Hi Tom,

There's a couple of different ways of interpreting your question, which will impact the answers you get.

You might mean "exchange inter-connections" as "how are the different internet exchanges connected to each other?"

in which case the answer is generally "through the Internet".  ^_^;

You might instead be thinking of "how are different participants in a single internet exchange cross-connected to 

each other?"  -- in which case the answer is "through in-building wiring that often even the building owner isn't 

entirely aware of what path the connections are taking."   ^_^;

You might also be asking about BGP relationships, not physical connections, in which case mining route-views, 

RIPE, and other BGP data sources, along with PeeringDB will allow you to see a percentage of the picture, though

not the entire model.

You might also be asking about "visualization" in the sense of "looking at traffic volumes across interconnections", 

at which point you're whistling in the dark; other than the aggregate traffic volume visualization that some exchanges 

provide, nobody is sharing their traffic graphs externally, sorry.  

So, the first step to getting a meaningful answer is to clarify your question a bit more.

Are you asking about interconnections *between* internet exchanges, or interconnections *within* a single exchange?

Are you looking for physical layer interconnection information, or logical (BGP neighbor) interconnection information?

Are you just looking for a binary "does an interconnection relationship exist", or are you looking to visualize traffic volumes across that relationship?

If you can provide a bit more clarity in what you're looking for, we'll have a better idea of how exactly to tell you you're out of luck.   ^_^;

Thanks!

Matt