Re: About draft-arifumi-lin6-multihome-api-00.txt (was Re: Call forpresentations)

[marcelo bagnulo <marcelo@it.uc3m.es>]

On Tue, 2003-06-24 at 09:47, Arifumi Matsumoto wrote:
[...]

> 
> Your understanding about LIN6 is absolutely correct.
> In LIN6, the locator part of an IPv6 address isn't visible
> to upper layers. This makes it possible to continue
> existing sessions even when an LIN6 node moves and
> its address is changed.
> In this model, however, upper layers cannot make any
> controls on outgoing packets' address and route.

Ok. i think we a different idea about this. IMHO, addresses and routes
are IP layer issues, above layers should not be aware of the route used
and they should not select it. For above layers, IP addresses are plain
identifiers of nodes.


 This
> model, we think, doesn't benefit from multihoming.
> 
I do not see what you mean. If the ip layer preserves the established
sessions using a mechanism such as LIN6 or whatever, i would say that
the host is benefiting from multi-homing.

So we make it possible to make an special socket through
> which multiple locators are visible to upper layers
> (application layer). This special socket are implemented
> so that it can co-exist with normal sockets.
> For such a socket, LIN6 is used for address resolution,
> notification and registration. LIN6 layer acquires
> target node's addresses, registers locators to its
> Mapping Agents and notifies address change to the
> corresponding nodes and also to upper layers.
> 
> > An additional question is about address discovery. I mean how do the end
> > nodes find out what addresses are available at the other end? There is a
> > mapping agent mentioned, but where is this mapping agent located? which
> > addresses does it announce? all the available addresses or just the ones
> > that are reachable at the moment? if the latter, how does it find out
> > whether an address is reachable or not?
> 
> These issues are mentioned in LIN6's draft below.
> http://www.lin6.net/draft/draft-teraoka-ipng-lin6-01.txt 
> Briefly speaking, you can get the MA's address by a kind
> of DNS address-to-name translations. By making a query
> ,where an mobile node is, to the MA, a corresponding node
> can get all the addresses the mobile node has even if some
> of the addresses aren't reachable from the corresponding
> node.
> 
So in the multi-homing scenario, where would those MAs should be?

Thanks, marcelo

> > Another question is related to security, i.e. how do you authenticate
> > the addresses actually belong to the node that is claiming its
> > ownership? This is a very important and difficult issue as far i can
> > tell, and it should be addressed.
> 
> This is also mentioned in the LIN6's draft above. In LIN6
> layer, address information are exchanged and updated in
> a secure manner using cookies exchanged through a location
> query to the MA.
> 

> > Finally, how the multi-homed node communicates the alternative address
> > to be used when the address that is being used fails? 
> 
> Our APIs, mentioned in my draft, are used for this porpose.
> By getaddrinfo2(), an application can acquire all the
> addresses of the other end node and by setsockopt()
> an application specify the kernel which address should
> used for destination/source address of outgoing packets.
> 
> 
> I hope you understand what our APIs are for and why these
> are based on the LIN6.
> Any comments are welcome.
> 
> -- 
> Arifumi Matsumoto (arifumi@kuis.kyoto-u.ac.jp)
> Kyoto University
>