Re: [Idr] draft-dickson-idr-second-best-backup-02

Brian Dickson <> Tue, 18 March 2008 16:38 UTC

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Date: Tue, 18 Mar 2008 12:35:40 -0400
From: Brian Dickson <>
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To: Enke Chen <>
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Subject: Re: [Idr] draft-dickson-idr-second-best-backup-02
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Enke Chen wrote:
> Hi, Brian:
> I have several questions below.
> Brian Dickson wrote:
> [snip]
>> I will definitely be modifying the draft, to incorporate N rather 
>> than just 2 for the additional paths.
>> I'll be using most of the walton-draft, as it covers the N-path 
>> codification quite well.
> Have you asked for permission from the walton-draft authors to "use 
> most of the walton-draft", and have you been granted such a permission?

As I haven't made the changes yet, I haven't asked yet.

I will be asking permissions from all of the authors, including the 
authors of the referenced incorporated work.

However, technically, I would note that such permission is not required. 
See section 7.3 of BCP78.

Please don't jump to any conclusions about my intentions, simply because 
I haven't yet asked. I only just got back from the IETF on the weekend! :-)

I plan on using language very similar to that found in the walton-draft, 
where it acknowledges that it itself was making use of earlier work by 
Chen et al.

This is consistent with IETF WG documents and procedures.

> I must be missing something here.  You will be "using most of the 
> walton-draft" in your draft to solve a subset of the problem that the 
> walton-draft has already covered?
No, I am adding in only the elements of the walton-draft to encode N-way 
rather than 2-way additional paths.
And, I will be modifying those substantively, since they do not encode 
order on the multiple paths.

What my draft covers, is strictly a superset, not a subset, of what 
walton-draft covered.

And notably, there are corner cases that walton-draft does not handle, 
that my draft does.
Specifically, the modified step (c) handles cases which the walton-draft 
would not handle, or where it would select infeasible paths.
(This happens to be a critical part of ensuring that the propagation on 
inter-as additional paths is valid and correct. The walton-draft didn't 
explicitly cover inter-as at all.)

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