Re: [6lowpan] How to find the mailbox? (related to "Advertize on Behalf")

[Jonathan Hui <[e-mail]>]

On Mar 30, 2011, at 2:53 PM, Richard Kelsey wrote:

>> Date: Wed, 30 Mar 2011 08:08:19 +0200
>> From: "Anders Brandt" <[e-mail]>
>> 
>> As mentioned yesterday, there is a distinction between Frequently
>> Listening (a.k.a duty cycled nodes) and what I call call-back nodes,
>> i.e. nodes that depend on a router holding a mailbox for that node.
>> Whether that mailbox feature is provided by any router, a few
>> specialiezed routers or the border router is a network implementation
>> decision.
> 
> As you point out, there are lots of ways to do this.  No one
> solution is going to work for everyone.  At one extreme this
> can all be handled by the link layer.  It shouldn't matter
> to the higher layers if a message is polled for, transmitted
> according to some known schedule, or unicast immediately.
> 
> At the other end of the spectrum, it can all be handled at
> the application layer, with the application polling to some
> centralized mailbox which may be anywhere.
> 
> The middle ground, where ND and/or routing get involved,
> seems dangerous to me, exactly because so many different
> approaches are possible.

+1

Both extremes were represented at the mic yesterday and there were certainly concerns with the middle ground approach.  In some cases, I think it will be a combination of both extremes.  The link layer knows best how to contact a duty-cycled node, while the application layer specifies the policy of what to do with packets that experience long communication latencies.  Having another mechanism in the middle would only add complexity in having to combine the particular link layer properties and application layer policies.

--
Jonathan Hui