC profile to a Frame Relay PVC, complete the following steps.
•The IPHC profile must exist.
•On a network that is using Frame Relay encapsulation, IPHC profiles are supported only in the Frame Relay map-class infrastructure.
1. enable
2. configure terminal
3. map-class frame-relay map-class-name
4. frame-relay iphc-profile profile-name
5. exit
6. interface type number [name-tag]
7. encapsulation frame-relay
8. ip address ip-address mask
9. frame-relay interface-dlci dlci
10. class name
11. end
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---|---|---|
Step 1 |
enable Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal Router# configure terminal |
Enters global configuration mode. |
Step 3 |
map-class frame-relay map-class-name Router(config)# map-class frame-relay mapclass1 |
Creates a map class and enters static map class configuration mode. •Enter the Frame Relay map class name. |
Step 4 |
frame-relay iphc-profile profile-name Router(config-map-class)# frame-relay iphc-profile profile2 |
Attaches the IPHC profile to the Frame Relay map class. •Enter the IPHC profile to be attached to the Frame Relay map class created in Step 3. |
Step 5 |
exit Router(config-map-class)# exit |
Exits static map class configuration mode. |
Step 6 |
interface type number [name-tag] Router(config)# interface serial2/0 |
Configures an interface type and enters interface configuration mode. •Enter the interface type and the interface number. |
Step 7 |
encapsulation frame-relay Router(config-if)# encapsulation frame-relay |
Enables Frame Relay encapsulation on the interface. |
Step 8 |
ip address ip-address mask Router(config-if)# ip address 209.165.200.225 255.255.255.224 |
Sets a primary IP address for an interface. •Enter the IP address and mask for the associated IP subnet. |
Step 9 |
frame-relay interface-dlci dlci Router(config-if)# frame-relay interface-dlci 100 |
Assigns a data-link connection identifier (DLCI) to a specified Frame Relay interface on the router or access server and enters Frame Relay DLCI configuration mode. •Enter the DLCI number to be used on the specified interface. |
Step 10 |
class name Router(config-fr-dlci)# class mapclass1 |
Associates a map class with a specified DLCI. •Enter the name of the map class to associate with the specified DLCI. |
Step 11 |
end Router(config-fr-dlci)# end |
(Optional) Exits Frame Relay DLCI configuration mode. |
In this task, you can display statistical information about the IPHC profiles that you have created and configured. Displaying the IPHC profile statistics allows you to confirm that the IPHC profile is configured as you intended.
Information reported includes the IPHC profile name and profile type, the type of header compression enabled, whether any optional header compression features (such as the number of contexts) are enabled, and the name of the interface to which the IPHC profile is attached (if applicable).
To display the IPHC profile statistics, complete the following steps.
The IPHC profile must exist.
1. enable
2. show iphc-profile [profile-name]
3. end
This section provides the following configuration examples:
•Example: Creating an IPHC Profile
•Example: Enabling TCP Header Compression
•Example: Enabling Non-TCP Header Compression
•Example: Attaching the IPHC Profile
•Example: Reporting IPHC Profile Statistics
In the following example, a van-jacobson IPHC profile called profile1 has been created.
Router> enable
Router# configure terminal
Router(config)# iphc-profile profile1 van-jacobson
Router(config-iphcp)# end
In the following example, an ietf IPHC profile called profile2 has been created.
Router> enable
Router# configure terminal
Router(config)# iphc-profile profile2 ietf
Router(config-iphcp)# end
In the following example, TCP header compression has been enabled in a van-jacobson IPHC profile called profile1. Additionally, the number of TCP contexts has been set to 25.
Router> enable
Router# configure terminal
Router(config)# iphc-profile profile1
Router(config-iphcp)# tcp
Router(config-iphcp)# tcp contexts absolute 25
Router(config-iphcp)# end
In the following example, RTP header compression has been enabled in an ietf IPHC profile called profile2. Additionally, ECRTP has been enabled with the recoverable-loss command, and the size of the compressed IP header has been set to 75 bytes.
Router> enable
Router# configure terminal
Router(config)# iphc-profile profile2
Router(config-iphcp)# rtp
Router(config-iphcp)# recoverable-loss 5
Router(config-iphcp)# maximum header 75
Router(config-iphcp)# end
In the following example, an IPHC profile called profile1 is attached to serial interface 0.
Router> enable
Router# configure terminal
Router(config)# interface serial0
Router(config-if)# iphc-profile profile1
Router(config-if)# end
In the following example, an IPHC profile called profile2 is attached to a Frame Relay map class called mapclass1.
Router> enable
Router# configure terminal
Router(config)# map-class frame-relay mapclass1
Router(config-map-class)# frame-relay iphc-profile profile2
Router(config-map-class)# exit
Router(config)# interface serial2/0
Router(config-if)# encapsulation frame-relay
Router(config-if)# ip address 209.165.200.225 255.255.255.224
Router(config-if)# frame-relay interface-dlci 100
Router(config-fr-dlci)# class mapclass1
Router(config-fr-dlci)# end
The following is sample output from the show iphc-profile command. In this output, information about two IPHC profiles, profile21 and 20, is displayed.
Router# show iphc-profile
IPHC Profile "profile21"
Type: VJ
Compressing: TCP
Contexts : TCP fixed at 150
Controlled interfaces: (1)
Se3/1
IPHC Profile "profile20"
Type: IETF
Compressing: TCP NON-TCP (RTP)
Contexts : TCP 1 for each 0 kbits NON-TCP 1 for each 0 kbits
Refresh : NON-TCP and RTP every 5 seconds or 256 packets
Controlled interfaces: (1)
Se3/0
The following sections provide references related to IPHC profiles.
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Cisco IOS commands |
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QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
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QoS functionality overview |
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Header compression overview |
"Header Compression" module |
RTP header compression |
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TCP header compression |
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Class-based RTP and TCP header compression |
"Configuring Class-Based RTP and TCP Header Compression" module |
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No new or modified standards are supported, and support for existing standards has not been modified. |
— |
Table 3 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 3 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
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IPHC Profiles |
12.4(9)T |
The IPHC Profiles feature allows you to configure header compression in a kind of template ("profile") and to apply the profile to interfaces, subinterfaces, or Frame Relay PVCs. The following sections provide information about this feature: •Information About Using IPHC Profiles •How to Configure Header Compression Using IPHC Profiles The following commands were introduced by this feature: feedback, iphc-profile, maximum header, non-tcp, non-tcp contexts, recoverable-loss, refresh max-period, refresh max-time, refresh rtp, rtp, show iphc-profile, tcp, tcp contexts. |