On Wed, 2008-11-19 at 16:46 +0100, Pascal Thubert (pthubert) wrote:
> Also, there are tons of legacy field buses protocols in that space that
> we will be tunneling over UDP/6LoWPAN. In that case also, the checksum
> will be elided.
How can this happen with legacy protocols. They do not know about IP
and IPv6 and the pseudo header so they will not calculate a MIC over
anything but their own data, unless you are saying that the code that
tunnels the protocol calculates yet another mic over the tunneled
protocol and the IP header. Is the udp checksum calculated and covered
by the MIC?
geoff
>
> Pascal
>
> >-----Original Message-----
> >From: Erik Nordmark [mailto:[EMAIL PROTECTED]
> >Sent: mercredi 19 novembre 2008 15:42
> >To: Carsten Bormann
> >Cc: Pascal Thubert (pthubert); Shoichi Sakane; 6lowpan; Geoff Mulligan
> >Subject: Re: [6lowpan] UDP checksum elide
> >
> >Carsten Bormann wrote:
> >
> >> One the way from the correspondent node to the 6lowpan node, an app
> that
> >> implements the ULTP computes the MIC to allow the compressor at the
> >> 6lowpan boundary to check it and, if that *and* the UDP checksum were
> >> correct, to compress away the UDP checksum.
> >
> >What happens if I have an application on a correspondent node which
> >sends a regular UDP packet? (i.e., without the ULTP MIC) How can the
> >compressor tell the difference between such a UDP packet and a UDP
> >packet which includes the ULTP MIC?
> >
> > Erik
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