BA 471 – Telecommunications and Networking

Dr. V.T. Raja

Oregon State University

Raja@bus.oregonstate.edu

As presented in Dr. Marshall’s BA471 class, Winter 2006

Outline

• Introduction– Analogy with effective human communication

• 5-layer Network ModelA theoretical framework for our day-to-day interactions on the Internet

Some Basic Characteristics of Effective Human Communication

• Sender/Receiver

• Messages (Words)

• Transmission MediaAir/Printed Page

• Less noisy room (or) talk loud enough

• Speak same language or have an Interpreter

Some Basic Characteristics of Telecommunication Networks

• Source; Destination – Host

• Signals (Digital/Analog) – Modulation (digital to analog)– Demodulation (analog to digital)– Done by a Modem

• Transmission Media– (Wired/Wireless)

• Communications Protocols/Standards

Wired Transmission Media

• Coaxial (like cable TV)• Twisted Pair

– Copper– Shielded and twisted to reduce noise

• Fiber Optic– Much faster– Able to go longer distances without a repeater– Uses light not electricity– Multi-color lights vastly increases capacity– Expensive

Wireless Transmission

• Infrared (as in a TV remote)• Radio Signals (as in microwave transmissions)• Satellites

– http://www.orbitaldebris.jsc.nasa.gov/index.html– GEOS: Geosynchronous Earth Orbiting Satellites –

stationary orbit at 22,300 miles above the Earth– LEOS: Low Earth Orbiting Satellites– Closer to the Earth and reachable from mobile

devices– 200-1,000 miles above the Earth– Not stationary, goes around the Earth in about 90

minutes– 60-70 LEOS are needed to cover the Earth

Network DesignHow to support full connectivity?

Design the most economic internetwork Design the most economic internetwork between “end-user nodes” and an existingbetween “end-user nodes” and an existing WAN (Wide Area network e.g. the Internet)WAN (Wide Area network e.g. the Internet)

Usernode

Usernode

Usernode

Usernode Usernode

Usernode

Usernode

Usernode

UsernodeUsernode

WAN

Network DesignFind an economic internetworking solution

Usernode

Usernode

Usernode

Usernode

UsernodeUsernode

A direct connection toa WAN backbone node

Usernode

Usernode

Usernode

Usernode

Usernode

Usernode

Connection viamultiplexers

Some Network Design IssuesMajor Cost Components

Acquisition and installation costs of a MUXAcquisition and installation costs of a MUX Cost of high bandwidth link between MUX Cost of high bandwidth link between MUX

and WAN (Internet)and WAN (Internet) Cost of low bandwidth link between end-Cost of low bandwidth link between end-

user node and MUXuser node and MUX

A Multiplexer (MUX) consolidates several (many?) slow links A Multiplexer (MUX) consolidates several (many?) slow links (local networks or single nodes) connecting them to a fast link (local networks or single nodes) connecting them to a fast link (e.g. a WAN such as the Internet).(e.g. a WAN such as the Internet).

Network Design ManagementHow to design a feasible and economical internetwork?

Find an optimal number of MUXs to interconnect all Find an optimal number of MUXs to interconnect all given user nodes to some existing WAN such that ... given user nodes to some existing WAN such that ...

All user nodes are connectedAll user nodes are connected User communication requirements are satisfiedUser communication requirements are satisfied Capacity constraints on each MUX is not violatedCapacity constraints on each MUX is not violated Total internetworking costs are minimizedTotal internetworking costs are minimized Topology issues are consideredTopology issues are considered

Example 1

Example 2

Example 3

Theoretical Framework: 5-layer network model

• Application Layer (Layer-5)

• Transport Layer

• Network Layer

• Data Link Layer

• 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:

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)

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

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

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

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

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

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