RE: [rohc] draft-ace-robust-hc-01.txt

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Mon, 13 Mar 2000 zhigang.liu@nokia.com wrote:

> I guess the CRC/Checksum at different layers always trigger
> discussions (as in pilc). From the header compression point
> of view, the design of the error detection at upper layer 
> (UDP, etc) and the link layer should be done together.

layering/IPSec etc. do get in the way here.


> > 4.2 - 'Error detection is beneficial, but optional'; I can see
> >       this becoming a MUST as far as headers are concerned...
> 
> No. It states "Error CORRECTION is beneficial, ...". 
> 
> It is certainly a MUST to have error detection.

mea culpa. It will still be a MUST to correct header errors IMhO.


> > Ordered flow requirement is implicit, rather than explicitly stated.
> 
> What do you mena? Ordered flow before compressor, or between 
> compressor and decompressor? ACE can handle adaptively the 
> misordering before compressor. It can also handle the latter 
> case with the cost of efficiency.

Efficiency cost? I couldn't find that bit. (There's a mention in
2.2.3: affect not effect there) I missed 4.1, which is the explicit
ordering statement I was looking for. ACE is assuming that it's
working across an ordered link, yes?


> > Anyone want to come up with a header compression scheme
> > that works well with IPSec?
> 
> Good, but difficult question. Basically, you can only compress
> a header that is clear (i.e. un-encrypted).

I was wondering about compressing authentication overhead; some people
believe authentication will be used on a hop-by-hop basis to give you
IP header checksum functionality in IPv6...

L.

> 
> Thanks for comments, Lloyd. I feel there are
> some related topics between the work of rohc
> the one of pilc. I hope I have time to follow
> the materials generated at pilc.
> 
> Zhigang

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>