Re: [rohc] checksum in R-1

["Lars-Erik Jonsson" <lars-erik.jonsson@ericsson.com>]

>Folks,
>
>I've been going over the packet header formats and the
>extension formats.
>
>The R-1 format does not have a checksum.
>Still, it can have an extension (and there
>is no extension which carries a checksum). So,
>am I to conclude that
>
>A) the only way to update the context in R-mode
>   is to use R-0-CRC or UOR-2, or
>
>B) there is a bug in the extension formats in that
>   there should be a way to add a CRC to an extension?
>
>I suspect that A is the correct alternative, but I recall
>earlier discussions where people have talked about CRCs in
>extensions, so I would like to have this confirmed.


Yes, A should be the right answer. In R-mode, all packet with CRC will update
the context and an ack will be sent. Further, only packets with CRC can update
the context. If context updates are not required, R-1 is used instead of R-2 and
R-0 is used without CRC.

/L-E