# RoHC Profile Decompression Configuration Mode Commands

The RoHC Profile Decompression Configuration Mode is used to configure RoHC (Robust Header Compression) Decompressor parameters.

IMPORTANT:

The availability of commands, keywords and variables in this mode are dependent on platform type, product version, and installed license(s).
accept-delayed-pkts

Accepts delayed packets
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default ] accept-delayed-pkts

default

Returns the command to its default value of disabled.
Usage:

This command helps reduce packet loss during context repair.
Example:
Use the following command to enable the system to accept delayed packets:

    accept-delayed-pkts

context-timeout

Ensures that no expired contexts are used for data compression.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    context-timeout secondsdefault context-timeout

default

Returns the command to its default value.
seconds

Specifies the context timeout value (in seconds) as an integer from 0 through 100.

Default: 20
Usage:

The RoHC stack should periodically clean up expired contexts and release memory in case there is no data activity for the call on this context. The context cleanup period is internally calculated to be set to half of the value of the context-timeout value. This will ensure that no expired contexts are used for data compression.
Example:
The following command sets the context-timeout parameter to 30 seconds:

    context-timeout 30

crc-errors-fo

Sets the limits for when a NACK message is sent while in the FO (First Order) state. A NACK is sent whenever CRC errors are detected within a specified number of packets.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    crc-errors-fo-k num_errorscrc-errors-fo-n num_packts default crc-errors-fo-kdefault crc-errors-fo-n

default

Returns the command to its default value.
crc-errors-fo-k num_errors

Specifies the number of received packets that trigger the sending of a NACK as an integer from 1 through 10.

Default: 1

IMPORTANT:

num_errors must be less than or equal to the value specified with the crc-errors-fo-n command.
crc-errors-fo-n num_packts

Specifies the number of packets to check for CRC errors as an integer from 1 through 10.

Default: 1
Usage:

Use this command to set the parameters that trigger sending a NACK message when in the FO state.
Example:
To configure a NACK to be sent when 4 out of the last 10 packets have CRC errors when in the FO state, use the following commands:

    crc-errors-fo-k 4

    crc-errors-fo-n 10

crc-errors-so

Sets the limits for when a NACK message is sent while in the SO (Second Order) state. A NACK is sent whenever CRC errors are detected within a specified number of packets.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    crc-errors-so-k num_errorscrc-errors-so-n num_packetsdefault crc-errors-so-kdefault crc-errors-so-n

default

Returns the command to its default value.
crc-errors-so-k num_errors

Specifies the number of received packets that trigger the sending of a NACK as an integer from 0 through 10.

Default: 1

IMPORTANT:

num_errors must be less than or equal to the value specified with the crc-errors-so-n command.
crc-errors-so-n num_packets

Specifies the number of packets to check for CRC errors as an integer from 1 through 10.

Default: 1
Usage:

Use this command to set the parameters that trigger sending a NACK message when in the SO state.
Example:
To configure a NACK to be sent when 4 out of the last 10 packets have CRC errors when in the SO state, use the following commands:

    crc-errors-so-k 4

    crc-errors-so-n 10

end

Exits the current configuration mode and returns to the Exec mode.
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    end

Usage:

Use this command to return to the Exec mode.
exit

Exits the current mode and returns to the parent configuration mode.
Product:

All
Privilege:

Security Administrator, Administrator
Syntax

    exit

Usage:

Use this command to return to the parent configuration mode.
nack-limit

Sets the number of unsuccessful decompressions allowed before a NACK is sent.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    nack-limit limitdefault nack-limit

default

Returns the command to its default value.
limit

Specifies the number of unsuccessful decompressions allowed as an integer from 0 through 20.

