Bandwidth throttling consists in the limitation of the communication speed (bytes or kilobytes per second), of the ingoing (received) or outgoing (sent) data in a network node or in a network device such as computers and mobile phones.

The data speed and rendering may be limited depending on various parameters and conditions.


Limiting the speed of data sent by a data originator (a client computer or a server computer) is much more efficient than limiting the speed in an intermediate network device between client and server because while in the first case usually no network packets are lost, in the second case network packets can be lost / discarded whenever ingoing data speed overcomes the bandwidth limit or the capacity of device and data packets cannot be temporarily stored in a buffer queue (because it is full or it does not exist); the usage of such a buffer queue is to absorb the peaks of incoming data for very short time lapse.

In the second case discarded data packets can be resent by transmitter and received again.

When a low level network device discards incoming data packets usually can also notify that fact to data transmitter in order to slow down the transmission speed (see also network congestion).[1]

NOTE: Bandwidth throttling should not be confused with rate limiting which operates on client requests at application server level and/or at network management level (i.e. by inspecting protocol data packets). Rate limiting can also help in keeping peaks of data speed under control.

These bandwidth limitations can be implemented:

The first one (client/server program) is usually perfectly legal because it is a choice of the client manager or the server manager (by server administrator) to limit or not to limit the speed of data received from remote program via network or the speed of data sent to target program (server or client).

The second one (ISP) instead is considered an offense in the USA under FCC regulations. While ISPs prey on the individual's inability to fight them, fines can range up to $25,000 USD for throttling. In the United States, net neutrality, the principle that Internet service providers (ISPs) treat all data on the Internet the same, and not discriminate, has been an issue of contention between network users and access providers since the 1990s. With net neutrality, ISPs may not intentionally block, slow down, or charge money for specific online content.

Defined as the intentional slowing or speeding of an internet service by an Internet service provider (ISP). It is a reactive measure employed in communication networks to regulate network traffic and minimize bandwidth congestion. Bandwidth throttling can occur at different locations on the network. On a local area network (LAN), a system administrator ("sysadmin") may employ bandwidth throttling to help limit network congestion and server crashes. On a broader level, the Internet service provider may use bandwidth throttling to help reduce a user's usage of bandwidth that is supplied to the local network. Bandwidth throttling is also used as a measurement of data rate on Internet speed test websites.

Throttling can be used to actively limit a user's upload and download rates on programs such as video streaming, BitTorrent protocols and other file sharing applications, as well as even out the usage of the total bandwidth supplied across all users on the network. Bandwidth throttling is also often used in Internet applications, in order to spread a load over a wider network to reduce local network congestion, or over a number of servers to avoid overloading individual ones, and so reduce their risk of the system crashing, and gain additional revenue by giving users an incentive to use more expensive tiered pricing schemes, where bandwidth is not throttled.


A computer network typically consists of a number of servers, which host data and provide services to clients. The Internet is a good example, in which web servers are used to host websites, providing information to a potentially very large number of client computers. Clients will make requests to servers, which will respond by sending the required data, which may be a song file, a video, and so on, depending on what the client has requested. As there will typically be many clients per server, the data processing demand on a server will generally be considerably greater than on any individual client. And so servers are typically implemented using computers with high data capacity and processing power. The traffic on such a network will vary over time, and there will be periods when client requests will peak or sent responses will be huge, sometimes exceeding the capacity of parts of network and causing congestion, especially in parts of the network that form bottlenecks. This can cause data request failures, or in worst cases, server crashes.

