In a word, non-discrimination. The trick is in how that duty is made real. That deal, in turn, is to serve as a benchmark for sharing deals with other ISPs. The Earthlink deal is therefore the linchpin of the regulations and without that being available it is next to impossible to evaluate the real consequences of the mandatory access obligation or the benefits likely to result. We can make a number of general points.
Mandatory access can impose substantial costs on the owner of the shared asset.
If the ISP agreements do not force the requesting ISPs to internalise the costs of their requests, we will have too much sharing and wasted resources. These costs could degrade the asset in hand and, maybe more importantly, reduce the incentive to improve the asset over time. In an industry going through rapid changes we should be nervous about a substantial brake on progress. Non-discrimination has proved tricky to implement in other industries and there is every reason to think that that will be the case here. AOL and Time Warner were willing to plunge forward in spite of the obligations imposed by the consent decree.