Editing Internet backbone

{{Short description|Vital infrastructure of the networks of the Internet}}
{{Use American English|date=January 2019}}
[[File:Internet map 1024.jpg|thumb|right|242x242px|Each line is drawn between two nodes, representing two [[IP address]]es. This is a small look at the backbone of the Internet.]]

The '''Internet backbone''' is the [[backbone network|principal data routes]] between large, strategically interconnected [[computer network]]s and [[core router]]s of the [[Internet]]. These data routes are hosted by commercial, government, academic and other high-capacity network centers as well as the [[Internet exchange point]]s and [[network access point]]s, which exchange Internet traffic internationally. [[Internet service provider]]s (ISPs) participate in Internet backbone traffic through privately negotiated [[Interconnect agreement|interconnection agreements]], primarily governed by the principle of settlement-free [[peering]].

The Internet, and consequently its backbone networks, do not rely on central control or coordinating facilities, nor do they implement any global network policies. The [[Resilience (network)|resilience]] of the Internet results from its principal architectural features, such as the idea of placing as few network [[State (computer science)|state]] and control functions as possible in the network elements, instead relying on the endpoints of communication to handle most of the processing to ensure data integrity, reliability, and authentication. In addition, the high degree of [[Redundancy (engineering)|redundancy]] of today's network links and sophisticated real-time [[routing]] protocols provide alternate paths of communications for [[Load balancing (computing)|load balancing]] and congestion avoidance.

The largest providers, known as [[Tier 1 network|Tier 1 networks]], have such comprehensive networks that they do not purchase [[Internet transit|transit]] agreements from other providers.<ref name="crossroads" />

==Infrastructure==
[[File:Submarine cable map umap.png|alt=Undersea Internet cables|thumb|270x270px|Routing of prominent undersea cables that serve as the physical infrastructure of the Internet.]]

The Internet backbone consists of many networks owned by numerous companies. 

[[Fiber-optic communication]] remains the medium of choice for Internet backbone providers for several reasons. Fiber-optics allow for fast data speeds and large [[Bandwidth (signal processing)|bandwidth]], suffer relatively little [[attenuation]] — allowing them to cover long distances with few [[repeater]]s — and are immune to [[crosstalk]] and other forms of electromagnetic interference.{{citation needed|date=January 2021}} 

The real-time routing protocols and redundancy built into the backbone is also able to reroute traffic in case of a failure.<ref>{{Cite book|last=Nuechterlein, Jonathan E., author.|title=Digital crossroads: telecommunications law and policy in the internet age|date=5 July 2013|publisher=MIT Press |isbn=978-0-262-51960-1|oclc=827115552}}</ref> The data rates of backbone lines have increased over time. In 1998,<ref>{{Cite SSRN |last1=Kesan|first1=Jay P.|last2=Shah|first2=Rajiv C.|date=2002|title=Shaping Code|ssrn=328920}}</ref> all of the United States' backbone networks had utilized the slowest data rate of 45 Mbit/s. However, technological improvements allowed for 41 percent of backbones to have [[Data signaling rate|data rates]] of 2,488&nbsp;Mbit/s or faster by the mid 2000s.<ref>{{Cite journal|last=Malecki|first=Edward J.|date=October 2002|title=The Economic Geography of the Internet's Infrastructure|journal=Economic Geography|volume=78|issue=4|pages=399–424|doi=10.2307/4140796|jstor=4140796|issn=0013-0095}}</ref>

==History==
{{more|History of the Internet}}
The first packet-switched computer networks, the [[NPL network]] and the [[ARPANET]] were interconnected in 1973 via [[University College London]].<ref>{{Cite journal|last=Kirstein|first=P.T.|date=1999|title=Early experiences with the Arpanet and Internet in the United Kingdom|url=https://pdfs.semanticscholar.org/4773/f19792f9fce8eacba72e5f8c2a021414e52d.pdf|archive-url=https://web.archive.org/web/20200207092443/https://pdfs.semanticscholar.org/4773/f19792f9fce8eacba72e5f8c2a021414e52d.pdf|url-status=dead|archive-date=2020-02-07|journal=IEEE Annals of the History of Computing|volume=21|issue=1|pages=38–44|doi=10.1109/85.759368|s2cid=1558618|issn=1934-1547}}</ref> The ARPANET used a backbone of routers called [[Interface Message Processor]]s. Other packet-switched computer networks proliferated starting in the 1970s, eventually adopting TCP/IP protocols or being replaced by newer networks. 

