1. BA 471 – Telecommunications and Networking Dr. V.T. Raja Oregon State University Raja@bus.oregonstate.edu

2. Outline Introduction –Analogy with effective human communication 5-layer Network Model A theoretical framework for our day-to-day interactions on the Internet

3. Some Basic Characteristics of Effective Human Communication Sender/Receiver Messages (Words) Transmission Media Air/Printed Page Less noisy room (or) talk loud enough Speak same language or have an Interpreter

4. Some Basic Characteristics of Telecommunication Networks

5. Theoretical Framework: 5-layer network model Application Layer (Layer-5) Transport Layer Network Layer Data Link Layer Physical Layer (Layer-1)

6. Protocols and addresses used at different layers of the 5-layer network model HTTP (Hyper Text Transfer Protocol) operates at the Application Layer. – Example of an application layer address: www.bus.oregonstate.edu www.bus.oregonstate.edu TCP (Transmission Control Protocol) operates at the Transport Layer. –Example of a transport layer default port address/port ID: 80 (Web); 25(E-mail)

7. Protocols and addresses used at different layers of the 5-layer network model IP (Internet Protocol) operates at the Network Layer. – Example of an IP address: 128.192.64.224 Ethernet operates at the data link layer. –Example of a DLL address: 00-B0-D0-B4-54-13

8. Application and Transport Layers User interfaces with application software using: –Application layer (e.g., web/e-mail) address Transport layer’s major function is: –Packetizing Breaking large messages into smaller packets at source Reassembling packets at final destination Creates/appends TCP header –Packet # –Source/Destination Port ID

9. Network Layer Major functions of IP at network layer are –Addressing and –Routing IP prepares IP header which contains: –Source/Destination IP Address and –Routing Information

10. Network Layer (Continued) Addressing –DHCP (Dynamic Host Control Protocol) Server Assigns IP addresses to client machines requesting an IP address –DNS (Domain Name Service) Server Similar to directory assistance – used for finding destination IP addresses. Routing –Routing tables; Routers (Tracert); Routing Protocols

11. Data Link Layer Major functions of Data Link Layer are: –Media Access Control Handling message collisions –Error Detection –Error Correction –Message Delineation Identifying beginning and ending of packets – since all computer transmissions go out as 0s and 1s over the physical layer DL layer appends a DL header and DL Trailer

12. Physical Layer Wired Media/Wireless Media: Examples –Twisted pair; Coaxial; Fiber Optic Cables –Microwave; Satellites and Cell phones Internetworking Devices: Examples –Hubs; Multiplexers –DSL/Cable Modems –Switches; Routers