Re: [DNA-BOF] Detecting Network Attachment BoF description (rev 2)

[Alper Yegin <alper@docomolabs-usa.com>]

> How about we call this "Link-layer only" handover?
> Is there a better term?

I cannot think of any...

>> Or, host might change its access point and consequently access
>> router, but
>> the two routers might be advertising the same prefix. In that
>> case, IP
>> address of the host does not change, but default router
>> information must
>> change. So, even if the subnet does not change, host has to react
>> to this.
> 
> I don't think that this happens if there is a common
> wired link between the ARs and APs  (it can only occur
> in a multilink subnet).
> 
> Is this what you meant?
> If so, should we be thinking about multi-link subnets?

Yes, why not? Unless IETF decided to not adopt
draft-ietf-ipv6-multilink-subnets-01.txt... This is an expired draft, that
was once an official IPv6 WG item. Later it was decided to tackle this
elsewhere, and I don't know its latest status...

> 
> I know that there is the issue of router failure.
> Our solutions should definitely tolerate this.
> 
>> Or, the link, default router and prefix change at the same time.
> 
> How about we call this "subnet change" ?

OK.

> 
>> On the other hand, the link might not change (i.e., host is still
>> connectedto the same media), but the configuration parameters
>> change. For example
>> router renumbering. Now host has to react to this too.
> 
> You are definitely right here, although the presence of
> a new prefix will be evident if the node is already (physically)
> attached.

Unless the host is aware of physical connections, it cannot know what is
going on, right? 


> 
> I'm not sure that we need to deal with this though, since
> this is already supposed to be dealt with in ND/RR.

Good point. Agreed.

> 
> 
> I think one of the problematic sentences was:
> 
> "For these nodes, it is also important detect if an acquired
> link is new, or has already been visited"
> 
> I've changed link to subnet.  Does this help?

Not really. Because even if the subnet is the same (if we are defining the
subnet based on the prefixes) there might need to be changes (see earlier
discussion on multi-links).

I also think that talking about re-visiting same links/subnets is about some
(risky/not_so_trivial) optimizations.

    This information may be used to distinguish between
    events where configuration must be initiated, or a
    host already has valid configuration.

Nothing guarantees the validity of the previous configs once the host moves
off-link. There still needs to be some protocol exchange between the host
and the network elements to ensure validity of the parameters.

Alper




> 
> Greg
> 
> 
> 
>