Jon, <snip>
Ratios only make sense between peers. When you're buying transit, you don't get to enforce ratios and tell your transit providers you're not going to pay (or they're going to pay you) because they're sending you too much traffic. Back when I ran a dialup network, and our traffic profile was maybe 5:1 input vs output, UUnet would have laughed at me and shut us off if I told them "you're sending us traffic at a 5:1 ratio...because you're sending us so much more traffic than we send you, you're going to have to pay us to deliver that traffic." Comcast can only get away with that because of their monopoly (captive userbase) and size.
I agree with most of your reply. In regards to ratios, I firmly believe they don't make sense between peers as well. When you operate an eyeball network, you need to expect that your users are pulling the data from the content providers. Your ratios will always be unbalanced with most of your peers. If ratios are really a concern and you really need to maximize your port capacity, there are ways to balance this; balance your customer base. Start hosting content. Now, this might not help on private peering interconnects, but if you peer publicly, this will help you balance (and take advantage of) your public peering capacity. Either way, ratios are very 1990s. As has been mentioned before, it was more of an excuse not to peer by the monopolistic entities that made up a big portion of the Internet in the 90s and isn't very relevant today. Randy