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VPNs

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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VPNs

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  1. 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

  2. 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

  3. VPNs • Problems with the Internet • Congestion: slows transmissions • Reliability: cannot always connect, sometimes fails during transmissions • Lack of security

  4. 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

  5. VPNs • IPsec Transport Mode • End-to-end security for hosts Local Network Internet Local Network Secure Communication

  6. VPNs • IPsec Tunnel Mode • IPsec server at each site • Secure communication between sites Local Network Internet Local Network IPsec Server Secure Communication

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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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