Re: [DNA] Prefix information for link identification in DNA

[Erik Nordmark <erik.nordmark@sun.com>]

Bernard Aboba wrote:

I don't have a problem with the desire to generalize things to not 
assume routers, but the devil is in the proverbial details.

> +For a particular network, the host SHOULD use the addresses of
> +local routers (preferably default gateways) as its test nodes,
> +although any address on the target network will suffice. 

As somebody else pointed out, you can't select any address as a test 
one, since that node might be mobile as well. So having the PDA in my 
left pocket pick the IP+MAC of the PDA in my right pocket would be 
catastrophic, since both of them are likely to move at the same time.
So we should change the above to
 > +For a particular network, the host SHOULD use the addresses of
 > +local routers (preferably default gateways) as its test nodes,
 > +although any address on the target network that is know to not be 
moving around will suffice.

This leads to the question of how can a host determine which test 
address can be safely used short of manual configuration.
If this is the case I think we should make this explicit in the 
document, for instance by saying:
	Unless the the host has been manually configured with a test
	node, or otherwise knows a test node which is it certain is not
	mobile, the host should select the default router(s) as the test
	node(s).

   Erik