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WAN Technologies. Lecture 9 Paul Flynn. Objectives. WAN Technologies Overview WAN Technologies WAN Design. WAN Technology. WAN Service Providers. Physical Layer: WANs. WAN Line Types and Bandwidth. WAN Devices. CSU/DSU. Modem Transmission. WAN Standards. Circuit Switching.
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WAN Technologies Lecture 9 Paul Flynn
Objectives • WAN Technologies Overview • WAN Technologies • WAN Design
Leased Line • Leased lines are not only used to provide direct point-to-point connections between Enterprise LANS, they can also be used to connect individual branches to a packet switched network.
WAN with X.25 • X.25 provides a low bit rate, shared-variable capacity that may either be switched or permanent
Frame Relay • Most Frame Relay connections are based on PVCs rather than SVCs. It implements no error or flow control. Frame Relay provides permanent shared medium bandwidth connectivity that carries both voice and data traffic.
ATM • Asynchronous Transfer Mode (ATM) is a technology capable of transferring voice, video, and data through private and public networks. It is built on a cell based architecture rather than on a frame-based architecture.
Defining DSL: Digital Subscriber Loop Customer DSL Value-Added Packet Network Copper Loop DSL “Modem” DSL “Modem” • Like dial, cable, wireless, and T1, DSL is a Transmission Technology,NOT a full end-to-end solution • Users don’t “buy” DSL, they “buy” services, such as high-speed Internet, leased line, VPN, and Video on Demand
DSL Modem Technology DSL Service Max. Data Rate Down/Uplink (bps) Line Coding Technology Analog Voice Support Max. Reach (km-feet) VDSL–Very High Bit Rate DSL 25M/1.6M or 8M/8M ??? Yes .9–3,000 Residential SOHO Business ADSL–Asymmetric DSL 8M/1M CAP & DMT 5.5–18,000 Yes IDSL–ISDN DSL 144K/144K 2B1Q No 5.5–18,000 SDSL–Symmetric DSL 768K/768K 2B1Q / CAP No 6.9–22,000 HDSL2– High Bit Rate DSL 1.5M–2.0M/1.5M–2.0M Optis No 4.6–15,000 • Trade-off is Reach vs. Bandwidth • Reach numbers imply “Clean Copper” • Different layer 1 transmission technologies, need a common upper protocol layer to tie them together
Cable Modem • Enhanced Cable Modems enable two-way. High speed data transmissions using the same coaxial lines that transmit cable television.