Editing Tier 1 network

{{Short description|Top level network on the internet}}
{{Use American English|date=January 2019}}
A '''Tier 1 network''' is an [[Internet Protocol]] (IP) network that can reach every other network on the [[Internet]] solely via settlement-free interconnection (also known as settlement-free [[peering]]).<ref name="IDC">{{cite web|url = http://www.us.ntt.net/downloads/papers/IDC_Tier1_ISPs.pdf|title = Tier1 ISPs: What They Are and Why They Are Important|date = May 2006|website = NTT America Corporate|last = Winther|first = Mark| archive-url=https://web.archive.org/web/20100803003541/http://www.us.ntt.net/downloads/papers/IDC_Tier1_ISPs.pdf | archive-date=2010-08-03 }}</ref><ref name="ARS">{{cite web|url=https://arstechnica.com/guides/other/peering-and-transit.ars/4|title=How the 'Net works: an introduction to peering and transit: Page 4|access-date=2008-11-04|date=2008-09-02|quote=Tier 1 networks are those networks that don't pay any other network for transit yet still can reach all networks connected to the internet.}}</ref> Tier 1 networks can exchange traffic with other Tier 1 networks without paying any fees for the exchange of traffic in either direction.<ref name=pcmag>{{cite web|url=https://www.pcmag.com/encyclopedia/term/60763/tier-1-network|title=Definition of: Tier 1 network |website=pcmag.com |access-date=2018-08-10}}</ref> In contrast, some [[Tier 2 network]]s and all Tier 3 networks must pay to transmit traffic on other networks.<ref name=pcmag/> [[File:Internet Connectivity Distribution & Core.svg|right|thumb|upright=2.5|Relationship between the various tiers of Internet providers]]
There is no authority that defines tiers of networks participating in the Internet.<ref name="IDC" /> The most common and well-accepted definition of a Tier 1 network is a network that can reach every other network on the [[Internet]] without purchasing [[Internet transit|IP transit]] or paying for peering.<ref name="ARS" /> By this definition, a Tier 1 network must be a [[Internet transit|transit-free network]] (purchases no transit) that peers for no charge with every other Tier 1 network<ref>{{cite book | url=https://books.google.com/books?id=fTPmJytNeosC&dq=tier+1+network&pg=PA10 | title=Alcatel-Lucent Scalable IP Networks Self-Study Guide: Preparing for the Network Routing Specialist I (NRS 1) Certification Exam | isbn=978-0-470-52938-6 | last1=Hundley | first1=Kent | date=31 August 2009 | publisher=John Wiley & Sons }}</ref><ref>{{cite book | url=https://books.google.com/books?id=92ZYiSTXkWMC&dq=tier+1+peering&pg=PT113 | title=The Internet Peering Playbook: Connecting to the Core of the Internet | isbn=978-1-937451-02-8 | last1=Norton | first1=William B. | date=8 August 2011 | publisher=DrPeering Press }}</ref> and can reach all major networks on the Internet. Not all transit-free networks are Tier 1 networks, as it is possible to become transit-free by paying for peering, and it is also possible to be transit-free without being able to reach all major networks on the Internet.

The most widely quoted source for identifying Tier 1 networks is published by Renesys Corporation, but the base information to prove the claim is publicly accessible from many locations, such as the RIPE RIS database,<ref>[http://www.ripe.net/ris/ RIPE RIS database]</ref> the Oregon [[Route Views]] servers, [[Packet Clearing House]], and others.

It can be difficult to determine whether a network is paying for peering or transit, as these business agreements are rarely public information, or are covered under a [[non-disclosure agreement]]. The Internet peering community is roughly the set of peering coordinators present at the [[Internet exchange point]]s on more than one continent. The subset representing Tier 1 networks is collectively understood in a loose sense, but not published as such.

Common definitions of Tier 2 and Tier 3 networks:
* [[Tier 2 network]]: A network that peers for no charge with some networks, but still purchases IP transit or pays for peering to reach at least some portion of the Internet.
* Tier 3 network: A network that solely purchases transit/peering from other networks to participate in the Internet.

