Network Neutrality: Classification of Arguments For and Against
This page aims to distinguish different arguments and reasoning in the debate around network neutrality, or control over traffic transmission on digital networks. The creation of this page was prompted by a view that people arguing for and against network neutrality use multiple definitions of the term and mix together many arguments on different levels. The purpose of this page is not to air polemics, but to elucidate the various points made for and against various forms of network neutrality.
The document treats network neutrality is a business practice, and therefore does not cover related topics such as copyright enforcement, censorship, and surveillance in detail. Essentially, the document covers a public issue that started as a set of economic concerns and has been invested by debaters with moral concerns.
Varieties of Intervention in Internet Traffic
Much confusion among the public, and many instances of debaters talking past each other, are caused by the possibility of differentiating among Internet traffic in many different ways.
In all these cases, an Internet service provider monitors traffic at its routers and chooses to drop certain packets entirely or to send them at a slower frequency. When traffic uses TCP, dropping selected packets near the beginning of a session causes the sender to throttle back the speed of transmission, because TCP assumes that the lack of acknowledgment indicates a congested route.
A router is normally expected to check only crude indicators of traffic such as IP address and port (characteristics stored in Internet packets at the Internet Protocol level). Deep packet inspection is a technique permitted by faster and more sophisticated routers, letting them look at more fine-grained elements of the session and even at application-layer data.
Differentiation by Service (Port, Protocol)
Services such as email, the web, and DNS traffic traditionally use different ports to make it easy to route traffic to the right program, although this is not universally true and some programs deliberately use ports meant for others (especially port 80, which is usually open, at least for incoming traffic, because it is assigned to the Web)
A router can therefore check the port number for a preliminary indication of the traffic being carried. Because programs can use other programs' ports and the port numbers indicate nothing about the actual traffic going between services, deep packet inspection is often used to determine the type of service in use.
For instance, many ISPs want to detect Voice over IP for a variety of reasons: to give its packets a higher privilege because it's a streaming service and therefore subject ot jitter, to block the service because the ISP considers it a competitor to its own voice service, or to offer surveillance to law enforcement. Voice over IP tends to use many ports, often including port 80. Therefore, it is usually detected by building into the router a sophisticated understanding of its protocols. A protocol includes various standard forms of data at the start or end of a message (headers and footers), as well as a strict set of messages exchanged to start, end, or manage a session.
Differentiation by Origin or Destination (IP address)
Differentiation by Volume or Density of Traffic
Ban on "Servers"
Types of Internet Control Not Covered in This Document
Several types of intervention in Internet traffic are not covered in this document because they are related only in indirect ways to the central ISP business issues expressed in the network neutrality debate.
ISPs do not take on the task of detecting and stopping the unauthorized transfer of copyrighted material, such as P2P file sharing of videos and music recordings. However, copyright holders often demand cooperation from ISPs in stopping transfers or catching the parties involved, and use techniques related to the ones described in this paper, notably detecting transfers and using IP addresses to identify the party at one end. Furthermore, ISPs often cite the use of high-volume data transfers and P2P file sharing for illegal purposes as justification for traffic control.
Many of the techniques used to detect various types of transfers for business purposes can also be used for censorship, along with even more sophisticated techniques. For instance, governments often block access to IP addresses associated with news sources they disapprove of, or services used to proxy and hide data transfers.
The techniques in this document are often used by ISPs to support efforts by law enforcement to detect criminals or other people they want to track for any reason.