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

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

Hi Syam,

>>>>> These are my line of thoughts. We can't avoid a temporary flapping 
>>>>> for the related set, the set of
>>>>> all prefixes
>>>>> on a link. In linkid scheme, one item (linkid prefix) of the set 
>>>>> matters for DNA
>>>>> performance.
>>>>> So we designed a few special schemes for the linkid prefix so that
>>>>> linkid prefix(es)
>>>>> won't give incorrect information about a link change, even under
>>>>> temporary flapping.
>>>>>
>>>>> But for Complete RA or Landmark, IMO, we need to adopt similar 
>>>>> schemes such as "Linkid Prefix List" or "Old linkid advertising 
>>>>> rule" to all
>>>>> prefixes because we
>>>>> don't know which prefix will affect DNA decision.
>>>>
>>>>
>>>>
>>>> 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    know that the prefix it was using as a landmark is no longer valid.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)
>>>
>>>
>>>
>>> A host may get 'YES' answer from a Router (R2) before the 'NO' answer
>>> from Router (R1) because the deletion of the prefix (P1) at R1 might 
>>> not have
>>> propagated to R2 at the time of answering the landmar query for P1.
>>
>>
>> Yes, and as far as DNA goes that is the correct answer in that there is
>> no link change.
> 
> 
> What if you get answer 'NO' first?
> Will you check with the prefixes received in the RA?
> This looks better compared just depending on the
> Landmark answer. Otherwise host makes wrong decision.
> 
> [cut]

This question is one of the open issues (9).  My personal opinion is
that yes, the host should check the prefixes and if it sees overlap with
the prefixes it has already seen on the link, should decide that link
change has not taken place.

Brett.