IP Header Compression
This chapter
provides information on configuring an enhanced, or extended, service.
The product administration guides provide examples and procedures
for configuration of basic services on the system. It is recommended
that you select the configuration example that best meets your service
model, and configure the required elements for that model, as described
in the respective product administration guide, before using the
procedures in this chapter.
IMPORTANT:
RoHC header compression
is not applicable for SGSN and GGSN services.
This chapter includes
the following procedures:
Overview
The system supports
IP header compression on the PPP tunnels established over the EVDO-RevA
A10 links and also over the GRE tunnel that is connected to the PCF
to support EVDO-RevA Service Option 67 (SO67).
By default IP header
compression using the VJ algorithm is enabled for subscribers using PPP.
Note that you can
use the default VJ header compression algorithm alone, configure
the use of RoHC header compression only, or use both VJ and RoHC
IP header compression.
- Van Jacobsen (VJ)
- The RFC 1144 (CTCP) header compression standard was developed
by V. Jacobson in 1990. It is commonly known as VJ compression.
It describes a basic method for compressing the headers of IPv4/TCP
packets to improve performance over low speed serial links.
- RObust Header Compression
(RoHC) - The RFC 3095 (RoHC) standard was developed in 2001.
This standard can compress IP/UDP/RTP headers
to just over one byte, even in the presence of severe channel impairments.
This compression scheme can also compress IP/UDP and IP/ESP
packet flows. RoHC is intended for use in wireless radio network
equipment and mobile terminals to decrease header overhead, reduce
packet loss, improve interactive response, and increase security
over low-speed, noisy wireless links.
IMPORTANT:
The RoHC is a licensed
Cisco feature. A separate feature license may be required. Contact your
Cisco account representative for detailed information on specific
licensing requirements. For information on installing and verifying
licenses, refer to the Managing
License Keys section of the Software Management
Operations chapter in the System Administration Guide.
In addition, you can
configure RoHC profiles that define RoHC Compressor and Decompressor
parameters. These RoHC profiles can be applied to subscribers.
You can also turn
off all IP header compression for a subscriber.
The procedures in
this chapter describe how to configure the IP header compression methods
used, but for RoHC over PPP the Internet Protocol Control Protocol
(IPCP) negotiations determine when they are used.
Implementing IP header
compression provides the following benefits:
- Improves interactive
response time
- Allows the use of
small packets for bulk data with good line efficiency
- Allows the use of
small packets for delay sensitive low data-rate traffic
- Decreases header overhead.
- Reduces packet loss
rate over lossy links.
Configuring VJ
Header Compression for PPP
By default,
VJ IP header compression is enabled for subscriber sessions. When
VJ header compression is configured all IP headers are compressed
using the VJ compression algorithm.
Note that procedure
described in this section is applicable only when VJ header compression
is disabled.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for header
compression. For more information on commands that configure additional
parameters and options, refer Subscriber Configuration
Mode Commands chapter in Command
Line Interface Reference .
To configure the system
to enable VJ header compression to IP headers:
-
Enable VJ header
compression by applying the example configuration in the Enabling VJ Header
Compression section.
-
Verify your VJ header
compression configuration by following the steps in the Verifying the VJ Header
Compression Configuration section.
-
Save your configuration
to flash memory, an external memory device, and/or a network
location using the Exec mode command save configuration.
For additional information on how to verify and save configuration
files, refer to the System
Administration Guide and the Command Line Interface
Reference.
Enabling VJ Header
Compression
Use the following
example to enable the VJ header compression over PPP:
configure
context <ctxt_name>
subscriber
name <subs_name>
ip
header-compression vj
end
Notes:
- <ctxt_name>
is the system context in which you wish to configure the subscriber
profile. Typically this is an AAA context.
- <subs_name>
is the name of the subscriber in the current context that you want
to enable VJ IP header compression for.
Verifying the VJ
Header Compression Configuration
These instructions
are used to verify the VJ header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show subscriber configuration
username subs_name
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Configuring RoHC
Header Compression for PPP
RoHC IP header
compression can be configured for all IP traffic, uplink traffic
only, or downlink traffic only. When RoHC is configured for all
traffic, you can specify the mode in which RoHC is applied.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for
header compression. For more information on commands that configure
additional parameters and options, refer Subscriber Configuration
Mode Commands chapter in the Command Line Interface
Reference.
To configure the system
to enable RoHC header compression to IP headers:
- Enable RoHC header compression
by applying the example configuration in the Enabling RoHC Header
Compression for PPP section.
- Verify your RoHC header
compression configuration by following the steps in the Verifying the Header
Compression Configuration section.
