Re: Ted's stub network document: draft-lemon-stub-networks{,-ps}

[Ted Lemon <[e-mail]>]

Since I’m updating the document...

> On Feb 26, 2021, at 12:01 PM, Ted Lemon <[e-mail]> wrote:
>> On Feb 26, 2021, at 11:24 AM, Michael Richardson <[e-mail]> wrote:
> 
>> 2) There is advice about monitoring the RAs from the infrastructure router
>>  (which is probably the home CPE router), and soliciting them regularly.
>>  In effect, the Stub Router can't depend that the CPE router will remain
>>  alive for it's lifetime.
>>  That is, the RA lifetimes tell the client how long it may use the
>>  resource, but not how to determine if the router is alive.  Of course,
>>  power can disappear at any time.
>>  Ted: it seems that maybe neigh-cache entries already have all the timers
>>  and rechecks needed, and maybe the Stub Router can just watch for
>>  the NCE going Stale?
> 
> That would work, but depends on the stub router implementation being able to get a notification that this has happened, which means it’s running in the kernel. I don’t think that’s a likely scenario. Also, NCEs have lifetimes, so they will also outlive on-link routers.

I’ve added this, but please suggest better wording:

	    As an alternative to the vicarious router discovery process described here, the stub router could monitor the presence
	    of the router advertising the on-link prefix in the neighbor cache. If the neighbor cache entry becomes stale, this
	    could be an indication that the prefix is also stale. If the neighbor cache entry goes stale, the router would need to
	    try to refresh it, and if that fails, then the stub router must begin advertising its own on-link prefix on the stub
	    network.


>> 4) I'd like to add a state machine diagram to 3.1.1/3.1.2.
> 
> I think that’s a good idea, although I am not really a fan of state machine *diagrams* — I’d maybe rather just describe the state machine. Diagrams are easy to misread. There are actually several state machines, and each I think is fairly simple, so writing out a list of states, events and state transitions may be practicable.

This is noted, and on the to-do list, but not today. :)