The National Science Foundation created the [[National Science Foundation Network]] (NSFNET) in 1986 by funding six networking sites using {{gaps|56|kbit/s}} interconnecting links, with peering to the ARPANET. In 1987, this new network was upgraded to {{gaps|1.5|Mbit/s}} [[T-carrier|T1]] links for thirteen sites. These sites included regional networks that in turn connected over 170 other networks. [[IBM]], [[MCI Communications|MCI]] and [[Merit Network|Merit]] upgraded the backbone to {{gaps|45|Mbit/s}} bandwidth ([[T-carrier|T3]]) in 1991.<ref>{{cite journal|last=Kende|first=M.|title=The Digital Handshake: Connecting Internet Backbones|journal=Journal of Communications Law & Policy|year=2000|volume=11|pages=1–45}}</ref> The combination of the ARPANET and NSFNET became known as the Internet. Within a few years, the dominance of the NSFNet backbone led to the decommissioning of the redundant ARPANET infrastructure in 1990.

In the early days of the Internet, backbone providers exchanged their traffic at government-sponsored [[network access point]]s (NAPs), until the government privatized the Internet and transferred the NAPs to commercial providers.<ref name="crossroads">{{cite book|title=Digital Crossroads|url=https://archive.org/details/digitalcrossroad00jona|url-access=registration|author=Jonathan E. Nuechterlein|author2=Philip J. Weiser|year=2005 |publisher=MIT Press |isbn=9780262140911 }}</ref>

==Modern backbone==
{{Globalize|section|date=September 2011}}
Because of the overlap and synergy between long-distance telephone networks and backbone networks, the largest long-distance voice carriers such as [[AT&T|AT&T Inc.]], [[Verizon Communications|Verizon]], [[Sprint Corporation|Sprint]], and [[Lumen Technologies|Lumen]] also own some of the largest Internet backbone networks. These backbone providers sell their services to Internet service providers.<ref name=crossroads />

Each ISP has its own contingency network and is equipped with an outsourced backup. These networks are intertwined and crisscrossed to create a redundant network. Many companies operate their own backbones which are all interconnected at various [[Internet exchange point]]s around the world.<ref>{{cite web|last=Tyson|first=J.|title=How Internet Infrastructure Works|date=3 April 2001 |url=http://computer.howstuffworks.com/internet/basics/internet-infrastructure4.htm|access-date=9 February 2011|url-status=live|archive-url=https://web.archive.org/web/20110614002356/http://computer.howstuffworks.com/internet/basics/internet-infrastructure4.htm|archive-date=14 June 2011}}</ref> In order for data to navigate this web, it is necessary to have backbone routers—[[Router (computing)|routers]] powerful enough to handle information—on the Internet backbone that are capable of directing data to other routers in order to send it to its final destination. Without them, information would be lost.<ref>{{cite journal|last=Badasyan|first=N.|author2=Chakrabarti, S.|title=Private peering, transit and traffic diversion|journal=Netnomics: Economic Research and Electronic Networking|year=2005|volume=7|issue=2|pages=115|doi=10.1007/s11066-006-9007-x|s2cid=154591220}}</ref>

==Economy of the backbone==
===Peering agreements===
Backbone providers of roughly equivalent market share regularly create agreements called [[Peering#Peering agreement|peering agreements]], which allow the use of another's network to hand off traffic where it is ultimately delivered. Usually they do not charge each other for this, as the companies get revenue from their customers.<ref name=crossroads /><ref name=topbits>{{cite web|title=Internet Backbone|url=http://www.tech-faq.com/internet-backbone.html|publisher=Topbits Website|access-date=9 February 2011|url-status=live|archive-url=https://web.archive.org/web/20110716200149/http://www.tech-faq.com/internet-backbone.html|archive-date=16 July 2011}}</ref>

