Between fading memories and NDA's, it can be hard to track how things happened...but I'm trying to put together some timelines about interprovider peering both through private peering (i.e., at what point it became economic to meet other than through ARPANET/NSFNET) and at exchanges. In the beginning, of course, there was the ARPANET. Then there was the NSFNET. The NAPs were the first recognizable exchange points, with AUPs. NAPs were linked by VBNS. CIX came later, without the AUP restrictions of NSFNET. My impression is that bandwidth into it, at first, was quite limited. At some point, there started to be a business case for large providers to interconnect with bilateral private links as well as at exchanges. When did such links first get used for commercial traffic? In the beginning, were they short-haul connections between cages in exchanges, or WAN links between major provider hubs? I'm referring here only to interprovider links, not to transit customers. Also in the timeline was the advent of true "local" or "metro" exchanges. Going through the archives, the first I see was Tucson. Was that indeed the first cooperative exchange intended to reduce backhaul?