In order to prevent such occurrences, a client / server / system administrator may enable (if available) bandwidth throttling:

examples: assuming to have a server site with speed access to Internet of 100MB/s (around 1000Mbit/s), assuming that most clients have a 1 MB/s (around 10 Mbit/s) network speed access to Internet and assuming to be able to download huge files (i.e. 1 GB each):
  • with bandwidth throttling, a server using a max. output speed of 100kB/s (around 1 Mbit/s) for each TCP connection, could allow at least 1000 active TCP connections (or even 10000 if output is limited to 10 kB/s) (active connections means that data content, such as a big file, is being downloaded from server to client);
  • without bandwidth throttling, a server could efficiently serve only 100 active TCP connections (100 MB/s / 1 MB/s) before saturating network bandwidth; a saturated network (i.e. with a bottleneck through an Internet Access Point) could slow down a lot the attempts to establish other new connections or even to force them to fail because of timeouts, etc.; besides this new active connections could not get easily or fastly their proper share of bandwidth.


A bandwidth intensive device, such as a server, might limit (throttle) the speed at which it receives or sends data, in order to avoid overloading its processing capacity or to saturate network bandwidth. This can be done both at the local network servers or at the ISP servers. ISPs often employ deep packet inspection (DPI), which is widely available in routers or provided by special DPI equipment. Additionally, today's networking equipment allows ISPs to collect statistics on flow sizes at line speed, which can be used to mark large flows for traffic shaping.[2] Two ISPs, Cox and Comcast, have stated that they engage in this practice, where they limit users' bandwidth by up to 99%.[3] Today most if not all Internet Service Providers throttle their users' bandwidth, with or without the user ever even realizing it.[4] In the specific case of Comcast, an equipment vendor called Sandvine developed the network management technology that throttled P2P file transfers.[5]

Those that could have their bandwidth throttled are typically someone who is constantly downloading and uploading torrents, or someone who just watches a lot of online videos. If this is done by an ISP, many consider this practice as an unfair method of regulating the bandwidth because consumers are not getting the required bandwidth even after paying the prices set by the ISPs. By throttling the people who are using so much bandwidth, the ISPs claim to enable their regular users to have a better overall quality of service.[6]

Network neutrality

Net neutrality is the principle that all Internet traffic should be treated equally. It aims to guarantee a level playing field for all websites and Internet technologies. With net neutrality, the network's only job is to move data—not to choose which data to privilege with higher quality, that is faster, service. In the US, on February 26, 2015, the Federal Communications Commission adopted Open Internet rules. They are designed to protect free expression and innovation on the Internet and promote investment in the nation's broadband networks. The Open Internet rules are grounded in the strongest possible legal foundation by relying on multiple sources of authority, including: Title II of the Communications Act and Section 706 of the Telecommunications Act of 1996. The new rules apply to both fixed and mobile broadband services.[7] However, these rules were rolled back on December 14, 2017.

Bright line rules:

Throttling vs. capping

Bandwidth throttling works by limiting (throttling) the speed at which a bandwidth intensive device (a server) receives data or the speed (i.e. bytes / kilobytes per second) of each data response. If these limits are not in place, the device can overload its processing capacity.

Contrary to throttling, in order to use bandwidth when available, but prevent excess, each node in a proactive system should set an outgoing bandwidth cap that appropriately limits the total number of bytes sent per unit time.[8] There are two types of bandwidth capping. A standard cap limits the bitrate or speed of data transfer on a broadband Internet connection. Standard capping is used to prevent individuals from consuming the entire transmission capacity of the medium. A lowered cap reduces an individual user's bandwidth cap as a defensive measure and/or as a punishment for heavy use of the medium's bandwidth. Oftentimes this happens without notifying the user.

The difference is that bandwidth throttling regulates a bandwidth intensive device (such as a server) by limiting how much data that device can receive from each node / client or can output or can send for each response. Bandwidth capping on the other hand limits the total transfer capacity, upstream or downstream, of data over a medium.