==History==
The original [[Internet backbone]] was the [[ARPANET]] when it provided the routing between most participating networks. The development of the British [[JANET]] (1984) and U.S. [[National Science Foundation Network|NSFNET]] (1985) infrastructure programs to serve their nations' higher education communities, regardless of discipline,<ref name="internetsociety.org">{{cite web|url=https://www.internetsociety.org/internet/history-internet/brief-history-internet/|title=Brief History of the Internet|website=Internet Society|language=en-US|access-date=2019-01-22}}</ref> resulted in the [[National Science Foundation Network|NSFNet]] backbone by 1989. The Internet could be defined as the collection of all networks connected and able to interchange [[Internet Protocol]] datagrams with this backbone. Such was the weight of the NSFNET program and its funding ($200 million from 1986 to 1995)—and the quality of the protocols themselves—that by 1990, when the ARPANET itself was finally decommissioned, TCP/IP had supplanted or marginalized most other wide-area computer network protocols worldwide.

When the Internet was opened to the commercial markets, multiple for-profit Internet backbone and access providers emerged. The network routing architecture then became decentralized and this meant a need for exterior routing protocols: in particular, the [[Border Gateway Protocol]] emerged. New Tier 1 ISPs and their peering agreements supplanted the government-sponsored NSFNet, that program being officially terminated on April 30, 1995.<ref name="internetsociety.org"/> The NSFnet-supplied regional networks then sought to buy national-scale Internet connectivity from these now-numerous private long-haul networks.

==Routing through peering==
A bilateral private peering agreement typically involves a direct physical link between two partners. Traffic from one network to the other is then primarily routed through that direct link.

A Tier 1 network may have various such links to other Tier 1 networks.<ref>{{cite book | url=https://books.google.com/books?id=IM-Y2W0RIF0C&dq=tier+1+internet&pg=PA291 | title=Network Routing: Algorithms, Protocols, and Architectures | date=19 July 2010 | publisher=Elsevier | isbn=978-0-08-047497-7 }}</ref><ref>{{cite book | url=https://books.google.com/books?id=fTPmJytNeosC&dq=tier+1+network&pg=PA10 | title=Alcatel-Lucent Scalable IP Networks Self-Study Guide: Preparing for the Network Routing Specialist I (NRS 1) Certification Exam | isbn=978-0-470-52938-6 | last1=Hundley | first1=Kent | date=31 August 2009 | publisher=John Wiley & Sons }}</ref><ref>{{cite book | url=https://books.google.com/books?id=92ZYiSTXkWMC&dq=tier+1+peering&pg=PT113 | title=The Internet Peering Playbook: Connecting to the Core of the Internet | isbn=978-1-937451-02-8 | last1=Norton | first1=William B. | date=8 August 2011 | publisher=DrPeering Press }}</ref>  Peering is founded on the principle of equality of traffic between the partners and as such disagreements may arise between partners in which usually one of the partners unilaterally disconnects the link in order to force the other into a payment scheme. Such disruptive [[Peering#Depeering|de-peering]] has happened several times during the first decade of the 21st century. When this involves large-scale networks involving many millions of customers this may effectively partition a part of the Internet involving those carriers, especially if they decide to disallow routing through alternate routes. This is not largely a technical issue but a commercial matter in which a financial dispute is fought out using the other party's customers as hostages to obtain a better negotiating position. In the worst case, [[multihoming|single-homed]] customers of each network will not be able to reach the other network at all. The de-peering party then hopes that the other network's customers will be hurt more by the decision than its own customers which may eventually conclude the negotiations in its favor.<ref>{{cite web|url=http://www.renesys.com/2008/03/you-cant-get-there-from-here-1/|title=You can't get there from here|work=Renesys |date=2008-03-17|access-date=2014-05-11|quote=Cogent and Telia are having a lover’s quarrel and, as a result, the Internet is partitioned. That means customers of Cogent and Telia cannot necessarily reach one another.}}</ref><ref>{{cite web|url=http://www.internetnews.com/dev-news/article.php/3073411|title='Peering' Into AOL-MSN Outage|date=2003-09-05|access-date=2014-05-11|quote=Some industry watchers believe the problem shows signs of dispute over peering agreements—deals between Internet service providers to create a direct link to route each other's packets rather than pay a third-party network service provider for transport.}}</ref> Lower tier ISPs and other parties not involved in the dispute may be unaffected by such a partition as there exist typically multiple routes onto the same network. The disputes referenced have also typically involved transit-free peering in which one player only exchanged data with the other that involved each other's networks—there was no data transiting ''through'' the other's network destined for other parts of the Internet. By the strict definition of peering and the strict definition of a Tier 1 network, a Tier 1 network only peers with other Tier 1 networks and has no transit routes going anywhere. More practically speaking, Tier 1 networks ''serve'' as transit networks for lower tier networks and only peer with other Tier 1 networks that offer the same services on an adequate scale—effectively being "peers" in the truest sense of the word.<ref>{{cite web|url=http://www.level3.com/en/legal/ip-traffic-exchange-policy/|title=Level 3 IP traffic exchange policy|access-date=2014-05-11|quote=Must provide paid Internet transit services to at least 500 unique transit networks utilizing BGP on a global basis.}}</ref>

