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 that use a lot of bandwidth in a sustained manner can have trouble cohabiting the lines with other traffic. Voice over IP used to fall into this category, although no the protocols have reduced its demands and the bandwidth in most places has increased to the point where it is not a problem, and streaming video has replaced it as a concern. Streaming media such as voice and video are the high-bandwidth transfes that concern both users and ISPs, because any delays except the most minor ones introduce noticeable problems such as jitter, hanging, and indecipherable voice content. Non-streaming services simply take longer to transmit material, but users often don't notice.
By detecting streams and giving them higher bandwidth, ISPs can provide a more desirable service. Differentiation can be accomplished by directing the streams onto different lines reserved for high-priority traffic or by privileging the packets over other traffic. Customers have traditionally reserved high-priority lines and paid extra. Using the same lines would allow an ISP more fine control and more options in offering enhanced services and charging higher revenue for them.
Potentially, if specialized new services become popular (telemedicine and long-distance education are often cited), the ISP can provide the high bandwidth needed for the services and charge the users on one or both ends. If the provider of the service is charged, the charge would presumably be reflected in service fees.
On the other hand, some ISPs have seen VoIP and video streaming as competition, particularly when the ISP is offered by a company that also offers telephone service of cable TV. Thus, these ISPs have been known to ban VoIP or video streaming and take steps to detect and block them.
Although most Internet services have traditionally been offered to individual end-users for free (or more likely, with embedded advertising to pay for them), businesses have paid for Software as a Service for some time, and there is a trend toward end-user services charging subscription fees, such as some journalistic sites. The popg fularity of services running on mobile devices provides another opportunity for user fees to be introduced on the Internet. Differentiation by ISPs (especially mobile companies) among services allow them to charge for a service and perhaps share the revenue with the site providing the service.
From the beginning of the network neutrality debate, phone and cable companies have claimed that charging for Internet service--usually, charging the provider rather than the end-user--is necessary to provide the funds to bring higher bandwidth to areas that are currently underserved. Differentiated service is seen as a way to promote innovation in networks. In addition to allowing phone and cable companies to differentiate themselves--one perhaps being seen as a friendly site for games, another for telemedicine, etc.--it can also help Internet sites to differentiate themselves on the application layer. For instance, one Internet site can offer faster access to its content by paying for higher bandwidth.
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). Thus, although peer-to-peer file transfers could be considered a distinct service, the programs do not use well-known ports and must be detected in other ways.
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 introduces more variability into a network whose behavior is already unpredictable. Network administrators trying to allocate routing equipment and resources will find their plans frustrated by traffic shaping upstream by ISPs.
- Deep packet inspection introduces more delay overall, although the delay should be absorbed by the ISP doing the inspection by installing faster routers.
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.