Re: [DNA] Confirming today's face-to-face meeting decisions

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

Sathya Narayanan wrote:
>>There may be extra cost in making all the routers on a link agree on
>>a "link scoped identifier", but that is an out of band management 
>>cost.Using "does this landmark still exist" has a cost during 
>>movement in
>>that there is no negative acknowledgement and we have to wait for a
>>timer to expire if the link is new and the landmark does not still
>>exist.
> 
> Yes. I agree.
> 
> Few points:
> 1) For aguments sake, if we find out that the out-band cost is so high it is not going to be deployed in most scenarios, it still a bad idea to work on it. Again, my only request is that we do this cost analysis using some objective way to measure this cost.

Agreed.

> 2) Whether immediate change is detected in link-scoped identifier is actually not clear - this is primarily because of the non-dependency of the method on L2 trigger (and that is arguably a good thing), so the average gain in the detection time for link-scoped identifier approach MAY not be very high. Again, we need some analysis.

I think this is a separate problem.  The point is in being able to make
a correct decision based on the reception of a single RA.  How you get
that RA is a separate problem.

> 3) I am not recommending timeout as the only change detection - if you think about the mechanism proposed in RRD, when the 'landmark still exists?' question is asked, if you receive a 'this NEW landmark exists' answer thats an indication of link change. Ofcourse, you need to authenticate this response - but in most cases the router that responded is likely to be the router you are going to use as default router and you need to authenticate it anyway.

I can't remember the details of RRD - are you saying that there is a way
for an RA with a prefix that you haven't seen before indicates a link
change as oposed to a new router on the same link?

Brett.