Re: [DNA] [Issue X] LinkID v.s. Landmark Prefix

[Brett Pentland <brett.pentland@eng.monash.edu.au>]

JinHyeock Choi wrote:
> Dear Brett
> 
> Thanks for your summary. I assume Landmark/ CompleteRA will follow
> the memo.  
> 
> 
>>For Landmarks:
>>
>>   If a prefix is removed, the host will receive a "NO" answer, which
>>   also include prefixes that are on the link and have been seen by the
>>   host before so it can see there is no link change and yet will also
>>   know that the prefix it was using as a landmark is no longer valid.
>>   (I think we need text to clear that up)
> 
> 
> So in this case, the known prefix in the RA overrules "NO" answer. 
> Right? 

See my answer to Syam.

>>For CompleteRA (which is proposed as a fallback for when it is not
>>possible to use landmarks):
>>
>>   By its nature it creates overlap between the sets of RAs advertised
>>   by the routers on a link.  It doesn't matter whether the sets
>>   agree completely or not, as long as there's overlap (because link-
>>   change is detected by receiving a RA with a set disjoint from the
>>   set of prefixes the host has seen on the link).  The pathological
>>   case that we may need to take action to avoid is where a router
>>   that is currently configured with all of the prefixes in use on a
>>   link, suddenly has all of them removed and replaced with a new
>>   disjoint set.  We need to add some text to say not to do that.
> 
> 
> So I understand you try to assure that there always a overlapping 
> prefix among CompleteRAs even under prefix change. Right?  

Yes.

> I admit that I don't look over Landmark/CompleteRA 01-draft but the 
> above seems a little different from what I remember. I think it would
> help to write those down lest there should be unnecessary confusion. 

OK.

Brett.