More appropriately then, peering means the exchange of an equitable and fair amount of data-miles between two networks, agreements of which do not preclude any pay-for-transit contracts to exist between the very same parties. On the subject of routing, settlement-free peering involves conditions disallowing the abuse of the other's network by sending it traffic not destined for that network (i.e. intended for transit). Transit agreements however would typically cater for just such outbound packets. Tier 1 providers are more central to the Internet backbone and would only purchase transit from other Tier 1 providers, while selling transit to providers of all tiers. Given their huge networks, Tier 1 providers often do not participate in public Internet Exchanges<ref>{{cite book | url=https://books.google.com/books?id=IM-Y2W0RIF0C&dq=tier+1+no+internet+exchange+points&pg=PA293 | isbn=978-0-08-047497-7 | title=Network Routing: Algorithms, Protocols, and Architectures | date=19 July 2010 | publisher=Elsevier }}</ref> but rather sell transit services to such participants and engage in [[private peering]].<ref>{{cite book | url=https://books.google.com/books?id=Rjwr33pdogQC&dq=tier+1+no+internet+exchange+points&pg=PT237 | isbn=978-1-118-39457-1 | title=Global Networks: Engineering, Operations and Design | date=5 November 2012 | publisher=John Wiley & Sons }}</ref> [[Colocation center]]s often host [[private peering]] connections between their customers, internet transit (tier 1) providers and cloud providers.<ref>https://www.servethehome.com/touring-the-phoenixnap-data-center/2/</ref><ref>https://www.datacenterdynamics.com/en/analysis/the-rise-and-rebirth-of-carrier-hotels/</ref>

In the most logical definition, a Tier 1 provider will never pay for transit because the set of all Tier 1 providers sells transit to all of the lower tier providers everywhere, and because{{olist|list-style-type=lower-alpha|all Tier 1 providers peer with every other Tier 1 provider globally and,|the peering agreement allows ''access'' to all of the transit customers, this means that|the Tier 1 network contains all hosts everywhere that are connected to the global Internet.}}As such, by the peering agreement, all the customers of any Tier 1 provider already have access to all the customers of all the other Tier 1 providers without the Tier 1 provider itself having to pay transit costs to the other networks. Effectively, the actual transit costs incurred by provider A on behalf of provider B are logically identical to the transit costs incurred by provider B on behalf of provider A—hence there not being any payment required.

