In the past we have considered the initiator of IP transactions to be irrelevant and had no-charge peering for networks that basically send a similar number of bytes to what they receive.
So what do we do when that is no longer the case?
Pray someone doesn't write a call-back protocol, so traffic flows in the opposite direction from the original initiator of the IP 'transaction'. That becomes popular in a webbrowser. Or a popular game. Then you'd have to monitor more information than just total traffic flow in and out of an interface. For video and voice over IP type services, the traffic flow should (largely) be symetrical. But what else would be that makes this issue complicated? Right now the name of the game is content. Email, web, news, realaudio, realvideo. Later on when interactive (ie symetric traffic) applications like voice/video over IP come into play, wouldn't it make more sense to handle 'interconnecting' between two different voice/video services by some other way? (Please, if I've missed something here, I'd be glad to know...) Puzzled, Adrian