In March 2019, in a move described in one news report as a “government-imposed Internet shutdown,” the president of Sri Lanka temporarily blocked Facebook, WhatsApp, Instagram, Viber, and other services. In this case, limited access to a class of applications was inaccurately painted as a full-scale Internet shutdown. Unfortunately, this isn’t unusual. Media coverage and general discussion of Internet disruptions often misclassify what happened. The confusion is likely unintentional. Many journalists, as well as the general public, are not well-versed in the various ways Internet access and access to content can be disrupted.

When people can’t get to their favorite social media site, chat app, or video platform, there can be many causes. Maybe there’s a local Internet outage, or access to these sites has been blocked because of a government decree, or a nationwide Internet shutdown has been ordered by the government. Internet disruptions can take several forms, but end users experience the same problem across all of them – an inability to use the Internet to communicate and access content.

If, in the end, the end user experience is the same, why is it important to delineate between the various types of Internet disruptions? Proper delineation can help ensure that coverage and discussion of such events are technically accurate, driving the appropriate actions intended to mitigate or eliminate future disruptions, including policymaking, increased investment, and network infrastructure improvement. A greater understanding of the differences can also help civil society organizations, technical communities, and those affected respond to the disruption appropriately. Responses may range from an acknowledgement that a disruption occurred to increasing global awareness of the current situation to active organization of protests and identification of alternate methods of connectivity, but the response should be commensurate with the scope of the disruption.

Here are different types of disruptions, including why they occur and how they are implemented:

Internet Outages

Outages are arguably the most common type of Internet disruption, resulting from an unintentional or accidental disruption to Internet connectivity at a local, network provider, or national scale. The most frequent root causes of outages include physical damage to fiber/cable, severe weather, power outages, or routing misconfigurations. Outages may also occur as a result of DDoS attacks against core network infrastructure components. These events are generally transient in nature, lasting for minutes or hours.

Content Blocking

Content blocking is an intentional disruption of access to a specific site/application (e.g., Twitter, WhatsApp, Wikipedia) or set of sites/applications (e.g., messaging tools, social media). The blocking is often politically motivated, intended to limit the ability of citizen groups to organize protests, or to prevent dissemination of certain information. Access to other types of content (e-commerce sites, financial services, e-government, etc.) may remain available. There are several ways content blocking can be implemented, including blocking of specific IP addresses/prefixes, URLs, or protocols; filtering through deep packet inspection (DPI); search engine manipulation; or DNS modification. Internet Society Perspectives on Internet Content Blocking: An Overview includes more details.

Throttling

In the context of Internet disruptions, throttling is an intentional slowing of end-user Internet access. It is done with the intent of making the Internet effectively unusable for media and information consumption and sharing. Because Internet access remains available, throttling is harder to detect than other types of disruptions, especially since the impact can be hard to distinguish from network congestion. Throttling on mobile networks can be done by downgrading 3G and 4G connections to 2G, reducing speeds to well under 1 Mbps. Fixed network and application-level throttling can be achieved through the use of traffic management systems installed within a network provider’s infrastructure.

Sub-National Shutdown

Sub-National or localized shutdowns are an intentional disabling of fixed and/or mobile Internet connectivity (or general telecommunications services) around a venue (e.g., stadium), in a city, or at a state/regional level. These more targeted Internet disruptions are generally government directed, are often claimed to be for security reasons (e.g., to prevent remote detonation of explosives by cell phone), or are politically motivated to limit the ability of citizen groups to organize or prevent dissemination of certain information. The easiest way to implement such localized shutdowns of mobile or fixed connectivity is through configuration changes. These changes can effectively disable telecommunications services without having to power down or physically damage the underlying infrastructure, and can prevent the routing of Internet traffic to/from a local network provider. Sub-national shutdowns are often long-lived, lasting for weeks or months.

National Shutdown

A national shutdown is an intentional government-directed disconnection of Internet infrastructure, within a given country, from the global Internet. This is often done through central control of international connectivity. These nationwide Internet shutdowns are usually politically motivated, done to limit the ability of citizen groups to organize or to prevent dissemination of certain information. They have also been used in an attempt to prevent student cheating on national exams. In countries where connectivity to the global Internet relies on a state-controlled telecommunications provider, that provider can remove its entries from the global routing table and drop its connections with international network providers, effectively isolating it. This type of shutdown can be implemented almost immediately. In countries with greater Internet resiliency, each network provider with international connectivity would need to individually withdraw its routing information and drop its connections with international network providers. This type of shutdown could take several hours to implement. Depending on the underlying motivation, national shutdowns may last for a few hours or for multiple days.

What You Can Do

Read the updated Public Policy Brief on Internet Shutdowns, which highlights the impact of Internet shutdowns on local people, economy, and infrastructure and provides guidance to policymakers considering an Internet shutdown. Understanding the different types of Internet disruptions can make us strong advocates to help reduce the number of shutdowns and outages around the world. We become stronger advocates through more educated discourse, better informed solution development, and a greater ability to educate key constituents.

For more information on Internet shutdowns as they occur, please follow Internet Society partners including Netblocks (@netblocks), CAIDA IODA (@caida_ioda), and Oracle Internet Intelligence (@InternetIntel).

Keep the Internet on, and strong. Read the Internet Society Position on Internet Shutdowns.