==List of Tier 1 networks==
These networks are universally recognized as Tier 1 networks, because they can reach the entire internet ([[IPv4]] and [[IPv6]]) via settlement-free peering. The CAIDA AS rank is a rank of importance on the internet.<ref name="CAIDA AS ranking" />

{| class="wikitable sortable"
|-
!Name
!Headquarters
![[Autonomous system (Internet)|AS number]]
! data-sort-type="number" |CAIDA AS rank<ref name="CAIDA AS ranking">[https://asrank.caida.org CAIDA AS Rank]</ref>
! data-sort-type="number" |Fiber route (km) 
!Peering policy
|-
|[[AT&T]]<ref>{{cite web|url=https://asrank.caida.org/asns?asn=7018|title=AS Rank: AS7018 (AT&T Services, Inc.)|access-date=2022-08-08}}</ref>
|{{flag|United States|name=United States}}
|7018
|29
|660,000<ref>{{Cite web|url=http://www.att.com/gen/general?pid=7462|title=AT&T Communications Inc}}</ref>
|[http://www.corp.att.com/peering/ AT&T Peering policy]
|-
|[[Deutsche Telekom#Deutsche Telekom Global Carrier|Deutsche Telekom Global Carrier]]<ref>{{cite web|url=https://asrank.caida.org/asns?asn=3320|title=AS Rank: AS3320 (Deutsche Telekom AG)|access-date=2020-10-26}}</ref>
|{{flag|Germany|name=Germany}}
|3320
|17
|250,000<ref>{{cite web|url=https://globalcarrier.telekom.com/business-areas/internet-content|title=Internet and Contents|date=6 January 2025 }}</ref>
|[https://www.peeringdb.com/asn/3320 DTAG Peering Details]
|-
|[[GTT Communications]]
|{{flag|United States|name=United States}}
|3257
|4
|232,934<ref>{{Cite web |url=https://www.gtt.net/wp-content/uploads/2017/02/GTT-Investor-Presentation-February-2017.pdf |title=Investor Presentation |access-date=2017-11-18 |archive-date=2017-12-01 |archive-url=https://web.archive.org/web/20171201042822/https://www.gtt.net/wp-content/uploads/2017/02/GTT-Investor-Presentation-February-2017.pdf |url-status=dead }}</ref><ref name=":0">{{cite web|url=https://www.bloombergquint.com/business/gtt-buys-interoute-for-2-3-billion-to-gain-europe-fiber-network|title=GTT Buys Interoute for $2.3 Billion to Gain Europe Fiber Network|website=BloombergQuint|date=26 February 2018 |access-date=2019-02-05}}</ref>
|[http://www.gtt.net/peering/ GTT Peering Policy]
|-
|[[Liberty Global]]<ref>{{cite web|url=http://bgp.he.net/AS6830#_graph4|title=AS6830 IPv4 route propagation|access-date=2020-10-26}}</ref><ref>{{cite web|url=https://asrank.caida.org/asns?asn=6830|title=CAIDA AS Rank|access-date=2020-10-26}}</ref>
|{{flag|Netherlands|name=Netherlands}}<ref>{{Cite web|url=http://www.libertyglobal.com/about-us-contact-us.aspx|title = Contact}}</ref>
|6830
|26
|800,000<ref>{{cite web|title=Liberty Global {{!}} largest international cable company|url=http://www.libertyglobal.com/index.html|website=www.libertyglobal.com|access-date=15 August 2017|archive-url=https://web.archive.org/web/20170809184226/http://www.libertyglobal.com/index.html|archive-date=2017-08-09|url-status=dead}}</ref>
|[https://www.libertyglobal.com/operations/business-services/global-peering-principles/ Peering Principles]
|-
