Re: [homenet] New Version Notification for draft-barth-homenet-wifi-roaming-00.txt

["Ray Hunter (v6ops)" <[e-mail]>]

> Mikael Abrahamsson <mailto:[e-mail]>
> 26 Nov 2015 16:15
> On Thu, 26 Nov 2015, Ray Hunter (v6ops) wrote:
>
>> I have read this draft and find it interesting.
>>
>> The use of host routes would seem appealing to avoid
>> 1) any need for stateful "home agent" and multiple forwarding
>> 2) renumbering of the end nodes when roaming
>> 3) relatively small number of hosts compared to the complexity of the 
>> topology
>>
>> Use of RFC7217 addresses would seem appropriate, but that assumes 
>> that DAD really is reliable at the time a node attaches to the 
>> homenet for the first time.
>
> Wouldn't it be better to adopt 
> https://tools.ietf.org/html/draft-ietf-v6ops-host-addr-availability-02 
> and just give every device its own /64 and move that around?
>
Having a full /64 would seem attractive (for maintaining outbound 
sessions on temporary addresses etc.)

How would you "move a /64 around"?

I'm presume cooperating routers would have to maintain a translation 
table of MAC address to /64 prefix per host wireless interface.

What's the practical difference with moving a /64 (which still requires 
routing changes AFAICS) compared to moving a /128 host route?

What's the practical difference in the trigger for executing the move 
(ND neighbor table update, as opposed to a MAC being detected as having 
changed attachment point)?
> My worry about the whole L3 approach is how long does it take to 
> re-establish packet flows after the L2 wifi handover between APs 
> compared to an L2 only solution?
>
>> What's the benefit/downside of this approach compared to having 
>> roaming nodes actively take part in the HNCP acting as "multi-homed 
>> routers" with an internal (invariant) /64 VLAN used to bind to 
>> applications?
>
> I'd say this approach adds one more layer that needs to come up before 
> packets can start flowing again, especially since it would require 
> routing protocol participation as well, I'd imagine.
>
> If 802.11 can assure L2 handover in 1 second (I don't know how long 
> the handover time is, just guessing), how much are we willing to add 
> in time because of L3 mechanisms added on top of this, before packet 
> flows are up and running again?

-- 
regards,
RayH
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