Chapter 15: LAN Systems Business Data Communications, 4e.
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Chapter 15: LAN Systems Business Data Communications, 4e
2 High-Speed LANs 8Why? 8Extraordinary growth in speed, power, and storage capacity of PCs 8Increasing use of LANs as computing platforms 8Examples 8Server farms 8Workgroups with “power” requirements 8High-speed backbones
Business Data Communications, 4e 3 Traditional Ethernet 8Ethernet and CSMA/CD (IEEE 802.3) 8Carrier sense multiple access with collision detection 8Four step procedure 8If medium is idle, transmit 8If medium is busy, listen until idle and then transmit 8If collision is detected, cease transmitting 8After a collision, wait a random amount of time before retransmitting
Business Data Communications, 4e 4 802.3 Medium Notation 8Notation format: 8e.g 10Base5 provides 10Mbps baseband, up to 500 meters 8T and F are used in place of segment length for twisted pair and fiber
Business Data Communications, 4e 5 802.3 10BaseX Media Options
Business Data Communications, 4e 6 Fast Ethernet (100Mbps) 8Easy to integrate with existing systems 8Can use UTP (-TX) or fiber (-FX) 8Uses star-wired topology, using a central multiport repeater (broadcast method) 8If NICs support full-duplex mode, switched hub must be used
Business Data Communications, 4e 7 802.3 100Base-T Options
Business Data Communications, 4e 8 802.3 100BaseX Media Options
Business Data Communications, 4e 9 Gigabit Ethernet 8Still under development 8Retains CSMA/CD protocol and Ethernet format, ensuring smooth upgrade path 8Uses optical fiber over short distances 81-gbps switching hub provides backbone connectivity
Business Data Communications, 4e 10 Gigabit Ethernet Media Options
Business Data Communications, 4e 11 Example 100-Mbps Ethernet Backbone Strategy
Business Data Communications, 4e 12 Token Ring LANs (802.5): Medium Access Control 8Token “seized” by changing a bit on the circulating frame to indicate start of frame rather than token 8Default configuration requires sender to complete transmission and begin receiving transmitted frame before releasing the token 8“Early token release” allows release of token after transmission but before receipt of frame
Business Data Communications, 4e 13 802.5 Transmission Media 8Original specified shielded twisted pair with data rates of 4 and 16mbps 8New addition to standard allows use of UTP for 4mbps 8Utilizes differential Manchester encoding 81997 update to IEEE 802.5 introduced dedicated token ring (DTR).
Business Data Communications, 4e 14 Fibre Channel 8combine the best features of channel and protocol- based technologies 8the simplicity and speed of channel communications 8the flexibility and inter-connectivity that characterize protocol-based network communications. 8more like a traditional circuit-switched or packet- switched network, in contrast to the typical shared- medium LAN
Business Data Communications, 4e 15 Fibre Channel Goals 8Full-duplex links with two fibers per link 8Performance from 100 Mbps to 800 Mbps on a single link (200 Mbps to1600 Mbps per link) 8Support for distances up to 10 km 8Small connectors 8High-capacity utilization with distance insensitivity 8Greater connectivity than existing multidrop channels 8Broad availability (i.e., standard components) 8Support for multiple cost/performance levels, from small systems to supercomputers 8Ability to carry multiple existing interface command sets for existing channel and network protocols
Business Data Communications, 4e 16 Fibre Channel Elements 8Nodes 8The end systems 8Includes one or more N_ ports for interconnection 8Fabric 8Collection of switching elements s between systems 8Each element includes multiple F_ ports 8Responsible for buffering and for routing frames between source and destination nodes
Business Data Communications, 4e 17 Fibre Channel Protocol Architecture 8FC-0 Physical Media: Includes optical fiber, coaxial cable, and shielded twisted pair, based on distance requirements 8FC-1 Transmission Protocol: Defines the signal encoding scheme 8FC-2 Framing Protocol: Defines topologies, frame format, flow/error control, and grouping of frames 8FC-3 Common Services: Includes multicasting 8FC-4 Mapping: Defines the mapping of various channel and network protocols to Fibre Channel
Business Data Communications, 4e 18 Wireless LANS 8LAN extension 8Wireless network connected to a main wire-based network 8Cross-building interconnect 8Point-to-point link between networks in separate buildings 8Nomadic access 8Wireless link between a LAN hub and a mobile data terminal 8Ad hoc networks 8a peer-to-peer network (no centralized server) set up temporarily to meet some immediate need.
Business Data Communications, 4e 19 Wireless LAN Requirements 8Throughput 8Number of nodes: 8Connection to backbone LAN 8Service area 8Battery power consumption 8Transmission robustness and security 8Co-located network operation 8License-free operation 8Handoff/roaming 8Dynamic configuration
Business Data Communications, 4e 20 IEEE 802.11 Standards 8Association/Re-Association/Disassociation 8Authentication 8Privacy 8Physical Media 8Infrared at 1 or 2 Mbps at a wavelength of 850-950 nm 8Direct-sequence spread spectrum in the 2.4-GHz ISM band 8Frequency-hopping spread spectrum in the 2.4-GHz ISM band, at data rates of 1 and 2 Mbps.