CS/IS 465: Data Communication and Networks 1 CS/IS 465 Data Communications and Networks Lecture 28 Martin van Bommel

CS/IS 465: Data Communication and Networks 2 High-Speed & Wireless LANs Why? –Extraordinary growth in speed, power, and storage capacity of PCs –Increasing use of LANs as computing platforms –Low speed not capable of supporting requirements Examples –Server farms - multiple centralized servers –Power work groups - e.g. CAD company –High-speed backbones

CS/IS 465: Data Communication and Networks 3 LAN Generations First - CSMA/CD and Token Ring –terminal-to-host connnectivity –client-server at moderate data rates Second - FDDI and others –backbone LANs and high-performance stations Third - ATM LANs –multiple guaranteed high-speed classes of service –multimedia applications

CS/IS 465: Data Communication and Networks 4 Fast Ethernet CSMA/CD operating at 100 Mbps Easy to integrate with existing systems 100BASE-X - two simplex links b/w nodes Can use UTP (100BASE-TX) but requires two lines between stations Can use Fiber (100BASE-FX)

CS/IS 465: Data Communication and Networks 5 Fast Ethernet Configuration 100BASE-T uses star-wire topology All stations connected to central point using multiport repeater (broadcast method) Repeater, not stations, detects collisions and sends jam signal on all ports Repeaters connected with bridges

CS/IS 465: Data Communication and Networks 6 Fast Ethernet Full-duplex Mode Traditional Ethernet is half-duplex Two links b/w stations allows full-duplex NICs must support full-duplex mode Switched hub must be used - determines path for frame No collisions ever occur

CS/IS 465: Data Communication and Networks 7 Mixed Ethernet Can mix 10-Mbps and 100-Mbps LANs Slow stations attach to 10-Mbps hubs Hubs connected to 100-Mbps hubs High-speed servers connected to 100-Mbps See Figure 15.4Figure 15.4

CS/IS 465: Data Communication and Networks 8 Gigabit Ethernet Still under development (started late 1995) Retains CSMA/CD protocol and Ethernet format, ensuring smooth upgrade path Uses optical fiber over short distances 1-Gbps switching hub provides backbone connectivity for central servers and high-speed workgroup hubs - Figure 10-5Figure 10-5

CS/IS 465: Data Communication and Networks 9 FDDI Fiber Distributed Data Interface Oldest high-speed LAN standard Token ring MAC protocol with early token release (frame occupies only small part of ring with high-speed) Piggy-back frames by claiming early- release token

CS/IS 465: Data Communication and Networks 10 FDDI (2) 100 Mbps optical fiber 100 Mbps category 5 UTP or STP Respectable market share ATM LANs better suited to multimedia traffic and to integrate with ATM WANs

CS/IS 465: Data Communication and Networks 11 ATM LANs Several types –Gateway to ATM WAN ATM switch acts as router to ATM WAN –Backbone ATM switch ATM switch(es) interconnect other LANs –Workgroup ATM high-performance stations connect directly to ATM switch –Mixture of types on internet

CS/IS 465: Data Communication and Networks 12 Backbone ATM LAN Local ATM network consists of switches interconneted with high-speed point-to-point links running ATM rates of 155 & 622 Mbps LANs directly connect to ATM switches ATM switch performs buffering, speed and protocol conversion Figure End systems still limited by shared mediums

CS/IS 465: Data Communication and Networks 13 ATM Hub Each ATM hub includes number of ports Ports operate at different rates and protocols Each end system has dedicated point-to- point link with hub - FigureFigure Existing LAN hardware can be used on LAN systems while introducing ATM LAN Hub requires complex protocol conversions

CS/IS 465: Data Communication and Networks 14 Pure ATM LAN End systems attach directly to ATM network ATM protocols implemented No conversions required

CS/IS 465: Data Communication and Networks 15 ATM Compatibility Issues Interaction between ATM-based station and legacy-based station Interaction between two stations using same legacy protocol but communicating via ATM Interaction between two stations using different legacy protocols via ATM Solution - bridge or router type ATM switch