BA Telecommunications and Networking Dr. V.T. Raja Oregon State University

Outline Introduction Introduction  Analogy with effective human communication 5-layer Network Model 5-layer Network Model A theoretical framework for better understanding the Internet

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

Network Design How to support full connectivity? Design the most economic internetwork between “end-user nodes” and an existing WAN Design the most economic internetwork between “end-user nodes” and an existing WAN Usernode WAN

Network Design Find an economic internetworking solution Usernode A direct connection to a WAN backbone node Usernode Connection via multiplexers

Example 1

Example 2

Example 3

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

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: HTTP (Hyper Text Transfer Protocol) operates at the Application Layer. (Example of an application layer address: TCP (Transmission Control Protocol) operates at the Transport Layer. (Example of a transport layer default port address/port ID: 80 (Web); 25( )) TCP (Transmission Control Protocol) operates at the Transport Layer. (Example of a transport layer default port address/port ID: 80 (Web); 25( ))

Protocols and addresses used at different layers of the 5-layer network model IP (Internet Protocol) operates at the Network Layer. IP (Internet Protocol) operates at the Network Layer. (Example of an IP address: ) Ethernet operates at the data link layer. Ethernet operates at the data link layer. (Example of a DLL address: 00-B0-D0-B ) In wired media, twisted pair, coaxial and fiber optic cables form the physical layer. In wired media, twisted pair, coaxial and fiber optic cables form the physical layer.

Application and Transport Layers User interfaces with application software using: User interfaces with application software using:  Application layer (e.g., web/ ) address Transport layer’s major function is: 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 #Packet # Source/Destination Port IDSource/Destination Port ID

Layer 3 – Network Layer Major functions of IP at network layer are Addressing and Routing. Major functions of IP at network layer are Addressing and Routing. Internet Protocol prepares IP header. Contents of IP header include: Internet Protocol prepares IP header. Contents of IP header include: Source/Destination IP Address and Routing Information

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

Layer-2: Data Link Layer Major functions of Data Link Layer are: 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 DL layer appends a DL header and DL Trailer

Layer 1 - Physical Layer Wired Media/Wireless Media: Examples Wired Media/Wireless Media: Examples  Twisted pair; Coaxial; Fiber Optic Cables  Microwave; Satellites and Cell phones Internetworking Devices: Examples Internetworking Devices: Examples  Hubs; Multiplexers  DSL/Cable Modems  Switches; Routers