Default: 0
Usage:

Use this command to set the maximum number of unsuccessful decompressions before a NACK message is sent.
Example:
The following command sets the number of unsuccessful decompressions allowed to 10:

    nack-limit 10

optimistic-mode-ack

When this command is enabled and a type 2 IR-DYN packet is successfully decompressed, an optional ACK is sent in U-mode.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] optimistic-mode-ack

default

Returns the command to its default value of enabled.
no

Disables the sending of the optional ACK.
Usage:

Use this command to enable and disable the sending of an optional ACK in U-mode when a type 2 IR-DYN packet is successfully decompressed.
Example:
To enable the sending of the optional ACK, enter the following command:

    optimistic-mode-ack

To disable the sending of the optional ACK, enter the following command:

    no optimistic-mode-ack

optimistic-mode-ack-limit

Sets the number of packets for which to send ACKs.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    optimistic-mode-ack-limit num_pktsdefault optimistic-mode-ack-limit

default

Returns the command to its default value.
num_pkts

Specifies the number of packets for which to send ACKs as an integer from 0 through 20.

Default: 3
Usage:

Use this command to set the number of packets to send the optional ACK for when a type 2 IR-DYN packet is successfully decompressed.
Example:
Enter the following command to set the number of packets to send and ACK for to 6:

    optimistic-mode-ack-limit 6

Use the following command to set the number of packets to send an ACK for back to the default of 3:

    default optimistic-mode-ack-limit

piggyback-wait-time

Specifies the time in milliseconds to wait for a feedback packet to be picked up as piggybacked feedback by the associated compressor.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    piggyback-wait-time m_secsdefault piggyback-wait-time

default

Returns the command to its default value.
m_secs

Specifies the time (in milliseconds) to wait for a feedback packet to be picked up as an integer value from 0 through 1000.

Default: 80
Usage:

Use this command to set the time in milliseconds to wait for a feedback packet to be picked up as piggybacked feedback by the associated compressor.
Example:
The following command sets the wait time to 120 ms:

    piggyback-wait-time 120

preferred-feedback-mode

Specifies the preferred feedback mode to use between the compressor and the decompressor
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    preferred-feedback-mode { bidirectional-optimistic | bidirectional-reliable | unidirectional }default preferred-feedback-mode

default

Returns the command to its default setting of bidirectional-optimistic.
bidirectional-optimistic

This mode is similar to the Unidirectional mode, with the exception of a feedback channel used to send error recovery requests from the decompressor to compressor.

This is the default mode.
bidirectional-reliable

Reliable mode makes extensive use of a feedback channel to avoid packet loss from context invalidation. A secure reference model is used instead of the optimistic approach used in the other modes. With the secure reference model, the confidence of the compressor depends on acknowledgements from the decompressor for every context updating packet.

Periodically the compressor sends context updating packets repeatedly until an acknowledgement is received from the decompressor.
unidirectional

Packets are sent in only one direction, from the compressor to the decompressor.
Usage:

Use this command to specify the preferred feedback method to use between the compressor and the decompressor for the current RoHC profile.
Example:
Use the following command to set the preferred feedback mode to bidirectional-reliable:

    preferred-feedback-mode
    bidirectional-reliable

rtp-sn-p

Specifies the value of p in RTP SN (RTP Sequence Number) calculation. Least Significant Bits (LSB) encoding is used for header fields whose values are usually subject to small changes. With LSB encoding, the k least significant bits of the field value are transmitted instead of the original field value, where k is a positive integer. After receiving k bits, the decompressor derives the original value using a previously received value as reference (v_ref). The scheme is guaranteed to be correct if the compressor and the decompressor each use interpretation intervals as follows:

- In which the original value resides
- And in which the original value is the only value that has the exact same k least significant bits as those transmitted.

The interpretation interval can be described as a function:

f(v_ref, k). Let f(v_ref, k) = [v_ref - p, v_ref + (2^k - 1) - p]

Where p is an integer.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    rtp-sn-p valuedefault rtp-sn-p

default

Returns the command to its default value.
value

Specifies the number the value of p in the RTP SN calculation as an integer from 0 through 999.
Usage:

Use this command to set the value to use for p when performing the RTP SN calculation.
Example:
The following command sets the RTP Sequence Number integer “p” value to 100:

    rtp-sn-p 100

rtp-sn-p-override

Allows an override of p in RTP SN calculation. This is disabled by default.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] rtp-sn-p-override

default

Returns the command to its default value of disabled.
no

Disables overriding p in RTP SN calculation.
Usage:

Use this command to allow an override of p in RTP SN calculations.
Example:
The following command enables the override of p in the RTP SN calculation:

    rtp-sn-p-override

sliding-window-ts

Computes jitter as described in RFC 3095,[4.5.4]
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    sliding-window-ts sizedefault sliding-window-ts

default

Returns the command to its default value of 4.
size

Sets the size of the sliding window. size must be an integer from 1 through 1000.

