RE: Identification, layering, transactions and universal connectivity

["Tony Li" <Tony.Li@procket.com>]

|    It's not so much that we must desperately try to find the 
|    best address 
|    pair. BGP doesn't give us that either. But it's essential 
|    that we're 
|    able to weed out the very bad pairs quickly. It would be 
|    very helpful 
|    if we had some hints in the mapping system for this, such 
|    as "this is a 
|    low bandwidth/expensive address, only use as a backup" or 
|    "this is an 
|    address with partial connectivity (ie globally unique not globally 
|    routable) so only use when you know it's reachable".


Well, you're already into developing a global policy language 
for locators.  Seems expensive.


|    80/20 rule?


Exactly.


|    Yes. But the question is: do we want to go evaluate connectivity 
|    properties for half a dozen round trips before we do 
|    anything, do we 
|    choose something and go with it until we notice it doesn't work so 
|    well, or do we combine these by starting the communication 
|    immediately 
|    using one address pair and then evaluate connectivity in 
|    the background?


If we don't proscribe or prescribe, then this is just left as an
implementation detail.


|    How much magic do we need in the application to enable this 
|    differentiation?


Or in the kernel.  It depends on whether or not you're willing to add
to the API.  If you're willing to say, make it a socket option, then
all of it just goes in the kernel once.


|    > The network control plane does not change from the functions
|    > that we have available today.  In other words, the problem
|    > is already solved.
|    
|    ???


Restated: if we don't have to distribute more/new/timely information
to support 'intelligent' locator selection, then we don't have to 
make modifications to the routing subsystem and can defer all of
the 'magic'.  This makes migration easier as even the simplest of
algorithms can be used initially to select locators and can then
become more sophisticated as time progresses.

Put yet another way: let's remove the complexity of locator selection.
If simplistic turns out to be insufficient, then let's at least take
out fancy information distribution and be a bit nearer perfection.

Tony