|[[Lumen Technologies]] (formerly [[CenturyLink]], formerly [[Level 3 Communications|Level 3]])<ref name=":1">{{cite web|url=http://news.centurylink.com/2017-11-01-CenturyLink-completes-acquisition-of-Level-3|title=CenturyLink completes acquisition of Level 3|website=MediaRoom|access-date=2019-01-22}}</ref><ref name=":2">{{cite web|url=https://asrank.caida.org/asns?asn=209|title=CAIDA AS Rank|date=2016-09-01|access-date=2016-09-01}}</ref><ref name=":5">{{cite web|title=CenturyLink Transforms, Rebrands as Lumen®|url=https://ir.lumen.com/news/news-details/2020/CenturyLink-Transforms-Rebrands-as-Lumen/default.aspx|access-date=2020-10-21|website=ir.lumen.com|language=en-US}}</ref>
|{{flag|United States|name=United States}}
|3356
|1
|885,139<ref name=":3">{{cite press release|url=https://www.prnewswire.com/news-releases/centurylink-completes-largest-deployment-of-gfast-technology-in-north-america-300325687.html|title=CenturyLink completes largest deployment of G.fast technology in North America|author=CenturyLink, Inc.|website=www.prnewswire.com|language=en|access-date=2019-01-22}}</ref><ref name=":4">{{Cite web |url=http://www.level3.com/~/media/files/brochures/en_dataserv_br_secureinternetservices.pdf |title=Level 3® Internet Services |access-date=2016-09-06 |archive-date=2016-10-20 |archive-url=https://web.archive.org/web/20161020133804/http://www.level3.com/~/media/files/brochures/en_dataserv_br_secureinternetservices.pdf |url-status=dead }}</ref>
|[https://www.lumen.com/en-us/about/legal/peering-policy.html Lumen Peering Policy]
|-
|[[NTT Communications]] (formerly [[Verio]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=2914|title=CAIDA AS Rank|access-date=2020-10-26}}</ref>
|{{flag|Japan|name=Japan}}
|2914
|5
|{{dunno}}
|[https://www.gin.ntt.net/support-center/policies-procedures/routing/ Global Peering Policy]
|-
|[[Orange Group|Orange]]<ref>{{cite web|url=https://internationalcarriers.orange.com/en/offers/ip-transit.html|title=AS Rank: AS5511 (Orange S.A.)|access-date=2020-10-26}}</ref>
|{{flag|France|name=France}}
|5511
|11
|495,000 <ref>{{cite web|url=https://wholesale.orange.com/international/en/our-networks/orange-global-networks.html|title=450 000 km of submarine cables + 45 000 km terrestrial networks}}</ref>
|[https://www.peeringdb.com/asn/5511 OTI peering policy]
|-
|[[PCCW|PCCW Global]]
|{{flag|Hong Kong|name=Hong Kong}}
|3491
|10
|{{dunno}}
|[https://www.peeringdb.com/asn/3491 Peering policy]
|-
|[[Tata Communications]] (prev. [[VSNL]] prev. [[VSNL International Canada|Teleglobe]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=6453|title=AS Rank: AS6453 (TATA COMMUNICATIONS (AMERICA) INC)|access-date=2020-10-26}}</ref>
|{{flag|India|name=India}}
|6453
|6
|700,000<ref>{{Cite web|url=http://www.tatacommunications.com/glance/our-network|title = Tata Communications &#124; Digital Ecosystem Enabler}}</ref>
|[https://www.peeringdb.com/asn/6453 Peering Policy]
|-
|[[Telecom Italia Sparkle]] (Seabone)<ref>{{cite web|url=https://asrank.caida.org/asns?asn=6762|title=AS Rank: AS6762 (Telecom Italia S.p.A.)|access-date=2020-10-26}}</ref>
|{{flag|Italy|name=Italy}}
|6762
|8
|560,000
|[https://www.peeringdb.com/asn/6762 Peering Policy]
