Re: [DNA] DNA BCP Submission

[Sathya Narayanan <sathya@research.panasonic.com>]

Dear JinHyeock -

>I agree that 'RA with current active prefix' can be used for link 
>identity detection but kindly take notice an adverb 'PROPERLY'. 
>That's why I wrote that it can't be a link identifier, NOT it can't 
>do link identity detection. 
>  
>
ok. And, my point is that as long as you can do link identity detection 
even though you don't define a link
identifier it is still a good way to go.

>If a host receives an RA with its current active prefix, it means it still 
>remains at the same link. However, if a host receives 'an RA with 
>a different prefix', it can't check for link change with it. 
>  
>
A timeout without receiving a 'RA with current active prefix' can be 
used to indicate link change. Right?

>In this framework, because current active prefix doesn't satisfy
>2), it can't be a link identifier, though I agree that it can be used 
>to check for link change. 
>
>In CPL or LinkID (by Brett), a link change can be detected instantly, 
>when a host get a different link identifier, such as the complete 
>prefix list in CPL or LinkID option in LinkID.
>  
>
ok.

>We expect 'link identifier' to EXPLICITLY represent a link identity
>and have the following two properties. 
>1) When the same link identifer arrives, it means the same link.
>2) When a different link identifer arrives, it means a different link.
>  
>
I agree with these two properties with one 'little' caveat - these two 
properties need to hold only for a
particular node in question. i.e. two nodes in the same link could be 
using different 'identifiers' to represent
the link as long as within each of them the above two properties hold. 
You seem to be making
his point below, but ...

>To have the above properties, all the nodes adopting the same 
>link identifier method, whether it be CPL or LinkID, should agree 
>on the same, hence unique, link identifier. For example, if in a 
>link, a node use CPL and the other use LinkID, then they may 
>have different link identifers. However, among the nodes using CPL,
>or any other link identifier, there can be only one link identifier
>for a link. Otherwise 2) can't be satisfied.
>  
>
even within a same scheme , two nodes using the scheme could use 
different 'identifier', as long as the
above two properties hold within the node (neither CPL nor LinkID is an 
example for this). I guess,
you know where I am going with this. In my proposed solution draft, RRD: 
I am trying to use the current
prefix and force the timeout within a short duration by defining new 
timer for the current router. Even though
it doesn't define a 'unique' identifier for every node in the link, I 
think it is reasonable approach to achieve
link identity detection, with its own advantages (and ofcourse, 
dis-advantages).

best regards,
Sathya