1. Two Network Types Defined by DISTANCE LAN WAN

2. NETWORKS LAN LOCAL AREA NETWORK

3. LAN Ethernet A particular type of LAN

4. Network Components (LAN) n Workstations – microcomputers – minicomputers – workstations – mainframes – terminals – supercomputers n Servers (optional) n Media n Interfaces – circuit boards – network adapter – NIC – network interface card n Gateways – connect dissimilar parts of a network n Bridges – connect similar parts of a network

5. Media - cables n Twisted pair – inexpensive – least reliable – easiest to install – what is used in telephone lines – slow

6. Media - cables n Coaxial – more reliable – what is used in cable TV – harder to install – faster

7. Media - cables n Fiber optic – works with light waves (lasers) – most reliable – most expensive – fastest – most difficult to work with – becoming the media of choice

8. TOPOLOGIES Physical design of a network

9. Three LAN topologies: §BUS §STAR §RING

10. Bus Single cable Easy to install No server

11. Ring Single connected cable Break does not destroy all the connections Usually does not have a server

12. Star Individual cables Easiest to trouble shoot Has a server

13. Network Protocols rules for communicating Specifies - type of topology handshake synchronous/asynchronous transmission how data will be packaged

14. 3 Protocol Classifications §Polling §CSMA/CD §Token ring

15. Polling §Goes to each workstation in turn §Assures that all work stations will access §Problem if there are many workstations

16. CSMA/CD §Carrier sense multiple access with collision detection §Workstations try to seize the network when they want to access §Problem if two workstations want to access at the same time

17. Token Ring §Token - electronic device §Token circulates around network §Token is either free or has a message §If it has a message, goes to the receiver and back to sender before continuing

18. Network Software Operating system of the network

19. Resides on server Controls file transfers Controls hardware sharing Controls uploading/downloading of files May include: –electronic mail –performance analyzation software –security software –diagnostic routines

20. LAN Ethernet Most widely used type of LAN

21. Characteristics Coax cable –High volume of transmission for short distances

22. Characteristics Special hardware –Transceiver – connects nodes to network –Interface – performs data conversions from a byte to a series of bits –Repeater – strengthens and retimes the signals

23. Characteristics Uses CSMA/CD –Controller – determines when to activate communications between nodes