Wide Area Network Overview

Wide Area Networks

Where We’ve Been • Basic Concepts • Chapters 1-4 • Local Area Networks • Layers 1 and 2 • Switched Ethernet networks (Chapter 5) • Local wireless networks (Chapters 6 and 7) • TCP/IP • Layers 3 and 4 (Chapters 8 and 9) • Wide Area Networks • Layers 1-4 (Chapter 10) © 2013 Pearson

10.1: LANs, MANs, and WANs • Local Area Networks (LANs) • On the customer premises • Wide Area Networks (WANs) • Connect sites across a region, country, the world • Metropolitan Area Networks (MANs) • Connect sites in a single metropolitan area (a city and its suburbs) • A type of WAN © 2013 Pearson

10.8: Leased Line Speeds • Below 50 Mbps • North American Digital Hierarchical • CEPT Hierarchy in Europe • Different in other parts of the world • Wire at low speeds, fiber at higher speeds • Above 50 Mbps • SONET/SDH • Optical fiber only • Harmonized worldwide © 2013 Pearson

Cable Modem Service • Coaxial cable service was created to bring television to homes that had poor over-the- air reception • Now also offers two-way data service called cable modem service • Popular in the United States • Not popular in most countries © 2013 Pearson

ADSL versus Cable Modem Service • In general … • Cable modem service offers somewhat faster individual throughput at a somewhat higher cost. • ADSL service offers somewhat slower individual throughput at a somewhat lower cost. © 2013 Pearson

10.15: Switched Data Network Standards • Frame Relay • Started to grow in the 1990s • Inexpensive and fast compared to X.25 • 256 kbps to about 40 Mbps • This is the range of greatest corporate demand for WAN speeds © 2013 Pearson

10.15: Switched Data Network Standards • Frame Relay • Grew rapidly in the 1990s thanks to low prices • Took market share away from leased line corporate networks • Carriers have raised their prices to improve profit margins • This has reduced growth • Many companies are going back to leased lines for many links © 2013 Pearson

10.15: Switched Data Network Standards • ATM • Much higher speeds than Frame Relay, at much higher prices • Speeds of 1 Mbps to gigabits per second • Adoption for PSDN service has been limited • Created to replace the core of the Public Switched Telephone Network • Widely adopted for the Public Switched Telephone Network core © 2013 Pearson

10.15: Switched Data Network Standards • Metropolitan Area Ethernet • Metropolitan area network (MAN): city & environs • Smaller distances than national or international WANs, so lower prices and higher speeds • Speeds of 1 Mbps to 100 Mbps • Little learning is needed because all firms are familiar with Ethernet • Carrier can provision or re-provision service speed rapidly, giving flexibility • The only PSDN service growing rapidly © 2013 Pearson

10.17: Using the Internet for Wide Area Networking • The Internet is a Wide Area Network • Many corporations are beginning to use the Internet for some part of their WAN traffic. • In the future, the Internet is likely to carry most corporate site-to-site traffic and other WAN traffic. © 2013 Pearson

10.17: Using the Internet for Wide Area Networking • Attractions • The price per bit transmitted is very low because of large economies of scale. • All corporate sites, employees, customers, suppliers, and other business partners are connected to the Internet. • Issues • The security of traffic flowing over the Internet • Variable quality of service, with no guarantees © 2013 Pearson

Securing the Internet • Border firewall at each site • Virtual private networks • IPsec encryption for sensitive information • SSL/TLS for less sensitive information • Antivirus filtering © 2013 Pearson

Wide Area Network Overview