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VPNs Virtual Private Networks Use the Internet for transmission instead of a PSDN Sometimes called VPNs if use Frame Relay or ATM with added security Internet VPNs Why use the Internet? Inexpensive Business partners are already connected to the same network (the Internet)

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PowerPoint Slideshow about 'VPNs' - ostinmannual


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VPNs

  • Virtual Private Networks

    • Use the Internet for transmission instead of a PSDN

    • Sometimes called VPNs if use Frame Relay or ATM with added security

Internet


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VPNs

  • Why use the Internet?

    • Inexpensive

    • Business partners are already connected to the same network (the Internet)

      • May use different PSDNs, but everybody is connected to the Internet


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VPNs

  • Problems with the Internet

    • Congestion: slows transmissions

    • Reliability: cannot always connect, sometimes fails during transmissions

    • Lack of security


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VPNs

  • IETF developing IPsec security standards

    • IP security

    • At the internet layer

    • Protects all messages at the transport and application layers

E-Mail, WWW, Database, etc.

TCP

UDP

IPsec


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VPNs

  • IPsec Transport Mode

    • End-to-end security for hosts

Local

Network

Internet

Local

Network

Secure Communication


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VPNs

  • IPsec Tunnel Mode

    • IPsec server at each site

    • Secure communication between sites

Local

Network

Internet

Local

Network

IPsec

Server

Secure Communication


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VPNs

  • IPsec Modes Can be Combined

    • End-to-end transport mode connection

    • Within site-to-site tunnel connection

Local

Network

Internet

Local

Network

Tunnel Mode

Transport Mode


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VPNs

  • Another Security System for VPNs is the Point-to-Point Tunneling Protocol (PPTP)

    • For dial-up connections, based on PPP

    • Connects user with securely to a remote access server at a site

Dial-Up

Connection

Local

Network

Internet

PPTP Connection

Remote Access Server


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Virtual Private Networks

  • Other Problems Remain

  • Internet Congestion is Still a Problem

    • Internet throughput tends to be low

  • Internet Reliability is Low

    • Cannot get connections

    • Backbone fails occasionally


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Virtual Private Networks

  • Alternative

    • Avoid the congested and unreliable backbone!

    • Use one ISP that serves all sites

    • Should offer QoS service level agreement (SLAs) for latency and reliability

Site 1

ISP

Site 2


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Virtual Private Networks

  • Alternative

    • Avoid the congested backbone

    • Use ISPs that “peer” with one another: connect with one another not through the Internet backbone

    • May offer end-to-end SLAs

Site 1

ISP A

ISP B

Site 2

Peering


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WANs in Perspective

  • Both Leased Line Networks and PSDNs are widely used and will be for several years to come

  • Leased Line Networking is shrinking while PSDN networking is growing rapidly

  • VPN technology and standards are still immature and use will be very low for several years to come


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