[ppml] [address-policy-wg] Those pesky ULAs again

On 29-mei-2007, at 19:09, Scott Nelson wrote:

>>> Advantages of ULA-C (even to those who claim there are some):
>>> 	Virtually none.

>> I'm sure you don't mind the plane renumbering in flight when it
>> switches from one satellite connection to the next. Myself, I'd like
>> to see the flight systems to have stable addressing regardless of the
>> orientation of the satellite antennas.

> I'm not seeing something here.  Wouldn't the plane have an IP  
> address given to it from the airline?  If the airline needs to  
> renumber, wouldn't they would do it in stages -- as planes land?

If you number the planes from the airline's address space, you need  
to keep rerouting those address blocks for the planes continuously as  
the plane flies around. It's really hard to make that work well, and  
the airline probably needs some kind of world-wide private network to  
do it.

It makes much more sense to give the parts of the plane that need  
connectivity addresses that are tied to the connection they happen to  
have at any point in time. I.e., when it's in the air the passengers  
can email through a satellite link, when it's on the ground the  
service people can access the plane's systems for maintenance. But  
you really want the different systems in the plane to be able to talk  
to each other regardless of what external connectivity there is and  
regardless of any addressing such connectivity brings with it.