Court cases

Comcast Corp. v. FCC

Main article: Comcast Corp. v. FCC

In 2007, Free Press, Public Knowledge, and the Federal Communications Commission filed a complaint against Comcast's Internet service. Several subscribers claimed that the company was interfering with their use of peer-to-peer networking applications. The Commission stated that it had jurisdiction over Comcast's network management practices and that it could resolve the dispute through negotiation rather than through rulemaking. The Commission believed that Comcast had "significantly impeded consumers' ability to access the content and use the applications of their choice", and that because Comcast "ha[d] several available options it could use to manage network traffic without discriminating" against peer-to-peer communications, its method of bandwidth management "contravene[d] ... federal policy". At this time, "Comcast had already agreed to adopt a new system for managing bandwidth demand, the Commission simply ordered it to make a set of disclosures describing the details of its new approach and the company's progress toward implementing it". Comcast complied with this Order but petitioned for a review and presented several objections.[9]

ISP bandwidth throttling


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In 2008, the Canadian Radio-television and Telecommunications Commission (CRTC) decided to allow Bell Canada to single out peer-to-peer (P2P) traffic for bandwidth throttling between the hours of 4:30 p.m. to 2 a.m.[10] In 2009, the CRTC released a guideline for bandwidth throttling rules.[11]

In 2011, following a major complaint by the Canadian Gamers Organization against Rogers for breaking the 2009 rules already in place, the CRTC created an addendum[12] to their ITMP policy, allowing them to send the complaint to their Enforcements Division. The Canadian Gamers Organization in their submissions alluded to filing a complaint against Bell Canada. On December 20, 2011, Bell Canada announced they would end throttling by March 31, 2012 for their customers, as well as their wholesale customers.[13] On February 4, 2012, in an effort to get out of trouble with the CRTC (which had continued its own testing and had found additional non-compliance and demanded immediate compliance), Rogers announced 50% of their customers would be throttle-free by June 2012, and 100% of their customers would be throttle-free by the end of 2012.[14] Unfortunately for Rogers, this did not mollify the CRTC Enforcements Division.

ISPs in Canada that throttle bandwidth:


In April 2011, the European Union launched an investigation into Internet service providers' methods for managing traffic on their networks. Some ISPs, for instance, restrict access to services such as Skype or the BBC iPlayer at peak times so that their users all receive an equal service. The EU's commissioner for the digital agenda, Neelie Kroes, said: "I am absolutely determined that everyone in the EU should have the chance to enjoy the benefits of an open and lawful Internet, without hidden restrictions or slower speeds than they have been promised." The Body of European Regulators for Electronic Communications (Berec) will examine the issues for the EU, and will ask both businesses and consumers for their views. The EU published the results of its investigation at the end of 2011.[17] New laws mean that ISPs are prohibited from blocking or slowing down of Internet traffic, except where necessary.[18]


In Singapore, net neutrality has been the law since 2011. November 2010, defined by the Infocomm Development Authority (IDA).[19] But despite the law, the majority of the ISPs do throttle bandwidth.

ISPs in Singapore that throttle bandwidth:[20]

ISP Name Limits bandwidth
Starhub Yes
Singtel Yes[21]
M1 Limited Yes
MyRepublic No[22]
Viewqwest No

United States

Parts of this article (those related to FCC net neutrality rules) need to be updated. Please help update this article to reflect recent events or newly available information. (September 2015)

In 2007, Comcast was caught interfering with peer-to-peer traffic. Specifically, it falsified packets of data that fooled users and their peer-to-peer programs into thinking they were transferring files.[23] Comcast initially denied that it interfered with its subscribers' uploads, but later admitted it.[24] The FCC held a hearing and concluded that Comcast violated the principles of the Internet Policy Statement because Comcast's "discriminatory and arbitrary practice unduly squelched the dynamic benefits of an open and accessible Internet and did not constitute reasonable network management."[25] The FCC also provided clear guidelines to any ISP wishing to engage in reasonable network management. The FCC suggested ways that Comcast could have achieved its goal of stopping network congestion, including capping the average user's capacity and charging the most aggressive users overage (going over a maximum) fees, throttling back the connections of all high capacity users, or negotiating directly with the application providers and developing new technologies.[26]

