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Re: [Roll] [6lo] RPL artifact compression discussion

Michael Richardson <mcr+ietf@sandelman.ca> Mon, 23 March 2015 22:48 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
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Date: Mon, 23 Mar 2015 18:48:48 -0400
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Subject: Re: [Roll] [6lo] RPL artifact compression discussion
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Robert Cragie <robert.cragie@gridmerge.com> wrote:
    > <RCC>There is - it's IPHC. You can use IPHC twice as we discussed in
    > the recent call.</RCC> 

Thank you for your reply, and reminding me that I didn't followup with you on
this question.   So, I'm not really sure how you signal this.

This is what I see at this time:

15.4 header stuff.
Dispatch    = LOWPAN_IPHC (0b1110 111N).      (rfc6282. section 4/5)
            here we want to put another compress header, so N=1.
            base format, with "NH=1"
                 NHC_1=0b1110 EID NH      EID=5,NH=1
            = here we would have RPI
                 NHC_2=???

Now if NHC_2 = 7, then an IPIP header follows.
If the NHC_1's NH=0, then an entire byte follows for something that
doesn't fit into the EID (e.g. IPsec ESP).

I don't know I signal that what follows the RPI isn't an IPv6 header
(uncompressed), but rather another LOWPAN_IPHC.

Maybe you have a better way of presenting this detail.

-- 
Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-

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