Re: [Roll] I-D Action: draft-ietf-roll-trickle-mcast-02.txt

"Jonathan Hui (johui)" <> Fri, 19 October 2012 17:31 UTC

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From: "Jonathan Hui (johui)" <>
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Thread-Topic: [Roll] I-D Action: draft-ietf-roll-trickle-mcast-02.txt
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Subject: Re: [Roll] I-D Action: draft-ietf-roll-trickle-mcast-02.txt
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This update includes the new text that was sent out during the last IETF meeting and incorporates comments received since then (special thanks to Robert Cragie, Esko Dijk, Owen Kirby, Joseph Reddy, Dario Tedeschi, and Peter van der Stok).

The following are some open discussion items that were raised in the comments.  Would be great to hear your thoughts.

1) MPL multicast scope.  The current draft allows the MPL multicast scope to be link-local scope or something larger.  On one hand, fixing the MPL multicast scope to be link-local reduces the number of options, makes things simpler, and improves interoperability. On the other hand, doing so will make IPv6-in-IPv6 encapsulation a MUST even when the source and destinations are all in the MPL domain.

2) The S field.  The current draft includes an S field in the MPL Hop-by-Hop Option to indicate the length of the seed identifier.  On one hand, the length of the seed identifier may be inferred by the Opt Data Len field.  On the other hand, if any future specification wants to define additional fields following the seed identifier field, that specification would need some way to indicate the length of the seed identifier.  The S field was originally included to allow the possibility of something like sub-TLVs, that are extensively used throughout RPL.

3) Supporting different Trickle parameter sets.  The latest draft removes a flag that indicates which of two parameter sets to use when disseminating MPL multicast packets.  We removed the flag in attempt to simplify the draft.  Furthermore, it wasn't clear that a single flag (2 parameter sets) was sufficient.

4) Version number field.  The current draft does not include a version field in the MPL Hop-by-Hop Option.  Instead, it sets all reserved bits to zero and requires all devices that implement this draft to drop the message if any of those bits are non-zero.

Jonathan Hui

On Oct 19, 2012, at 10:19 AM, wrote:

> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Routing Over Low power and Lossy networks Working Group of the IETF.
> 	Title           : Multicast Protocol for Low power and Lossy Networks (MPL)
> 	Author(s)       : Jonathan W. Hui
>                          Richard Kelsey
> 	Filename        : draft-ietf-roll-trickle-mcast-02.txt
> 	Pages           : 24
> 	Date            : 2012-10-19
> Abstract:
>   This document specifies the Multicast Protocol for Low power and
>   Lossy Networks (MPL) that provides IPv6 multicast forwarding in
>   constrained networks.  MPL avoids the need to construct or maintain
>   any multicast forwarding topology, disseminating messages to all MPL
>   forwarders in an MPL domain.  MPL uses the Trickle algorithm to drive
>   packet transmissions for both control and data-plane packets.
>   Specific Trickle parameter configurations allow MPL to trade between
>   dissemination latency and transmission efficiency.
> The IETF datatracker status page for this draft is:
> There's also a htmlized version available at:
> A diff from the previous version is available at:
> Internet-Drafts are also available by anonymous FTP at:
> _______________________________________________
> Roll mailing list