Shortest path to the world

Sean Donelan sean at donelan.com
Wed Jul 15 21:39:05 CDT 2009


On Wed, 15 Jul 2009, Randy Bush wrote:
>> The typical network architecture problem, what are the best (shortest
>> latency, greatest bandwidth, etc) locations to connect to the every
>> nation in the world?  As you increase the number of locations, how do the
>> choices change?
>>
>> If you only had small (2 3 5 7 11) number of locations, where would they
>> be?
>>
>> And what data do you have to prove the choices are best?
>
> it would help if you said how you measure 'best' or 'better'.

As I said in the original message, combination of minimizing latency 
(smallest RTT to the most IP endpoints) and maximizing bandwidth (largest 
number of bits per second successfully received at the most IP endpoints 
in the smallest amount of time) from the locations identified as best.

On Wed, 15 Jul 2009, Jareon Masser wrote:
>Depends completely on what the data is and why you want to send them
>from A to B and if A and B are inside your network or not etc etc etc 
>etc.

As I said in the original message, every nation in the world.  Or more 
specifically the largest number of IP endpoints reachable in the most
nations from the locations chosen.

A = the few locations you pick
B = every other IP endpoint reachable from those locations

If every point B in the world is inside your network, awesome.  But 
highly unlikely.

More than likely to maximize reachability, minimize latency, the 
highest goodput, and most availability will require some combination 
starting locations and ISPs.

The data is IP applications in use now and in the future.  Why do you want 
to send them from A to B, because you never know what is going to happen
in the world and you want to be prepared for any point B to have the best 
chance of being able to effectively communicate with the chosen points A.

On Wed, 15 Jul 2009, Bill Woodcock wrote:
>However, if one wanted the beginnings of an answer, without nailing
>down any of the specifics, merely looking at the quantity of routes
>available at each IXP would let you know, on average, how many paths
>there were on offer to each destination.

The starting locations aren't necessarily IXPs.  They could be ISPs
with full transit connections at the chosen locations.  But the goal
includes maximizing reachability to the world, which probably means a
full transit connection near many other ISPs would do better than a full 
transit connection far away from many other ISPs.

>As others have noted, this is a many-variables sort of problem, and to
>answer it well requires nailing down a few of those variables

True, optimization and constraints solving is easier with fewer variables.
There are also researchers that seem to spend lots of time measuring
the Internet and collecting data for all sorts of reasons.  When creating
graphs of the Internet, one of the basic problems every mapper has to
solve is deciding where are the "centers" of the map.





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