ISPs, Backbones and Peering 14-740: Fundamentals of Computer - - PowerPoint PPT Presentation

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ISPs, Backbones and Peering 14-740: Fundamentals of Computer - - PowerPoint PPT Presentation

Nov 27, 2022 261 likes •653 views

ISPs, Backbones and Peering 14-740: Fundamentals of Computer Networks Bill Nace Material from Computer Networking: A Top Down Approach, 6 th edition. J.F. Kurose and K.W. Ross Administrivia Norton2010 Paper Review for today Lab0 is

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Material from Computer Networking: A Top Down Approach, 6th edition. J.F. Kurose and K.W. Ross

ISPs, Backbones and Peering

14-740: Fundamentals of Computer Networks Bill Nace

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Administrivia

  • Norton2010 Paper Review for today
  • Lab0 is posted

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Last Lecture

  • Internet TCP/IP architecture
  • Layering not strictly enforced
  • “Hourglass” -- IP ueber alles
  • Allows rapid innovation at layers below
  • Flexible applications / services above
  • IETF process
  • “Rough consensus and running code”
  • End-to-end argument
  • Does it still apply?

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Another take on Layered Architecture

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traceroute

  • ISPs and Backbones
  • Peering and Settlements
  • Peering Evolution
  • Interconnections

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A Packet’s Journey

  • Packets travel across many networks
  • Particular protocols will be studied later
  • This lecture motivates why routing

mechanics are necessary

CMU Pgh PennRen Some NW Tier 1 ISP Tier 1 ISP Tier 1 ISP Some ISP Little ISP Cheap ISP Huge ISP CMU Kobe A B C E F D G H J

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CMU’s Infrastructure

  • Two 10 Gigabit Ethernet links

(singlemode fiber) to Pittsburgh Supercomputer Center

  • From Cisco 6500s located in Cyert

and Stever House

  • “Redundancy” links to PennRen /

Level3 over 1Gbps rate-limited 10 Gigabit Ethernet

  • Money
  • $40K per year to PennRen
  • A PA state education network
  • $100K to PSC, $100K to Level3
  • $300K per year on fiber leases

1Gbps/10Gbps 10Gbps 10Gbps 1Gbps Internal External CMU Internal PennRen PSC Internet2 Level3 Comodity Internet

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Backbones

  • In the beginning ... of Internet time
  • Single backbone: NSFNet
  • Everyone on the “Internet” was on NSFNet
  • A backbone network enables all connected

end-hosts (users and companies) to communicate with each other

  • No interconnection problems

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Backbones (2)

  • Commercial backbone providers emerged
  • Technology transfer!
  • A “Good Thing”
  • If US Government was managing the

Internet, might not be so successful

  • We all expect universal Internet

connectivity

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Interfaces: Transit

  • Transit / provider-customer
  • ISP sells access to another ISP or

company

  • e.g. CMU buys transit (or access to

Internet) from Level3

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Interfaces: Peering

  • Reciprocal access to each other’s customers
  • Usually free exchange of traffic
  • DO NOT serve as transit for 3rd party data
  • E.g. Google and MSN peer with each other, so email

messages between Gmail and Hotmail are transferred directly, without going through their transit providers

  • These relationships are confidential business secrets
  • Roughly hierarchical, though the topology is flattening

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Tier 1 ISP

  • Internet backbone providers
  • Peers with every other Tier-1 in “Internet Region”
  • Who is a major ISP in your country?
  • US?
  • India?
  • China?
  • Careful: “Tier-1” is an overloaded and misleading term

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Images courtesy of Level-3

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Images courtesy of Verizon

>4200 networks in 142 nations, many at OC-768 speeds

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Image courtesy of tatacommunications.com/network

Tata: "Discover the World's Largest Global Footprint"

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“Typical” Infrastructure

  • High speed links
  • Level3 operates 40Gbps DWDM networks
  • High performance routers
  • Over-provisioned bandwidth
  • 40 ms delay within region
  • <1% packet loss
  • Global presence (or at least multi-continent)

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“Typical” Tier-1 Relationships

  • Directly connected to other Tier-1 ISPs (i.e.

peer with)

  • Connected to a large number of Tier-2 ISPs
  • Vertically integrated: sell services directly to

customers

  • International in coverage
  • Ecosystem: do not buy transit from another

provider in order to reach the whole Internet

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Why do Tier-1 ISPs need to peer with each other?

  • No single Tier-1 ISP can reach the whole

Internet on its own

  • Internet is a network of networks
  • But Tier-1 ISPs have a restrictive peering policy
  • Do not peer with other non-Tier-1 ISPs
  • They are potential revenue generating

customers

  • No incentive to accept additional peers

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What is a Tier-2 ISP?