|-
|[[Arelion]] (formerly [[Telia Carrier]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=1299|title=AS Rank: AS1299 (Telia Company AB)|access-date=2020-10-26}}</ref>
|{{flag|Sweden|name=Sweden}}
|1299
|2
|70,000<ref>{{cite web |title=Arelion |url=https://www.arelion.com/about-us.html |access-date=2022-10-31 |website=Arelion}}</ref>
|[https://www.arelion.com/dam/jcr:58bcf8cb-7cd2-4108-a5d9-e65bc2a01bb5/Arelion%20%20Peering%20Policy%20Clean%20(12.22.pdf Arelion's IP Network Peering Policy]
|-
|[[Telxius]] (Subsidiary of {{lang|es|[[Telefónica]]|italic=no}})<ref>{{cite web|url=https://asrank.caida.org/asns?asn=12956|title=AS Rank: AS12956 (Telefonica International Wholesale Services II, S.L.U.)|access-date=2020-10-26}}</ref>
|{{flag|Spain|name=Spain}}
|12956
|15
|65,000<ref>{{Cite web | url=http://telxius.com/wp-content/uploads/2016/12/Fichas_Telxius_Capacity-Services.pdf | title=Capacity Services | publisher=Telxius | access-date=2024-08-11 | website=telxius.com}}</ref>
|[https://telxius.com/wp-content/uploads/2017/08/Peering-policy-Telxius.pdf Peering Policy]
|-
|[[Verizon|Verizon Enterprise Solutions]] (formerly [[UUNET]]){{refn|<ref name="fiercetelecom.com">{{Cite web|url=http://www.fiercetelecom.com/telecom/after-delay-verizon-wraps-1-8b-xo-acquisition-deepens-metro-fiber-density-45-markets|title = After delay, Verizon wraps $1.8B XO acquisition, deepening metro fiber density in 45 markets| date=February 2017 }}</ref><ref name="asrank.caida.org">{{cite web|url=https://asrank.caida.org/asns?asn=701|title=AS Rank: AS701 (MCI Communications Services, Inc. d/b/a Verizon Business) |access-date=2020-10-26}}</ref><ref name="AS Rank: AS702 MCI Communications">{{cite web|url=https://asrank.caida.org/asns?asn=702|title=AS Rank: AS702 (MCI Communications Services, Inc. d/b/a Verizon Business)|access-date=2020-10-26}}</ref><ref name="AS Rank: AS703 MCI Communications">{{cite web|url=https://asrank.caida.org/asns?asn=703|title=AS Rank: AS703 (MCI Communications Services, Inc. d/b/a Verizon Business)|access-date=2020-10-26}}</ref>}}
|{{flag|United States|name=United States}}
|701
|25
|805,000<ref>{{cite web|url=https://www22.verizon.com/wholesale/productguide/voice_services/when-you-need-quality-reliability-and-a-global-presence-trust-verizon-global-wholesale-for-all-of-your-voice-services-requirements.html|title=When you need quality, reliability and a global presence, trust Verizon Partner Solutions for all of your VOICE SERVICES requirements|website=www22.verizon.com|access-date=2019-01-22}}</ref>
|[http://www.verizonenterprise.com/terms/peering/ Verizon UUNET Peering policy 701, 702, 703]
|-
|[[Zayo Group]] (formerly [[AboveNet]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=6461|title=AS Rank: AS6461 (Zayo Bandwidth)|access-date=2020-10-26}}</ref>
|{{flag|United States|name=United States}}
|6461
|9
|196,339<ref>{{cite web|url=https://www.zayo.com/services/dark-fiber/|title=Network Solutions Provider - Dark Fiber Network |publisher=Zayo Group|language=en-US|access-date=2019-01-22}}</ref>
|[https://peeringdb.com/asn/6461 Zayo Peering Policy]
|}