- Save your configuration
to flash memory, an external memory device, and/or a network location
using the Exec mode command save configuration. For
additional information on how to verify and save configuration files,
refer to the System Administration
Guide and the Command
Line Interface Reference.
Enabling RoHC Header
Compression for PPP
Use the following
example to enable the RoHC over PPP:
configure
context <ctxt_name>
subscriber
name <subs_name>
ip
header-compression RoHC [ any [ mode { optimistic | reliable | unidirectional } ] | cid-mode { { large | small } [ marked-flows-only | max-cid | max-hdr
<value> | mrru <value> ] } | marked
flows-only | max-hdr <value> | mrru
<value> | downlink | uplink ] }+
end
Notes:
- <ctxt_name>
is the system context in which you wish to configure the subscriber
profile. Typically this is an AAA context.
- <subs_name>
is the name of the subscriber in the current context that you want
to enable RoHC header compression for.
- Refer to the Subscriber Configuration
Mode Commands chapter in Command
Line Interface Reference for more details on this command and
its options.
Verifying the Header
Compression Configuration
These instructions
are used to verify the header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show subscriber configuration
username subs_name
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Configuring Both
RoHC and VJ Header Compression
You can configure
the system to use both VJ and RoHC IP header compression. When both VJ
and RoHC are specified, the optimum header compression algorithm
for the type of data being transferred is used for data in the downlink
direction.
IMPORTANT:
If both RoHC and VJ
header compression are specified, the optimum header compression
algorithm for the type of data being transferred is used for data
in the downlink direction.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for header
compression. For more information on commands that configure additional
parameters and options, refer Subscriber Configuration
Mode Commands chapter in th Command Line Interface Reference.
To configure the system
to enable both RoHC and VJ header compression to IP headers:
- Enable the RoHC and
VJ header compression by applying the example configuration in the Enabling RoHC and
VJ Header Compression for PPP section.
- Verify your RoHC and
VJ header compression configuration by following the steps in the Verifying the Header
Compression Configuration section.
- Save your configuration
to flash memory, an external memory device, and/or a network location
using the Exec mode command save configuration. For
additional information on how to verify and save configuration files,
refer to the System Administration
Guide and the Command
Line Interface Reference.
Enabling RoHC and
VJ Header Compression for PPP
Use the following
example to enable the header compression over PPP:
configure
context <ctxt_name>
subscriber
name <subs_name>
ip
header-compression vj RoHC [ any [ mode { optimistic | reliable | unidirectional } ] | cid-mode { { large | small } [ marked-flows-only | max-cid | max-hdr
<value> | mrru <value> ] } | marked
flows-only | max-hdr <value> | mrru
<value> | downlink | uplink ] }+
end
Notes:
- <ctxt_name>
is the system context in which you wish to configure the subscriber
profile. Typically this is an AAA context.
- <subs_name>
is the name of the subscriber in the current context that you want
to enable RoHC header compression for.
- Refer to the Subscriber
Configuration Mode Commands chapter in Command Line Interface Reference
for more details on this command and its options.
Verifying the Header
Compression Configuration
These instructions
are used to verify the header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show subscriber configuration
username subs_name
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Configuring RoHC
for Use with SO67 in PDSN or HSGW Service
This section
explains how to set RoHC settings in the PDSN or HSGW Service configuration mode.
These settings are transferred to the PCF during the initial A11
setup and are used for the GRE tunnel that is connected to the PCF
to support EVDO-RevA Service Option 67 (SO67). RoHC is enabled through an
auxiliary SO67 A10 connection and the PCF signals this information
when the auxiliary A10 is connected.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for
header compression. For more information on commands that configure
additional parameters and options, refer PDSN Service Configuration
Mode Commands or HSGW Service
Configuration Mode Commands chapter in Command Line Interface Reference.
To configure the system
to enable the RoHC header compression feature at the PDSN or HSGW
Service over SO67:
-
Enable header compression
by applying the example configuration in the Enabling ROHC Header
Compression with PDSN or Enabling ROHC Header Compression
with HSGW section.
-
Verify your RoHC
configuration by following the steps in the Verifying the Header
Compression Configuration section.
-
Save your configuration
to flash memory, an external memory device, and/or a network
location using the Exec mode command save configuration.
For additional information on how to verify and save configuration
files, refer to the System
Administration Guide and the Command Line Interface
Reference.
Enabling RoHC Header
Compression with PDSN
Use the following
example to enable the RoHC header compression with PDSN over SO67:
configure
context <ctxt_name>
pdsn-service <svc_name>
ip
header-compression rohc
cid-mode {large | small} max-cid integer
mrru <num_octets>
profile { [esp-ip] [rtp-udp] [udp-ip] [uncompressed-ip] }
end
Notes:
- <ctxt_name>
is the system context in which PDSN service is configured and you
wish to configure the service profile.