===Regulation===
[[Competition law|Antitrust]] authorities have acted to ensure that no provider grows large enough to dominate the backbone market. In the United States, the [[Federal Communications Commission]] has decided not to monitor the competitive aspects of the Internet backbone interconnection relationships as long as the market continues to function well.<ref name="crossroads" />

===Transit agreements===
Backbone providers of unequal market share usually create agreements called [[Internet transit|transit agreements]], and usually contain some type of monetary agreement.<ref name=crossroads /><ref name=topbits />

==Regional backbone==

===Egypt===
During the [[2011 Egyptian revolution]], the government of [[Egypt]] shut down the four major ISPs on January&nbsp;27,&nbsp;2011 at approximately 5:20&nbsp;p.m.&nbsp;EST.<ref name=wired>{{cite magazine|last=Singel|first=Ryan|title=Egypt Shut Down Its Net With a Series of Phone Calls|url=https://www.wired.com/threatlevel/2011/01/egypt-isp-shutdown/|magazine=Wired|access-date=30 April 2011|date=28 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110501183804/http://www.wired.com/threatlevel/2011/01/egypt-isp-shutdown|archive-date=1 May 2011}}</ref> The networks had not been physically interrupted, as the Internet transit traffic through Egypt was unaffected. Instead, the government shut down the [[Border Gateway Protocol]]&nbsp;(BGP) sessions announcing local routes. BGP is responsible for routing traffic between ISPs.<ref>{{cite web|last=Van Beijnum|first=Iljitsch|title=How Egypt did (and your government could) shut down the Internet|url=https://arstechnica.com/tech-policy/news/2011/01/how-egypt-or-how-your-government-could-shut-down-the-internet.ars|website=Ars Technica|date=30 January 2011 |access-date=30 April 2011|url-status=live|archive-url=https://web.archive.org/web/20110426155523/http://arstechnica.com/tech-policy/news/2011/01/how-egypt-or-how-your-government-could-shut-down-the-internet.ars|archive-date=26 April 2011}}</ref>

Only one of Egypt's ISPs was allowed to continue operations. The ISP Noor Group provided connectivity only to Egypt's stock exchange as well as some government ministries.<ref name=wired /> Other ISPs started to offer free dial-up Internet access in other countries.<ref>{{cite web|last=Murphy|first=Kevin|title=DNS not to blame for Egypt blackout|date=28 January 2011 |url=http://domainincite.com/dns-not-to-blame-for-egypt-blackout/|publisher=Domain Incite|access-date=30 April 2011|url-status=live|archive-url=https://web.archive.org/web/20110404013457/http://domainincite.com/dns-not-to-blame-for-egypt-blackout/|archive-date=4 April 2011}}</ref>

===Europe===
[[Europe]] is a major contributor to the growth of the international backbone as well as a contributor to the growth of Internet bandwidth. In 2003, Europe was credited with 82 percent of the world's international cross-border bandwidth.<ref>{{cite journal|title=Global Internet backbone back up to speed for 2003 after dramatic slow down in 2002|journal=TechTrends|year=2003|volume=47|issue=5|pages=47}}</ref> The company [[Level&nbsp;3 Communications]] began to launch a line of dedicated Internet access and [[virtual private network]] services in 2011, giving large companies direct access to the tier&nbsp;3 backbone. Connecting companies directly to the backbone will provide enterprises faster Internet service which meets a large market demand.<ref>{{cite news|title=Europe - Level 3 launches DIA, VPN service portfolios in Europe|newspaper=Europe Intelligence Wire|date=28 January 2011}}</ref>

