Editing Tier 1 network (section)

{{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.