Re: [Roll] [6lo] FW: New Version Notification for draft-thubert-6lo-routing-dispatch-00.txt

Robert Cragie <robert.cragie@gridmerge.com> Mon, 01 December 2014 18:17 UTC

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Date: Mon, 01 Dec 2014 18:16:53 +0000
From: Robert Cragie <robert.cragie@gridmerge.com>
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To: "Pascal Thubert (pthubert)" <pthubert@cisco.com>, "6lo@ietf.org" <6lo@ietf.org>
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Cc: Routing Over Low power and Lossy networks <roll@ietf.org>, "6tisch@ietf.org" <6tisch@ietf.org>
Subject: Re: [Roll] [6lo] FW: New Version Notification for draft-thubert-6lo-routing-dispatch-00.txt
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Hi Pascal,

I agree that with hindsight it could be considered a bit greedy of 
RFC4944 to allocate 1/3 of the dispatch code space to the mesh header 
(especially when the definition of it itself is questionable) but what 
you are advocating is a replacement, not a framework extension. RFC6282 
only deprecated an ESC code, i.e. something which had not yet been used, 
which is not quite the same. This effectively makes this at best a new 
version of 6lowpan (which is difficult to distinguish) or at worst 
arguably a whole new protocol.

Whilst hindsight is a wonderful thing, it can lead to the situation 
where a standard never stands still and keeps evolving. This makes it 
very difficult to develop products as there is always the fear that 
something will change the next year. Upgrading products is often quite a 
difficult process, especially in the case where there could quite 
feasibly be thousands of deployed devices which may have limited upgrade 
capability.

I would like to hear what other people think about this.

Also a comment re. section 8, I think the 'I' field needs to be 1, as 
'Size' represents the HopsLft field, not the size of the header. It also 
doesn't seem to cover the Deep Hops Left concept in RFC4944.

Robert

On 27/11/2014 2:03 PM, Pascal Thubert (pthubert) wrote:
> Dear all:
>
> This is a response to the question about the compression of RFC 6553 on top of RFC 6554.
> It seems exaggerated to consume a dispatch type for the RPL option only.
> But here, we introduce a routing header which is the equivalent of the mesh header in RFC 4944; we propose a compressed TLV format that can encode RH3, RPL option, IP-in-IP, and is further extensible, for instance for upcoming  BIER.
> As it goes, the mesh header consumes 1/3 of all the 6LoWPAN addressable space for application only in Mesh-under.
> This draft reuses that space in Route-over with the assumption that Route-over will not co-exist in a sma enetwork with Mesh-under encoded in the RFC 4944 fashion.
> If there is effectively a need for co-existence, devices have to implement the new Mesh-under format that is also proposed in the draft.
>
> Comments welcome,
> Pascal
>
>
> -----Original Message-----
> From: internet-drafts@ietf.org [mailto:internet-drafts@ietf.org]
> Sent: jeudi 27 novembre 2014 14:36
> To: Pascal Thubert (pthubert); Pascal Thubert (pthubert); Laurent Toutain; Carsten Bormann; Laurent Toutain; Dr. Carsten Bormann
> Subject: New Version Notification for draft-thubert-6lo-routing-dispatch-00.txt
>
>
> A new version of I-D, draft-thubert-6lo-routing-dispatch-00.txt
> has been successfully submitted by Pascal Thubert and posted to the IETF repository.
>
> Name:		draft-thubert-6lo-routing-dispatch
> Revision:	00
> Title:		A Routing Header Dispatch for 6LoWPAN
> Document date:	2014-11-25
> Group:		Individual Submission
> Pages:		19
> URL:            http://www.ietf.org/internet-drafts/draft-thubert-6lo-routing-dispatch-00.txt
> Status:         https://datatracker.ietf.org/doc/draft-thubert-6lo-routing-dispatch/
> Htmlized:       http://tools.ietf.org/html/draft-thubert-6lo-routing-dispatch-00
>
>
> Abstract:
>     This specification provides a new 6LoWPAN dispatch type for use in
>     Route-over and mixed Mesh-under and Route-over topologies, that
>     reuses the encoding of the mesh type defined in RFC 4944 for pure
>     Mesh-under topologies.  This specification also defines a method to
>     compress RPL Option (RFC6553) information and Routing Header type 3
>     (RFC6554), an efficient IP-in-IP technique and opens the way for
>     further routing techniques.  This extends 6LoWPAN Transmission of
>     IPv6 Packets (RFC4944), and is applicable to new link-layer types
>     where 6LoWPAN is being defined.
>
>                                                                                    
>
>
> Please note that it may take a couple of minutes from the time of submission until the htmlized version and diff are available at tools.ietf.org.
>
> The IETF Secretariat
>
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