- <svc_name>
is the name of the PDSN service in which you want to enable RoHC
over SO67.
- Refer to the PDSN Service RoHC Configuration
Mode Commands chapter in Command
Line Interface Reference for more details on this command and
its options.
Enabling RoHC Header
Compression with HSGW
Use the following
example to enable the RoHC header compression with HSGW over SO67:
configure
context <ctxt_name>
hsgw-service <svc_name>
ip
header-compression rohc
cid-mode {large | small} max-cid integer
mrru <num_octets>
profile { [esp-ip] [rtp-udp] [udp-ip] [uncompressed-ip] }
end
Notes:
- <ctxt_name>
is the system context in which HSGW service is configured and you
wish to configure the service profile.
- <svc_name>
is the name of the HSGW service in which you want to enable RoHC
over SO67.
- Refer to the HSGW Service RoHC Configuration
Mode Commands chapter in Command
Line Interface Reference for more details on this command and
its options.
Verifying the Header
Compression Configuration
These instructions
are used to verify the header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show configuration
context ctxt_name
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Using an RoHC Profile
for Subscriber Sessions
You can configure
RoHC profiles that specify numerous compressor and decompressor
settings. These profiles can in turn be applied to a specific subscriber
or the default subscriber. RoHC profiles are used for both RoHC
over PPP and for RoHC over SO67.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for
header compression. For more information on commands that configure
additional parameters and options, refer Subscriber Configuration
Mode Commands chapter in Command
Line Interface Reference.
To configure the system
to apply RoHC profile to a subscriber session:
-
Create RoHC profile
using decompression mode or decompression mode. If you want to use
compression mode go to step a else follow step b:
-
Configure RoHC profile
by applying the example configuration in the Creating ROHC Profile
for Subscriber using Compression Mode section using compression
mode.
-
Alternatively configure
RoHC profile by applying the example configuration in the Creating ROHC Profile
for Subscriber using Decompression Mode section using compression
mode.
-
Apply existing RoHC
profile to a subscriber by applying the example configuration in
the Applying ROHC Profile
to a Subscriber section.
-
Verify your RoHC
header compression configuration by following the steps in the Verifying the Header
Compression Configuration section.
-
Save your configuration
to flash memory, an external memory device, and/or a network
location using the Exec mode command save configuration.
For additional information on how to verify and save configuration
files, refer to the System
Administration Guide and the Command Line Interface
Reference.
Creating RoHC Profile
for Subscriber using Compression Mode
Use the following
example to create RoHC profile for a subscriber using compression mode:
configure
RoHC-profile
profile-name <RoHC_comp_profile_name>
decompression-options
[no] multiple-ts-stride
rtp-sn-p <p_value>
[no] use-ipid-override
[no] use-optimized-talkspurt
[no] use-optimized-transience
[no] use-timer-based-compression
end
Notes:
- <RoHC_comp_profile_name>
is the name of the RoHC profile with compression mode which you
want to apply to a subscriber.
- System configured
most of the parameters by default. For more information on other options
and parameters and details, refer to the RoHC Profile Compression
Configuration Mode Commands chapter in Command Line Interface Reference.
Creating RoHC Profile
for Subscriber using Decompression Mode
Use the following
example to create RoHC profile for a subscriber using decompression mode:
configure
RoHC-profile
profile-name <RoHC_decomp_profile_name>
decompression-options
context-timeout <dur>
max-jitter-cd <dur_ms>
nak-limit <limit>
optimistic-mode-ack
optimistic-mode-ack-limit <num_pkts>
piggyback-wait-time <dur_ms>
preferred-feedback-mode { bidirectional-optimistic | bidirectional-reliable | unidirectional }
rtp-sn-p <p_value>
[no] rtp-sn-p-override
[no] use-clock-option
[no] use-crc-option
[no] use-feedback
[no] use-jitter-option
[no] use-reject-option
[no] use-sn-option
end
Notes:
- <RoHC_profile_name>
is the name of the RoHC profile with decompression mode which you
want to apply to a subscriber.
- System configured
most of the parameters by default. For more information on other options
and parameters and details, refer to the RoHC Profile Decompression
Configuration Mode Commands chapter in Command Line Interface Reference.
Applying RoHC Profile
to a Subscriber
Once an RoHC
profile has been created that profile can be specified to be used
for a specific subscribers. Use the following example to apply the
RoHC profile to a subscriber:
configure
context <ctxt_name>
subscriber
name <subs_name>
RoHC-profile-name <RoHC_profile_name>
end
Notes:
- <ctxt_name>
is the system context in which you wish to configure the subscriber
profile. Typically this is an AAA context.
