Editing Peering (section)

== Modern peering ==

=== Donut peering model ===

The "donut peering" model<ref name="PCH2003lecture">
{{cite web
 |url=http://www.pch.net/resources/papers/topology-and-economics/Topology-and-Economics.ppt
 |title=Internet Topology and Economics: How Supply and Demand Influence the Changing Shape of the Global Network
 |first=Bill
 |last=Woodcock
 |date=13 January 2003
 |work=lecture at the University of Minnesota Digital Technology Center
 |publisher=[[Packet Clearing House]]
 |format=ppt
 |access-date=2011-04-28
}}</ref> describes the intensive interconnection of small and medium-sized regional networks that make up much of the Internet.<ref name="PCH2011survey" /> Traffic between these regional networks can be modeled as a [[toroid]], with a core "[[donut hole]]" that is poorly interconnected to the networks around it.<ref name="Cook2002XI">
{{cite journal
 |url         = http://www.cookreport.com/backissues/nov-dec2002cookrep.pdf
 |title       = Changing Role of Peering & Transit in IP Network Interconnection Economics
 |date        = November–December 2002
 |journal        = Cook Report on Internet
 |volume      = XI
 |issue       = 8–9
 |publisher   = Cook Network Consultants
 |issn        = 1071-6327
 |access-date  = 28 April 2011
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20110719171059/http://www.cookreport.com/backissues/nov-dec2002cookrep.pdf
 |archive-date = 19 July 2011
 |df          = dmy-all
}}</ref>

As [[#Depeering|detailed above]], some carriers attempted to form a cartel of self-described [[Tier 1 network]]s, nominally refusing to peer with any networks outside the [[oligopoly]].<ref name="PCH2011survey" /> Seeking to reduce transit costs, connections between regional networks bypass those "core" networks. Data takes a more direct path, reducing [[Network latency|latency]] and [[packet loss]]. This also improves resiliency between [[Eyeball network|consumers]] and [[Content delivery network|content providers]] via multiple connections in many locations around the world, in particular during [[#Depeering|business disputes]] between the core transit providers.<ref>
{{cite web
 |url         = http://www.mzima.net/pdf/donut_peering.pdf
 |title       = The 'Donut Peering' Model: Optimizing IP Transit for Online Video
 |first       = Grant
 |last        = Kirkwood
 |date        = September 2009
 |access-date  = 2 October 2009
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20091116164326/http://www.mzima.net/pdf/donut_peering.pdf
 |archive-date = 16 November 2009
 |df          = dmy-all
}}</ref><ref name="IPC2009">
{{cite web
 |url=http://ipcommunications.tmcnet.com/topics/ip-communications/articles/63792-deep-dive-into-ip-voice-peering.htm
 |title=A Deep Dive Into IP Voice Peering
 |date=4 September 2009
 |first=Doug
 |last=Mohney
 |publisher=[[Technology Marketing Corporation]]
 |work=IP Communications
 |access-date=2009-09-04
}}</ref>

=== Multilateral peering ===
The majority of BGP AS-AS adjacencies are the product of multilateral peering agreements, or MLPAs.<ref name="PCH2011survey" /> In multilateral peering, an unlimited number of parties agree to exchange traffic on common terms, using a single agreement to which they each accede. The multilateral peering is typically technically instantiated in a [[route server]] or route reflector (which differ from [[Looking Glass server|looking glasses]] in that they serve routes back out to participants, rather than just listening to inbound routes) to redistribute routes via a BGP hub-and-spoke topology, rather than a partial-mesh topology. The two primary criticisms of multilateral peering are that it breaks the shared fate of the forwarding and routing planes, since the layer-2 connection between two participants could hypothetically fail while their layer-2 connections with the route server remained up, and that they force all participants to treat each other with the same, undifferentiated, routing policy. The primary benefit of multilateral peering is that it minimizes configuration for each peer, while maximizing the efficiency with which new peers can begin contributing routes to the exchange. While optional multilateral peering agreements and route servers are now widely acknowledged to be a good practice, mandatory multilateral peering agreements (MMLPAs) have long been agreed to not be a good practice.<ref name="PCHwikiMMLPA">{{cite web
 |url=https://wiki.pch.net/pch:public:ixp-policy-document#layer_3_participant_technical_requirements
 |title=Internet Exchange Point Policy Documents: Layer 3 participant technical requirements: Mandatory multi-lateral peering
 |publisher=[[Packet Clearing House]]
 |access-date=2013-10-04
 |archive-url=https://web.archive.org/web/20140809191753/https://wiki.pch.net/pch:public:ixp-policy-document#layer_3_participant_technical_requirements
 |archive-date=9 August 2014
 |url-status=dead
 }}</ref>

=== Peering locations ===
The modern Internet operates with significantly more peering locations than at any time in the past, resulting in improved performance and better routing for the majority of the traffic on the Internet.<ref name="PCH2011survey" /> However, in the interests of reducing costs and improving efficiency, most networks have attempted to standardize on relatively few locations within these individual regions where they will be able to quickly and efficiently interconnect with their peering partners.

===Exchange points===
As of 2021, the largest exchange points in the world are [[IX.br|Ponto de Troca de Tráfego Metro São Paulo]], in [[São Paulo]], with 2,289 peering networks; OpenIXP in [[Jakarta]], with 1,097 peering networks; and [[DE-CIX]] in [[Frankfurt]], with 1,050 peering networks.<ref>{{cite web |url=https://www.pch.net/ixp/dir#!mt-filters=%7B%22stat%22%3A%5B%22dropdown%22%2C%22%22%2C%22Active%22%5D%7D!mt-sort=prts%2Cdesc!mt-pivot=prts |title=Packet Clearing House - Internet Exchange Point Directory |author=<!--Not stated--> |date=2021-05-28 |website=pch.net |publisher=[[Packet Clearing House]] |access-date=2021-05-28}}</ref> The United States, with a historically larger focus on private peering and commercial public peering, has much less traffic visible on public peering switch-fabrics compared to other regions that are dominated by non-profit membership exchange points. Collectively, the many exchange points operated by [[Equinix]] are generally considered to be the largest, though traffic figures are not generally published. Other important but smaller exchange points include [[AMS-IX]] in Amsterdam, [[LINX]] and [[LONAP]] in [[London]], and [[NYIIX]] in [[New York City|New York]].

URLs to some public traffic statistics of exchange points include:
{{Col-begin}}
{{Col-break}}
* AMS-IX
* DE-CIX
{{Col-break}}
* LINX
* MSK-IX
{{Col-break}}
* TORIX
* NYIIX
{{Col-break}}
* LAIIX
* TOP-IX
{{Col-break}}
* Netnod
* Mix Milano
{{Col-break}}
* ix.br SP
* SFMIX
{{col-end}}