While most of these Tier 1 providers offer global coverage (based on the published network map on their respective public websites), there are some which are restricted geographically. However these do offer global coverage for mobiles and IP-VPN type services which are unrelated to being a Tier 1 provider.

A 2008 report shows Internet traffic relying less on U.S. networks than previously.<ref>{{cite news|url=https://www.nytimes.com/2008/08/30/business/30pipes.html?pagewanted=all|work=New York Times|title=Internet Traffic Begins to Bypass the US|first=John|last=Markoff|date=2008-08-30}}</ref>

==Regional Tier 1 networks==
{{See also|Internet exchange point}}
A common point of contention regarding Tier 1 networks is the concept of a ''regional Tier 1'' network. A regional Tier 1 network is a network which is not transit-free globally, but which maintains many of the classic behaviors and motivations of a Tier 1 network within a specific region.

A typical scenario for this characteristic involves a network that was the incumbent telecommunications company in a specific country or region, usually tied to some level of government-supported monopoly. Within their specific countries or regions of origin, these networks maintain peering policies which mimic those of Tier 1 networks (such as lack of openness to new peering relationships and having existing peering with every other major network in that region). However, this network may then extend to another country, region, or continent outside of its core region of operations, where it may purchase transit or peer openly like a Tier 2 network.

A commonly cited example of these behaviors involves the incumbent carriers within Australia, who will not peer with new networks in Australia under any circumstances, but who will extend their networks to the United States and peer openly with many networks.{{citation needed|date=November 2010}}<!--if it is commonly cited, why not here?--> Less extreme examples of much less restrictive peering requirements being set for regions in which a network peers, but does not sell services or have a significant market share, are relatively common among many networks, not just regional Tier 1 networks.

While the classification ''regional Tier 1'' holds some merit for understanding the peering motivations of such a network within different regions, these networks do not meet the requirements of a true global Tier 1 because they are not transit-free globally.<ref>{{cite web|url=https://drpeering.net/FAQ/Who-are-the-Tier-1-ISPs.php|title=Who are the Tier 1 ISPs?|website=drpeering.net|access-date=2019-05-22}}</ref>

