Re: [DNA] Feedback on draft-ietf-dna-cpl-00.txt

[JinHyeock Choi <jinchoe@samsung.com>]

Dear Christian

> Besides, has there been a discussion in DNA or elsewhere as to what a
> reasonable upper bound on the handover frequency could be?  If there
> was, it might be good to put a link into your document.

No, AFAIK. 

> >> I do understand that CPL is 100% reliable, even in high-speed
> >> scenarios, when the prefix sets in RAs from the same link are
> >> guaranteed to overlap.
> > 
> > This is a very good point, really an acute observation. Thanks. Yes,
> > there will no mistakenly assuming a link change because of common
> > element (prefix) in (any two) RAs.
> 
> Right, and it would be easy for network administrators to set IP links
> up this way.

I guess, yes, in the most cases. 
 
> The only issue I see at this moment is IP links which have so many
> prefixes that all of them do not fit within a single RA.  In this
> situation, the prefix sub-set advertised in one RA might not overlap
> with the prefix sub-set advertised in another RA, even though the
> complete prefix lists of any two routers on the same IP link do overlap.

I see.  
 
> Of course, a RA daemon can be configured (or patched) such that any two
> successive RAs have overlapping prefix sub-sets.  A RA damon can also be
> configured/patched such that the prefix sub-sets of all of its RAs
> overlap (for instance, by choosing one common prefix).

ok. 
 
> However, while this approach helps, it still cannot prevent the MN from
> seeing two successive RAs (from the same IP link) with disjunct prefix
> sub-sets:  One reason is RA loss, another is multiple routers on the
> same IP link.

ok. 
 
> To coordinate multiple routers on the same IP link, one would end up
> having to choose one common prefix which all of the routers put in all
> of their RAs.  
 
I agree. For 100% certain CPL, 

in theory, it is enough that 
 
"Any two RAs in a link have A common prefix." 

But in practice, it would be better that

"All RAs in a link have THE common prefix." 

Let me underline the above with an example. 

Assume three RAs, RA[1], RA[2] and RA[3]. 

The first one means that any two RA[i] and RA[j] have a common prefix. 
But there may not be  a common prefix among all threee RAs.  

The second one even implies that. 

> And that would effectively be the Link ID proposal. ;)

Now I see much similarity between the above and LinkID draft. 
Thanks for a new insight. 

I'll think over their relationship. Also your feedback on LinkID 
draft will be of much help. 

Thanks in advance for your kind consideration. 

Best Regards

JinHyeock