Subject: [rohc] CRC correction algorithms in ROHCv2

From: Anil Maguluri <[email-masked]>
Date: Mon, 21 Dec 2009 14:54:15 +0530

Hi All,

Please clarify whether my understanding is right or not.
As per my understanding, there is no need of CRC Correction algorithms in ROHCv2
because every packet has CRC in ROHCv2. As you know the CRC Correction algorithms
are clearly mentioned in ROHCv1 (RFC 3095).

But, the RFC 5225 has the below information:
"6.4. Reconstruction and Verification
Validation of the IR header (8-bit CRC)
The decompressor MUST always validate the integrity of the IR
header using the 8-bit CRC carried within the IR header. When the
header is validated, the decompressor updates the context with the
information in the IR header. Otherwise, if the IR cannot be
validated, the context MUST NOT be updated and the IR header MUST
NOT be delivered to upper layers.

Verification of CO headers (3-bit CRC or 7-bit CRC)
The decompressor MUST always verify the decompression of a CO
header using the CRC carried within the compressed header. When
the decompression is verified and successful, the decompressor
updates the context with the information received in the CO
header; otherwise, if the reconstructed header fails the CRC
verification, these updates MUST NOT be performed.

A packet for which the decompression attempt cannot be verified
using the CRC MUST NOT be delivered to upper layers.

Decompressor implementations may attempt corrective or repair
measures on CO headers prior to performing the above actions, and
the result of any decompression attempt MUST be verified using the
CRC."

Please clarify the below queries.
Is CRC Correction algorithms are used in ROHCv2?
If yes, where did they mentioned the procedures?

Thanks for your support.

Regards,
Anil Kumar Maguluri

________________________________
This Email may contain confidential or privileged information for the intended recipient (s) If you are not the intended recipient, please do not use or disseminate the information, notify the sender and delete it from your system.

______________________________________________________________________