  • Network infrastructure is usually regional
  • Customer of Tier-1 ISP(s) – needs to buy transit
  • Provider of customers – also re-sells this transit
  • Peers with other Tier-2 ISPs – settlement free

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Tier 1 ISP Tier 1 ISP Tier 1 ISP IXP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP

Tier-2 ISP pays Tier-1 for connectivity to rest

  • f internet

Multi-connection relationships possible Tier-2 ISPs also peer

  • privately. Interconnection

can be direct or via IXP

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Thinking time

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  • Why do Tier-2 ISPs need to buy transit

from a Tier-1 provider?

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Thinking time

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  • Why do Tier-2 ISPs peer with each other?
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Open Peering Policy

  • Tier-2 ISPs have an open peering policy
  • Peer with anyone possible
  • Costs of peering have to be balanced against

gains for a Tier-2 ISP

  • Management cost: usually settlement-free

peering means both parties should send approx equal amounts of traffic to each other

  • Maintenance cost: extra equipment,

transmission capacity to meeting point, exchange and other fees

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Content Providers

  • Do not sell transit
  • Category A: Focus on content creation
  • Do not want to operate a network
  • Do not have expertise in maintaining peering

relationships — router, policy, negotiations, …

  • No Peering Policy
  • Category B: Sophisticated, large-scale players
  • Use peering to improve user experience
  • Open Peering Policy

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Peering Ecosystem

Tier 1 ISPs Tier 2 ISPs Content / Enterprise Companies

Full Mesh Peering Partial Mesh Peering Generally No Peering Must Buy Transit Transit Free Must Buy Transit

Internet Region

Things are never so clear-cut . . .

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traceroute

  • ISPs and Backbones
  • Peering and Settlements
  • Peering Evolution
  • Interconnections

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US Evolution

  • 1999/2000 economic collapse
  • Telecom sector
  • Need to rethink their business model
  • Need to cut costs
  • General dotcom bust
  • Lots of cheap equipment on eBay
  • Transit rates drop
  • Upstream provider @Home for cable companies went

bankrupt

  • Peer-to-peer file sharing grows exponentially in popularity

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Transit Prices are Falling

  • Price per Mbs ➙ 63% per year decline
  • Luckily, volume is increasing even more
  • Somewhat bad for Tier-1 ISPs

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Content Companies are Peering

  • Network savvy, large scale enterprises
  • MSN, Yahoo, Google, Ebay, Walmart, …
  • Yahoo has an open peering policy
  • Reduce transit costs
  • Improve end-user experience
  • Good for content companies
  • Bad for Tier-1 ISPs

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traceroute

  • ISPs and Backbones
  • Peering and Settlements
  • Peering Evolution
  • Interconnections

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Interconnection

  • How do two networks interconnect with

each other?

  • We are talking about routers in two

different companies, under separate administrative control

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Public Peering

  • U.S. government decided to let commercial companies

take over management of the backbone networks

  • 1991: Commercial Internet Exchange (CIX)
  • 1 router in Santa Clara, CA
  • 1995: Network Access Points (NAPs) in SF

, Chicago, NY, D.C.

  • More recent: Internet Exchange Point (IXP)
  • 30 in US, 6 in Japan
  • “More is good” because of congestion, at one point

20% of traffic going through the 1st NAP was dropped!

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ISP Connections

Tier 1 ISP Tier 1 ISP Tier 1 ISP IXP (Meet-me room) Tier 1 ISP

Tier-1 providers interconnect privately (Peer) Tier-1 providers also interconnect at Internet Exchange Points (IXP) (30 in US)

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Private Peering

  • Two networks bypass IXPs and directly peer
  • In response to congestion at some IXPs
  • Business reasons
  • Also more cost-effective
  • There are limited number of IXPs at major regions
  • Can privately peer in other locations
  • Sometimes take a hybrid approach
  • Public exchange for some peers
  • Private meeting point for others

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Provider-customer Interconnection

  • Point-of-presence (PoP)
  • Customer typically leases a high-speed

link from a 3rd party telecomm provider

  • Directly connects a router at a provider’s

PoP

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Various Methods

  • How do two networks interconnect with

each other?

  • Many methods: Public Peering, Private

Peering, Provider-customer PoP

  • There are really no industry-specific

regulations, mostly purely driven by commercial and economic forces

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How does the world connect to Facebook? Facebook’s network IXP in Germany IXP in Japan IXP in Sweden Level3 Amazon Directly Connected Peer?

Image courtesy of Teun Vink (teun.tv)

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Lesson Objectives

  • Now, you should be able to:
  • analyze business practices of various enterprises

using the multi-tier network model (Tier-1, 2, etc) and common peering practices

  • describe the relationships and associated

motivations for enterprises on the internet

  • analyze the effect of recent trends in internet usage

patterns on the various business enterprises on the internet

  • describe interconnection methods between

enterprise networks

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