I find it interesting that so much of the discussion surrounding net neutrality centers around analogies to other aspects of the modern world. A lot of these analogies are related to the transportation of goods. Courier companies such as UPS and Fedex as well as the highway network in general are the most common examples. In one of the first articles on net neutrality, Saving the Net, Doc Searls argues that the transport analogy is a major impediment to the pro-neutrality side and offers a competing analogy. This post is not about which analogy is better, it is about the problems which occur when using any analogy to discuss a complex topic.
It is easy to understand why people use analogies to discuss complex topics like net neutrality. By allowing knowledge and understanding from one area to be applied to something new, analogies are essentially a way of simplifying the world. Like any simplification, there is always some detail lost.
Analogy is a poor tool for reasoning, but a good analogy can be very effective in developing intuition.
— Barbara Simons and Jim Horning
(Communications of the ACM, Sept 2005, Inside Risks)
The very fact that analogies apply old information to new situations should give us pause in using analogy as a reasoning tool.
To see an example of this problem one only needs to examine what is perhaps the most common analogy used by the anti-neutrality folks. The analogy in question relates to the fact that UPS and other courier companies offer high priority service (overnight) as well as normal service without the negative consequences the pro-neutrality crowd fears.
In order for a courier company to begin to offer overnight package delivery, the company must add new capacity to its delivery operations. For example, a company that ships packages by truck will need to add aircraft to its operations to support cross-continent overnight delivery. Once these aircraft are in place it does not make economic sense to fly them lightly loaded. Instead, the courier company will begin to fill the remainder of the space in the planes with lower priority packages. This has the benefit of reducing the courier’s costs by reducing the number of trucks that are necessary. There is also another unintentional benefit. Although some customers have not paid for overnight delivery, the additional high speed capacity greatly increases the chance they will get that level of service anyway. As the volume of high priority packages grows, the courier’s overall operations must also grow in high priority capacity.
Compare the above situation to packet prioritization on the Internet. Unlike the courier company example, adding a high priority service does not require that the bandwidth provider add new capacity to its operations. There is no way to make light go faster. Packet prioritization simply gives the marked packets first crack at the existing capacity. Assuming the network is properly provisioned (not heavily loaded) the difference in service quality between high and low priority packets is very low, probably unnoticeable.
There is also the issue of reverse economic incentives. In order for customers who are paying for high priority service to notice an improvement the network must be congested. This creates the strange situation where allowing the network to become congested (not upgrading) could result in more customers paying for high priority service and thus increasing the bandwidth provider’s profits.
[Before anyone complains, I realize there are other aspects to network QoS such as number of hops in a path etc. I am not attempting to explain all aspects of network operations.]
On the surface, the analogy between high priority package shipment and high priority packet delivery seems like a good one. Upon closer examination, simple physical limitations show these two worlds to have very different operational characteristics and completely opposite unintentional side effects.
The point of this post is not to argue about the exact details of packet forwarding or courier company operations. The point is that centering the discussion about complex topics like network neutrality around analogies to other systems is foolish. The lost detail results in uninformed decisions.