NWEN 402 – Peering & Exchange

T2 2015

With material from Geoff Huston, Andy Linton & Valerie Schaeffer

Outline• Connecting the big players of the Internet• What we want it to look like and what it actually

looks like• The problem• The solution

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InterconnectionInterconnection• An overview of how ISPs interact to form

today’s Internet

The Sum of Many Parts• The Internet is the sum of more than 30,000

component service providers (ISPs)

• Each ISP has its own network with services, tariffs, customers, policies.

The Well-Ordered Internet• This view is based on a conventional

distribution infrastructure

• Every relationship is bilateral– a provider sells services to a consumer

• Tiering of the ISP sector– Tier 1 - global backbone transit networks– Tier 2 - national wholesale transit networks– Tier 3 - local retail access ISPs

The Well-Ordered Internet

Client

Provider

Local ISP

Regional ISP

National ISP

Transit ISP

Local ISP Local ISP Local ISP Local ISP Local ISP

Transit ISP Transit ISP

National ISP National ISP National ISP

Regional ISP Regional ISP Regional ISP Regional ISP

• The resultant structure is a hierarchy of relationships

The Internet - as we know it• The competitive ISP industry tends to equilibrate on the lowest local

cost structures• There are no objective criteria to identify who is the provider and who is

the customer• Debt is better than profit as a means of leverage of ISP value

– there are fewer ways of establishing true value

• underlying carriage tariffs shape Internet-based ‘locality’• Within each local tier cell ISPs tend to SKA peer - or not

– bluff is a critical component of the peering game

• Strict tiering blurs because of the confusion over value identification

– is content of equal value to transit?

The Internet - as we know it

Exchange

Exchange

ExchangeExchange

ISP

ISP

ISP

ISP

ISP

ISP

ISPClient Net Client Net

Client Net

Client Net

Client Net

Client Net

Client NetClient Net

Client Net

Client Net

Client Net

Client Net

Client Net

Client Net

Client Net Client Net

The Problem - as we see it• how to interconnect many thousands of

component networks while:• minimizing local cost everywhere by:

– localizing transit traffic– matching diverse import, export and transit policies– avoiding super dense traffic black holes– maintaining stability and quality– both technical and financial

• and also adding thousands more component networks

The Role of the Exchange• An examination of the rationale for public

Internet exchanges.

• https://www.youtube.com/watch?v=cpAUedhcjAY&feature=plcp

The N-squared problem– N2 circuits, N2 peerings– questionable scaling properties

The Exchange Router• Too simple• Router-based exchanges impose transit policy

A

Exchange Router selects preferredpath to destination A

The Exchange Switch

Exchange LAN Switch

A

Route PeerMesh

Bilateral peering allowseach ISP to select preferredpath to destination A

The Exchange L2 Switch– An L2 switch does not implement routing policy– Routing policy is then the outcome of bilateral

agreements

The Distributed Exchange

Switching Mesh

PeeringVirtual Circuits

• Use of L2 virtual circuits to support bilateral peering eliminates the need for co-location

Adding Value to the Exchange

• exchanges represent a very efficient centralized service launch point

UsenetServer

DNSServer

Web Hosting Services

Multicast Router

Route Server

Service Environment

Web CacheServer

Economics of an exchange• Nicholas Economides “The economics of the Internet Backbone”, Law

& Economics Research Paper Series, June 2005.

• Cremer Jacques, Patrick Rey & Jean Tirole “Connectivity in the Commercial Internet” Journal of Industrial Economics, 2000.

• https://www.youtube.com/watch?v=tR1sLLOYxnY

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Bring the rain• Software Defined Exchange

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Gupta, Arpit, Laurent Vanbever et al.. "SDX: A software defined internet exchange." In Proceedings of the 2014 ACM conference on SIGCOMM, pp. 551-562. ACM, 2014.

Economides, Nicholas. "The economics of the Internet backbone." NYU, Law and Economics Research Paper 04-033 (2005): 04-23.

D’Ignazio, Alessio, and Emanuele Giovannetti. "Predicting internet commercial connectivity wars: The impact of trust and operators’ asymmetry." International Journal of Forecasting (2015).

Motivation for rethinking IXP• List three points.

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