However, in 2008, Comcast amended their Acceptable Usage Policy and placed a specific 250 GB monthly cap. Comcast has also announced a new bandwidth-throttling plan. The scheme includes a two-class system of "priority-best-effort" and "best-effort" where "sustained use of 70% of your up or downstream throughput triggers the BE state, at which point you'll find your traffic priority lowered until your usage drops to 50% of your provisioned upstream or downstream bandwidth for "a period of approximately 15 minutes". A throttled Comcast user being placed in a BE state "may or may not result in the user's traffic being delayed or, in extreme cases, dropped before PBE traffic is dropped". Comcast explained to the FCC that "If there is no congestion, packets from a user in a BE state should have little trouble getting on the bus when they arrive at the bus stop. If, on the other hand, there is congestion in a particular instance, the bus may become filled by packets in a PBE state before any BE packets can get on. In that situation, the BE packets would have to wait for the next bus that is not filled by PBE packets".[27]

US cell phone ISP's have also increasingly resorted to bandwidth throttling in their networks. Verizon and AT&T even applied such throttling to data plans advertised as "unlimited", resulting an FCC complaint against Verizon.[citation needed] Though AT&T had told its customers throttling was a possibility, the FTC filed a lawsuit against the company in 2014, charging that the disclosure was insufficiently specific.[28] A nation-wide study of video streaming speeds in 2018-2019 found major wireless carriers throttling a majority of the time, including when traffic was light, and with significant discrepancies between video services.[29]


Antel has a state-enforced monopoly forcing consumers who require non-wireless Internet access (i.e. ADSL or fiber – cable Internet is outlawed[30]) to purchase it directly from Antel. Its practices provide insight into the probable behavior of ISPs in markets that have little or no competition and/or lack balancing regulations in the interest of consumers. All of Antel's Internet access plans for consumers are either capped or throttled. Capped plans are typically marketed under the brand "flexible". On such plans once a user reaches a data tier (e.g. 5 GB) additional data usage is billed at a rate of approximately $5 US/GB. Once a second tier is reached (e.g., 15 GB), Internet services are suspended until the start of the next billing cycle. Throttled plans are typically marketed under the brand "Flat Rate" (for ADSL) and "Vera" (for fiber.) Such plans allow full bandwidth on the connection (e.g. 20 Mbit/s down on the Vera fiber plan) from the beginning of the billing month but are restricted to a percentage of the contracted transmission rate (e.g., to 2 Mbit/s down, or 10% of the advertised speed) once a data tier (e.g. 150 GB) is reached. Full bandwidth capability is restored at the beginning of the next billing month.[31][32]

Metrics for ISPs

Whether aimed at avoiding network congestion or at pushing users to upgrade to costlier Internet plans, the increasingly common capping and throttling practices of ISPs undoubtedly have an effect on the value proposition of the plans they offer. For consumers to be able to make an informed decision when choosing an Internet plan, ISPs should publish their capping and throttling practices with the necessary level of detail. While the net effect of some throttling and capping strategies can be hard to compare across ISPs, some basic metrics that are of interest for any kind of throttled/capped Internet connection are:

User responses

Although ISPs may actively throttle bandwidth, there are several known methods to bypass the throttling of a user's bandwidth, if the throttling is focused on a particular protocol. These methods, nicknamed "workarounds", include:[33]