==Other major networks==
This is a list of networks that are often considered and close to the status of Tier 1, because they can reach the majority (50+%) of the internet via settlement-free peering with their global rings. However, routes to one or more Tier 1 are missing or paid. Therefore, they are technically [[Tier 2 network|Tier 2]], though practically something in between.
{| class="wikitable sortable"
|-
! style="width:22%" | Name
! Headquarters
! [[Autonomous system (Internet)|AS Number]]
! CAIDA AS Rank<ref name="CAIDA AS ranking" />
! Reason
|-
|[[China Telecom]]
|{{flag|China|name=China}}
|4134/4809
|87
|Purchases transit from [[Level 3 Communications|Level 3]]/AS3356, [[Cogent Communications|Cogent]]/AS174, [[Verizon Communications|Verizon]]/AS701.
|-
|[[China Unicom]]
|{{flag|China|name=China}}
|4837
|181
|Purchases transit from [[Cogent Communications|Cogent]]/AS174, [[Verizon Communications|Verizon]]/AS701, [[Level 3 Communications|Level3]]/AS3356, [[Orange S.A.]]/AS5511.
|-
|[[Singtel]]<ref>{{cite web|url=https://asrank.caida.org/asns?asn=7473|title=AS Rank: AS7473 (Singapore Telecommunications (SINGTEL Internet Exchange))|access-date=2022-02-10}}</ref>
|{{flag|Singapore|name=Singapore}}
|7473
|16
|Purchases transit from [[Arelion]]/AS1299, [[Zayo Group|Zayo]]/AS6461, [[Tata Communications]]/AS6453.
|-
|[[Cogent Communications]] (formerly [[PSINet]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=174|title=AS Rank: AS174 (Cogent Communications)|access-date=2020-10-26}}</ref>
|{{flag|United States|name=United States}}
|174
|3
|No IPv6 routes to [[Hurricane Electric]]/AS6939
|-
|[[Hurricane Electric]]<ref>{{cite web|url=https://asrank.caida.org/asns?asn=6939|title=AS Rank: AS6939 (Hurricane Electric LLC)|access-date=2020-10-26}}</ref>
|{{flag|United States|name=United States}}
|6939
|5
|IPv4: Purchases transit from [[Telia Carrier|Arelion]]/AS1299 to reach [[GTT Communications|GTT]]/AS3257, [[NTT Communications Corp|NTT]]/AS2914 and [[Cogent Communications|Cogent]]/AS174.<br />IPv6: Lack of peering with [[Cogent Communications|Cogent]]/AS174.<ref>{{cite web|url=http://www.datacenterknowledge.com/archives/2009/10/22/peering-disputes-migrate-to-ipv6/|title=Peering Disputes Migrate to IPv6|date=22 October 2009}}</ref><ref>{{cite web|url=https://mailman.nanog.org/pipermail/nanog/2009-October/014017.html|title=IPv6 internet broken, cogent/hurricane not peering|date=12 October 2009 }}</ref>
|-
|[[RETN (Network Services Provider)|RETN]]<ref>{{cite web|url=https://asrank.caida.org/asns?asn=9002|title=AS Rank: AS9002 (RETN Limited)|access-date=2020-10-26}}</ref>
|{{flag|United Kingdom|name=United Kingdom}}
|9002
|12
|Purchases transit from [[Level 3 Communications|Level 3]]/AS3356
|-
|[[Vodafone|Vodafone Carrier Services]]<br />(formerly [[Cable & Wireless Worldwide|Cable & Wireless]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=1273|title=AS Rank: AS1273 (Vodafone Group PLC)|access-date=2020-10-26}}</ref>
|{{flag|United Kingdom|name=United Kingdom}}
| 1273
| 13
| Purchases transit from [[Telia Carrier|Arelion]]/AS1299 to reach [[AT&T]]/AS7018.<ref>{{cite web|url=https://bgp.he.net/AS1273#_graph4|title=AS1273 Cable and Wireless Worldwide plc - bgp.he.net|website=bgp.he.net|access-date=2019-11-03}}</ref>
|-
|[[Verizon Communications|Verizon Enterprise Solutions]]<br />(formerly [[XO Communications]])<ref>{{cite web|url=https://asrank.caida.org/asns?asn=2828|title=AS Rank: AS2828 (MCI Communications Services, Inc. d/b/a Verizon Business)|access-date=2020-10-26}}</ref>{{refn|<ref name="fiercetelecom.com">{{Cite web|url=http://www.fiercetelecom.com/telecom/after-delay-verizon-wraps-1-8b-xo-acquisition-deepens-metro-fiber-density-45-markets|title = After delay, Verizon wraps $1.8B XO acquisition, deepening metro fiber density in 45 markets| date=February 2017 }}</ref><ref name="asrank.caida.org">{{cite web|url=https://asrank.caida.org/asns?asn=701|title=AS Rank: AS701 (MCI Communications Services, Inc. d/b/a Verizon Business) |access-date=2020-10-26}}</ref><ref name="AS Rank: AS702 MCI Communications">{{cite web|url=https://asrank.caida.org/asns?asn=702|title=AS Rank: AS702 (MCI Communications Services, Inc. d/b/a Verizon Business)|access-date=2020-10-26}}</ref><ref name="AS Rank: AS703 MCI Communications">{{cite web|url=https://asrank.caida.org/asns?asn=703|title=AS Rank: AS703 (MCI Communications Services, Inc. d/b/a Verizon Business)|access-date=2020-10-26}}</ref>}}
|{{flag|United States|name=United States}}
|2828
|220
|IPv6: Purchases transit from [[Cogent Communications]]/AS1239 to reach [[Vodafone|Vodafone (CW)]]/AS1273 and [[Telecom Italia|Telecom Italia Sparkle (Seabone)]]/AS6763.
|-	
|[[Telstra]]<ref>{{Cite web|title=Internet Service Provider 3-Tier Model {{!}} ThousandEyes|url=https://www.thousandeyes.com/learning/techtorials/isp-tiers|access-date=2021-07-12|website=www.thousandeyes.com|language=en}}</ref>
|{{flag|Australia|name=Australia}}
|4637
|14
|Purchases transit from [[Level 3 Communications|Level 3]]/AS3356, [[Telia Carrier|Arelion]]/AS1299, [[Zayo]]/AS6461.
|-
|[[Comcast]]<ref>{{cite web|url=https://asrank.caida.org/asns?asn=7922|title=AS Rank: AS7922 (Comcast Cable Communications, LLC)|access-date=2020-10-26}}</ref>
|{{flag|United States|name=United States}}
|7922
|29
|Purchases transit from [[Tata Communications|Tata]]/AS6453
|}

==See also==
* [[Optical Carrier transmission rates]]
* [[Interconnect agreement]]
* [[Internet exchange point]]
* [[List of Internet exchange points]]

==References==
{{Reflist|30em}}

{{telecommunications}}

{{DEFAULTSORT:Tier 1 Network}}
[[Category:Internet architecture]]
[[Category:Tier 1 networks| ]]