The Federal Communications Commission has committed to the concept of net neutrality, but the recent spat between Level 3 and Comcast highlights some of the sticky enforcement issues that it brings up.

In a speech given in Washington, FCC Chairman Julius Genachowski said he circulated a set of rules of the road for keeping the Internet an open platform. The full Commission will vote on the proposals at its Dec. 21 meeting.

The speech has already drawn fire, even from within the agency. Republican FCC Commissioner Robert McDowell issued a statement saying that the proposals rules would upend three decades of bipartisan and international consensus that the Internet is best able to thrive in the absence of regulation.

The dispute between Level 3 and Comcast is one over payment for network capacity. But determining motives is not straightforward. Net neutrality is based on the premise that lawful content - whatever it is - should be given equal access to the networks. Neither the FCC, nor proponents of net neutrality, has opposed differential payment for bandwidth.

Comcast says Level 3 was asking for too much bandwidth, because many people - including Comcast's own customers - were streaming Netflix videos to their computers. That drove a disproportionate amount of traffic over Comcast's network. In a letter to the FCC Comcast claims it was twice as much traffic from Level 3 as Comcast was sending back. In such situations, it isn't unusual for network providers to pay extra - so-called peering agreements.

Level 3 says the problem is Comcast wants users of Netflix's video service to pay more because of the content. Comcast recently inked a deal to buy 51 percent of NBC Universal, which in turn owns 30 percent of Hulu, a video delivery service. Comcast itself is in the cable TV business. So there have been accusations that Comcast wants to force Netflix's costs up, at the very least, and stop the service at worst.

Comcast, meanwhile, says Level 3 has become content delivery network rather than a simple backbone - subject to paying rates similar to Akamai, for example.

The question arises whether the issue of payment is a cover for Comcast to stop certain content - which would violate one of the principles of net neutrality - or Level 3 is attempting to get free capacity that violates the peering agreement.

One of the key points is transparency. Genachowski said consumers have the right to know how networks are managed. Sunshine can help solve problems early, reducing the number of issues that come to the FCC, he said. Comcast says it is just managing the network for best performance - something the FCC has said does not violate the principle of net neutrality.

Genachowski's speech explicitly recognized that, saying that broadband providers need the flexibility to manage their networks to address congestion - which is precisely what Comcast says it is doing.

The FCC, meanwhile, has said it will look into the matter, but has given no indication of what it would do.

Then there is the question of what powers the FCC has. The new class of Republican Congressmen may want to curb the agency's powers. And some telecommunications companies, notably Verizon, have asked that the FCC make only temporary rather than permanent rules until Congress addresses the issue of net neutrality via legislation.