===Caucasus===
Certain countries around the [[Caucasus]] have very simple backbone networks. In 2011, a 75-year-old woman in [[Georgia (country)|Georgia]] pierced a [[Optical fiber|fiber backbone]] line with a shovel and left the neighboring country of [[Armenia]] without Internet access for 12 hours.<ref>{{cite news|last=Lomsadze|first=Giorgi|title=A Shovel Cuts Off Armenia's Internet|url=https://www.wsj.com/articles/SB10001424052748704630004576249013084603344|access-date=16 April 2011|newspaper=The Wall Street Journal|date=8 April 2011|url-status=live|archive-url=https://web.archive.org/web/20141225063937/http://www.wsj.com/articles/SB10001424052748704630004576249013084603344|archive-date=25 December 2014}}</ref>  The country has since made major developments to the fiber backbone infrastructure, but progress is slow due to lack of government funding. {{Citation needed|reason=The source that is linked above does not have information on subsequent infrastructure updates|date=March 2025}}

===Japan===
[[Japan]]'s internet backbone requires a high degree of efficiency to support high demand for the Internet and technology in general. Japan had over 86&nbsp;million Internet users in 2009, and was projected to climb to nearly 91&nbsp;million Internet users by&nbsp;2015. Since Japan has a demand for fiber to the home, Japan is looking into tapping a [[Fiber-optic communication|fiber-optic]] backbone line of [[Nippon Telegraph and Telephone]]&nbsp;(NTT), a domestic backbone carrier, in order to deliver this service at cheaper prices.<ref>{{cite journal|title=Japan telecommunications report - Q2 2011|journal=Japan Telecommunications Report|year=2011|issue=1}}</ref>

=== China ===
In some instances, the companies that own certain sections of the Internet backbone's physical infrastructure depend on competition in order to keep the Internet market profitable. This can be seen most prominently in [[China]]. Since [[China Telecommunications Corporation|China Telecom]] and [[China Unicom]] have acted as the sole Internet service providers to China for some time, smaller companies cannot compete with them in negotiating the interconnection settlement prices that keep the Internet market profitable in China. This imposition of discriminatory pricing by the large companies then results in market inefficiencies and stagnation, and ultimately affects the efficiency of the Internet backbone networks that service the nation.<ref>{{Cite journal|last1=Li|first1=Meijuan|last2=Zhu|first2=Yajie|date=2018|title=Research on the problems of interconnection settlement in China's Internet backbone network|journal=Procedia Computer Science|volume=131|pages=153–157|doi=10.1016/j.procs.2018.04.198|doi-access=free}}</ref>

==See also==
{{Portal|Internet}}
* [[Default-free zone]]
* [[Internet2]]
* [[Mbone]]
* [[Network service provider]]
* [[Root name server]]
* [[Packet switching]]
* [[Trunking]]

==Further reading==

* Greenstein, Shane. 2020. "[https://www.aeaweb.org/articles?id=10.1257/jep.34.2.192 The Basic Economics of Internet Infrastructure.]" ''Journal of Economic Perspectives'', 34 (2): 192-214. DOI: 10.1257/jep.34.2.192

==References==
{{reflist}}

== Further reading ==
* {{Cite news |last=Dzieza |first=Josh |date=2024-04-16 |title=The cloud under the sea: The invisible seafaring industry that keeps the internet afloat |url=https://www.theverge.com/c/24070570/internet-cables-undersea-deep-repair-ships |access-date=2024-04-16 |website=The Verge}}

==External links==
{{commons category|Maps of Internet backbone networks}}
* [http://www.level3.com/en/about-us/ About Level 3]
* [http://navigators.com/isp.html Russ Haynal's ISP Page]
* [https://web.archive.org/web/20060411203358/http://www.nthelp.com/maps.htm US Internet backbone maps]
* [http://www.opte.org/maps/ Automatically generated backbone map of the Internet] {{Webarchive|url=https://web.archive.org/web/20191009053255/http://www.opte.org/maps/ |date=2019-10-09 }}
* [https://web.archive.org/web/20181028124233/http://ipv6.nlsde.buaa.edu.cn/ IPv6 Backbone Network Topology]

[[Category:Internet architecture|Backbone, Internet]]
[[Category:IT infrastructure]]