1. Networks CSCI-N 100 Dept. of Computer and Information Science

2. The Basics Early years networks were scarce Early PCs worked as standalone Interaction limited to one person with software Engineers anticipated networking has advantages Bob Metcalf, 1975, Ethernet

3. Network Classification PAN – personal area network NAN – neighborhood area network LAN – local area network MAN – metropolitan area network WAN – wide area network

4. PAN – personal area network Personal devices Usually within 30 feet No cables or wires Example – wireless transmission of data from computer to PDA, cell phone, printer

5. NAN – neighborhood are network Limited within a geographic area Spread over several buildings Example - local Starbucks

6. LAN – local area network Limited to a very small geographic area Usually one building Can be wired or wireless Type of network most likely to work with in school, business, home Example – school computer labs, home networks

7. MAN – metropolitan area network Public High speed access Voice and data transmission Range about 50 miles Example – ISP, cable television, local telephone

8. LAN Standards Standard by the Institute of Electrical and Electronic Engineers (IEEE) Designation number refers to standard Helps to identify compatible network technologies Ethernet, WiFi for home, business

9. Connections Node – point on a network Network interface card (NIC) – usually circuitry built in- - Add on slot on system board, USB port, notebook PC slot

10. Client/Server – Why not both Client – The user – Ask for information – Data sent to server Server – Responds to the user (client) – Application server – Print server Sends back data

11. Network topology Star Ring Bus Mesh Tree Hybrid T wo types of topologies: Physical and Logical Physical topology of a network refers to the layout of cables, computers and other peripherals network cables coming out of every computer that is part of the network, then those cables plug into a hub or switch Logical topology is the method used to pass the information between the computers the network works with all the computers talking (think of the computers generating traffic and packets of data going everywhere on the network) computers will be talking to each other and the direction of the traffic is controlled by the various protocols (like Ethernet)

12. Star Reduces risk of failure. Expanding the network is simple. Managing the network is centralized. If the hub breaks down, the system fails.

13. Ring All clients have equal access to data. This gives even performance under heavy demand conditions. Difficult to add another host to the ring.

14. Bus Simple, cheap, reliable, efficient use of cable. Isolating problems is hard. One error can halt the system.

15. Mesh This redundancy allows the system to continue if some connections fail. However, multiple connections are expensive.

16. Tree Point-to-point wiring for individual segments. Supported by several hardware and software venders Overall length of each segment is limited by the type of cabling used. If the backbone line breaks, the entire segment goes down. More difficult to configure and wire than other topologies

17. Hybrid – Star and Bus Network expansion is simple. If one client fails, the entire network does not fail. If one hub fails, all connections to that hub fail, although other hubs continue to function.

18. Devices Any electronic device that broadcast network data Can include – Hubs, links 2 or more nodes of wired network – Routers, ships data from one network to another – Switches, only sends data to specified destination – Gateways, used to join 2 networks using different protocols, different address ranges – Bridges, connects 2 similar networks without regard to network format – Repeaters

19. References Slide 11 – http://www.firewall.cx/topologies.php Slides12, 13, 14 – http://www.geocities.com/richard_leigh_bowles/theory/summaries/ntf/chap1.htm http://www.geocities.com/richard_leigh_bowles/theory/summaries/ntf/chap1.htm Slide 15 – http://chauncy-ict.pbwiki.com/Mesh%20Topology http://chauncy-ict.pbwiki.com/Mesh%20Topology Slide 16 – http://fcit.usf.edu/Network/chap5/chap5.htm#TreeNetwork http://fcit.usf.edu/Network/chap5/chap5.htm#TreeNetwork