Default: 4
Usage:

Use this command to set the size of the sliding window used to compute jitter for the current RoHC profile.
Example:
The following command sets the sliding window size to 500:

    sliding-window-ts 500

use-clock-option

Controls usage of the RoHC clock option. The clock option informs the compressor of the clock resolution of the decompressor. This allows the compressor to estimate the jitter introduced by the clock of the decompressor when doing timer-based compression of the RTP timestamp.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] use-clock-option

default

Returns the command to its default value of enabled.
no

Disables use of the RoHC clock option.
Usage:

Use this command to enable and disable the use of the RoHC clock option.
Example:
The following command enables RoHC clock option usage:

    use-clock-option

The following command disables RoHC clock option usage:

    no use-clock-option

use-crc-option

Controls usage of the RoHC cyclic redundancy check (CRC) option. The CRC option contains an 8-bit CRC computed over the entire feedback payload, without the packet type and code octet, but including any CID fields,
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] use-crc-option

default

Returns the command to its default value of enabled.
no

Disables use of the CRC option.
Usage:

Use this command to enable and disable the use of the RoHC CRC option.
Example:
The following command enables RoHC CRC option usage:

    use-crc-option

The following command disables RoHC CRC option usage:

    no use-crc-option

use-feedback

Controls use of the feedback channel. A feedback channel sends error recovery requests and (optionally) acknowledgments of significant context updates from the decompressor to the compressor.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Security Administrator, Administrator
Syntax

    [ default | no ] use-feedback

default

Returns the command to its default value of disabled.
no

Disables use of the feedback channel.
Usage:

Use this command to enable and disable the use of the RoHC feedback channel.
Example:
The following command enables RoHC feedback channel usage:

    use-feedback

The following command disables RoHC feedback channel usage:

    no use-feedback

use-jitter-option

Controls usage of RoHC jitter option. The jitter option allows the decompressor to report the maximum jitter it has observed
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] use-jitter-option

default

Returns the command to its default value of enabled.
no

Disables use of the jitter option.
Usage:

Use this command to enable and disable the use of the RoHC jitter option.
Example:
The following command enables RoHC jitter option usage:

    use-jitter-option

The following command disables RoHC jitter option usage:

    no use-jitter-option

use-reject-option

Controls usage of RoHC reject option. The reject option informs the compressor that the decompressor does not have sufficient resources to handle the flow.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] use-reject-option

default

Returns the command to its default value of disabled.
no

Disables use of the reject option.
Usage:

Use this command to enable and disable the use of the RoHC reject option.
Example:
The following command enables RoHC reject option usage:

    use-reject-option

The following command disables RoHC reject option usage:

    no use-reject-option

use-sn-not-valid-option

Controls usage of the RoHC SN not valid option. The sn-not-valid option indicates that the SN of the feedback is not valid. A compressor must not use the SN of the feedback to find the corresponding sent header when this option is present.
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] use-sn-not-valid-option

default

Returns the command to its default value of enabled.
no

Disables use of the sn-not-valid option.
Usage:

Use this command to enable and disable the use of the RoHC sn not valid option.
Example:
The following command enables RoHC sn not valid option usage:

    use-sn-not-valid-option

The following command disables RoHC sn not valid option usage:

    no use-sn-not-valid-option

use-sn-option

Controls usage of RoHC sn option. The sn option provides eight additional bits of SN (Sequence Number, usually the RTP Sequence Number.)
Platform:

ASR 5000

ASR 5500
Product:

HSGW, PDSN
Privilege:

Administrator
Syntax

    [ default | no ] use-sn-option

default

Returns the command to its default value of enabled.
no

Disables use of the SN option.
Usage:

Use this command to enable and disable the use of the RoHC SN option.
Example:
The following command enables RoHC SN option usage:

    use-sn-option

The following command disables RoHC SN option usage:

    no use-sn-option