- <subs_name>
is the name of the subscriber in the current context that you want
to enable RoHC header compression for.
- <RoHC_profile_name>
is the name of the existing RoHC profile (created with compressed
or decompressed mode) which you want to apply to a subscriber in
the current context.
- Refer to the Subscriber Configuration
Mode Commands chapter in Command
Line Interface Reference for more details on this command and
its options.
Verifying the Header
Compression Configuration
These instructions
are used to verify the header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show subscriber configuration
username subs_name
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Disabling VJ Header
Compression Over PPP
By default,
VJ IP header compression is enabled for subscriber sessions. When
VJ header compression is configured all IP headers are compressed
using the VJ compression algorithm.
If you do not want
to apply compression to any IP headers for a subscriber session
you can disable the IP header compression feature.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for header
compression. For more information on commands that configure additional
parameters and options, refer Subscriber Configuration
Mode Commands chapter in Command
Line Interface Reference.
To configure the system
to disable VJ header compression to IP headers:
-
Disable header compression
by appling the example configuration in the Disabling VJ Header
Compression section.
-
Verify your VJ header
compression configuration by following the steps in the Verifying the VJ Header
Compression Configuration section.
-
Save your configuration
to flash memory, an external memory device, and/or a network
location using the Exec mode command save configuration.
For additional information on how to verify and save configuration
files, refer to the System
Administration Guide and the Command Line Interface
Reference.
Disabling VJ Header
Compression
Use the following
example to disable the VJ header compression over PPP:
configure
context <ctxt_name>
subscriber
name <subs_name>
no
ip header-compression
end
Notes:
- <ctxt_name>
is the system context in which you wish to configure the subscriber
profile. Typically this is an AAA context.
- <subs_name>
is the name of the subscriber in the current context that you want
to disable IP header compression for.
Verifying the VJ
Header Compression Configuration
These instructions
are used to verify the VJ header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show subscriber configuration username <subs_name>
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Disabling RoHC
Header Compression Over SO67
If you do not
want to apply compression to any IP headers for a subscriber sessions
using the EVDO-RevA SO67 feature, you can disable the IP header
compression feature at the PDSN or HSGW Service.
IMPORTANT:
This section provides
the minimum instruction set for configuring subscriber profile for
header compression. For more information on commands that configure
additional parameters and options, refer PDSN Service Configuration
Mode Commands or HSGW Service
Configuration Mode Commands chapter in Command Line Interface Reference.
To configure the system
to disable the IP header compression feature at the PDSN or HSGW Service:
-
Disable header compression
by applying the example configuration in the Disabling ROHC Header
Compression section.
-
Verify your RoHC
configuration by following the steps in the Verifying the Header
Compression Configuration section.
-
Save your configuration
to flash memory, an external memory device, and/or a network
location using the Exec mode command save configuration.
For additional information on how to verify and save configuration
files, refer to the System
Administration Guide and the Command Line Interface
Reference.
Disabling RoHC
Header Compression
Use the following
example to disable the header compression over SO67:
configure
context <ctxt_name>
pdsn/hsgw-service <svc_name>
no
ip header-compression RoHC
end
Notes:
- <ctxt_name>
is the system context in which PDSN or HSGW service is configured
and you wish to configure the service profile.
- <svc_name>
is the name of the PDSN or HSGW service in which you want to disable
RoHC over SO67.
Verifying the Header
Compression Configuration
These instructions
are used to verify the header compression configuration.
-
Verify that your
header compression configurations for subscriber by entering the
following command in Exec Mode in specific context:
show configuration
context <ctxt_name>
The
output of this command is a concise listing of subscriber parameter
settings as configured.
Checking IP Header
Compression Statistics
This section
commands to use to retrieve statistics that include IP header compression
information.
The following Exec
mode commands can be used to retrieve IP header compression statistics:
- monitor protocol ppp
- show ppp
- show ppp statistics
- show RoHC statistics
- show RoHC statistics
pdsn-service
- show subscriber full
username
For more information
on these commands, refer to the Command Line Interface Reference.
RADIUS Attributes
for IP Header Compression
This section
lists the names of the RADIUS attributes to use for RoHC header
compression. For more information on these attributes, refer to
the AAA Interface Administration and Reference.
One of the following
attributes can be used to specify the name of the RoHC profile to
use for the subscriber session:
- SN-RoHC-Profile-Name
- SN1-RoHC-Profile-Name
Any RoHC parameters
not specified in the RoHC profile are set to their default values.