See also


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  2. ^ Massimiliano Marcon; et al. "The Local and Global Effects of Traffic Shaping in the Internet" (PDF). MPI. Archived (PDF) from the original on July 22, 2011. Retrieved May 3, 2011.
  3. ^ Max Planck Institute (March 18, 2008). "Glasnost: Results from tests for BitTorrent traffic blocking". Archived from the original on April 4, 2011. Retrieved April 3, 2011.
  4. ^ netequalizer (March 21, 2009). "Is Your ISP Throttling Your Bandwidth?". Archived from the original on April 5, 2011. Retrieved April 3, 2011.
  5. ^ Kevin Werbach (2009). "Higher Standards Regulation in the Network Age". Harvard Journal of Law & Technology. 23 (1). Harvard University: 217. SSRN 1557265.
  6. ^ "What is Internet Throttling? Everything You Need To Know". July 27, 2021. Archived from the original on 2021-08-16. Retrieved July 27, 2021.
  7. ^ a b "Open Internet". Archived from the original on 2015-06-15. Retrieved 2015-06-03.
  8. ^ Emil Sit; Andreas Haeberlen; Frank Dabek; Byung-Gon Chun; Hakim Weatherspoon; Robert Morris; M. Frans Kaashoek; John Kubiatowicz. Proactive replication for data durability. p. 6. CiteSeerX
  9. ^ Comcast vs. FCC & U.S., 08-1291 Chief Judge David S. Tatel (United States Court of Appeals for the District of Columbia April 6, 2010).
  10. ^ Anderson, Nate (20 November 2008). "Canadian regulators allow P2P throttling". Ars Technica. Archived from the original on 25 March 2011. Retrieved April 3, 2011.
  11. ^ "Telecom Regulatory Policy CRTC 2009-657". CRTC. 2009. Archived from the original on July 12, 2012. Retrieved April 21, 2012.
  12. ^ "Internet traffic management practices – Guidelines for responding to complaints and enforcing framework compliance by Internet service providers". CRTC. 2011. Archived from the original on July 12, 2012. Retrieved April 21, 2012.
  13. ^ "Bell to stop internet throttling". CBC News. 2011. Archived from the original on April 19, 2012. Retrieved April 21, 2012.
  14. ^ "Rogers promises to end internet throttling". CBC News. 2012. Archived from the original on April 27, 2012. Retrieved April 21, 2012.
  15. ^ "Bell Canada ends internet throttling in favor of usage-based billing". The Verge. 23 December 2011. Retrieved 8 November 2019. ISP Bell Canada has announced that it will stop throttling peer-to-peer file-sharing next year
  16. ^ a b "Sunwire Support FAQ".
  17. ^ Matt Warman (April 20, 2011). "EU launches net neutrality investigation". The Telegraph. London. Archived from the original on April 26, 2011. Retrieved May 3, 2011.
  18. ^ "All you need to know about Net Neutrality rules in the EU | BEREC".
  19. ^ "NET NEUTRALITY" (PDF). Archived from the original (PDF) on 2015-07-21. Retrieved 28 April 2015.
  20. ^ "Bad ISPs". Archived from the original on 28 April 2015. Retrieved 28 April 2015.
  21. ^ "Does SingNet perform any network management activities?". Archived from the original on 26 March 2015. Retrieved 28 April 2015.
  22. ^ "Does MyRepublic throttle BitTorrent / P2P traffic?". Archived from the original on 4 March 2016. Retrieved 28 April 2015.
  23. ^ Peter Svensson (2007-10-19). "Comcast blocks some Internet traffic". Associated Press. Retrieved May 3, 2011.
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  26. ^ Michael P. Murtagh (2008). "The FCC, the DMCA, and Why Takedown Notices Are Not Enough" (PDF). Hastings Law Journal. 61 (233). University of California: 242–243. Archived from the original (PDF) on 2011-09-27. Retrieved 2011-05-03.
  27. ^ Karl Bode (January 5, 2009). "New Comcast Throttling System 100% Online". Archived from the original on August 10, 2011. Retrieved March 14, 2011.
  28. ^ Edward Wyatt (October 28, 2014). "AT&T Accused of Deceiving Smartphone Customers With Unlimited Data Plans". The New York Times. Archived from the original on October 29, 2014. Retrieved October 29, 2014.
  29. ^ Wireless carrier throttling of online video is pervasive
  30. ^ Only Cuba and Uruguay don't offer Internet access via cable modem (In Spanish) Archived 2013-05-14 at the Wayback Machine
  31. ^ Telecommunications in Uruguay
  32. ^ Planes de Internet – Antel
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  34. ^ "Optimize BitTorrent to outwit traffic shaping ISPs". Archived from the original on November 7, 2012. Retrieved April 26, 2011.