Messinger - MIS 4477 - Fitzgerald

MIS 4477
Network and Security Infrastructure
JAKE MESSINGER (jake@uh.edu)

Fitzgerald/Dennis Chapter 1: Introduction to Data communications (class 2)

Author's PowerPoint Presentation
Student Companion Site: Chapter 1
Networking Labs

Why study Data Communications?

We are now in an Information Age
The value is in putting the sender and the receiver closer together in time - instant gratification
Data Communications is a global area of study

History of Communications in America

1837 - Samuel Morse exhibited a working telegraph system. (first electronic data information network)
1843 - Alexander Bain patented a printing telegraph (first fax machine)
1876 - Alexander Graham Bell invented the first telephone capable of practical use.
1879 - first private manual telephone switchboard (first PBX)
1880 - first pay telephone
1892 - Canadian government began regulating telephone rates.
1910 - ICC regulated interstate telephone business.
1915 - First transcontinental telephone serve and first transatlantic voice connections.
1934 - Communications Act transferred regulation of interstate telephone traffic from ICC to FCC.
1947 - transistor invented in Bell Labs
1951 - first direct long distance dialing
1962 - first international satellite telephone call
1968 - Carterfone court decision allowed non-Bell equipment to connect to Bell System Network. (major battle won)
1969 - Picture-fone service began: demonstrated in 2001 A Space Odyssey
1970 - Permitted MCI to provide limited long distance service in competition to AT&T.
1984 - deregulation of AT&T (break-up of the Bell monopoly, RBOCs born)
1980s - public service of digital networks
1990s - cellular telephones commonplace
1996 - U.S. Congress enacted the Telecommunications Act of 1996
1997 - International agreement signed by 68 countries to reduce regulation in Telecom markets
2000’s - Phone numbers become portable. VoIP gaining popularity
2010’s - Cell phone usage overtakes land lines. Smart phones overtake stand alone devices: GPS, cameras, remotes

The 1996 Telecomm act changed the face of communications. It superseded ALL previous Federal communications laws INCLUDING the 1984 AT&T breakup. ANYONE could become a phone company and offer service at ANY level to ANYWHERE. RBOC's can now offer long distance. They were previously prevented from doing so.

History of Information Systems:

1950s - Computer systems used batch processing with discrete files.
1960s - Data communication across telephone lines became more commonplace.
1960s-1970s - online real-time systems were developed.
1980s - Widespread adoption of personal computer.
1990s - More than 60 percent of all PCs in the U.S. were networked.
2000's - If your PC isn’t networked, then it is useless.

Over the years, networking has transformed the way companies do business. Wal-Mart can attribute its great success to its severe level of networking and INSTANT data transfer of sales, inventory, pricing awareness, consumer behavior. Virtually every employee is connected to the Wal-Mart network in real-time.

History of the Internet

The evolution of the Internet was quite different than communications & info systems:

It is not widely regulated.
Started because of Sputnik, DARPA
Nobody "owns" or controls the entire Internet.
EVERY communications company offers some sort of Internet service

· Anyone with access to the Internet can communicate with any computer on the Internet.

Thousands of "ISPs" offer Internet services all over the US.

Update: ISP’s extinct:

· Dial-up is dead

· Connections are now hardwired or wireless and not “customer” switched, i.e. DSL, Cable and 4G.

· Service is primarily from major network providers, Comcast, ATT, Clear, Verizon, Level 3

Domain Naming

· Needed because IP addresses too hard to remember and manage.

· Addresses consist of two parts, the host name and its domain.
computer.domain (called the FQDN)

· Each TLD has an addressing board that assigns addresses for its domain.

Original USA/Canadian Domain Names:

EDU: Only for accredited 4 year colleges or universities
COM: commercial companies
GOV: reserved for government, e.g. usps.gov (us post office)
MIL: military domain
ORG: reserved for societies and organizations.
NET: commercial companies that are primarily network service providers

International Domain Names examples:

US: United States
CA: Canada
AU: Australia
UK: Great Brittain
DE: Germany
FR: France

There is a 2 letter code for every country participating in the Internet including government protectorates and island nations.

New TLD's (Top Level Domains) are being used with more on the way, INFO, BIZ, NAME

Components of a Network

Network Nodes

Server (or a host computer) is a central computer in the network storing software, data or provides access to a service that can be accessed by clients. Typically, servers are "headless".
Client is the input/output hardware device at the other end of a communication circuit. It typically provides users with access to the network and to the data and software on the server. It is the machine that users sit at.
Front End Processor is a specialized computer with special software and hardware which controls a computer network. It is sometimes used to provide an interface between outside users and an internal and sometimes proprietary system, e.g. Fedex's web servers that allow you to track and ship packages are Front End Processors that attach to the "real" servers.
Host Computer is the central processing unit (CPU) which processes the users request. On most networks, ANY machine with a CPU is considered a host, even client computers.
File Server is a computer in which data is stored for a network (usually LAN) (also other specialized servers possible such as mail server, security server).

Organization of Network Nodes

Hierarchical Network is a computer network which is controlled by a central host computer. Now they are called servers as every machine with a CPU is a host. In the old days, there was a host and then dumb terminals connected to it.
Peer-to-Peer network is a computer network in which computers function as equals, e.g. Lantastic and Powerlan.
Point-to-point network connects two points (e.g., a micro computer to a server), Analogy: Telephone system. Each PC on the network has a "phone" number and they all talk to each other via these numbers (or addresses).
Broadcast network (one-to-many) connects one point (e.g., a server) to many (e.g., a host computer to micro computers). Analogy: Broadcast TV. Any computer listening in can receive the data.
Multi-cast network (one-to-many) connects one point (e.g., a server) to many (e.g., a host computer to micro computers) that have been given permission to join a network, typically for a temporary period. Analogy: Teleconference: Multiple calls are made from one location to several and they are all joined together, however, only the main caller can talk. The others are only listening.

Connecting Network Nodes

Circuit: the pathway through which the messages travel (copper wire, fiber optic cable, wireless transmission, NOT necessarily a physical wire)
Repeater (hub): device used to boost the strength of a signal. Repeaters are spaced at intervals throughout the length of a communication circuit.
Bridge: connects two similar networks using the same data link and network protocols.
Gateway: connects two dissimilar networks and allows two networks of different vendors to communicate by translating one vendor’s protocol into another.
Router: connects two similar networks which have the same network protocol. It also chooses the best route between two networks when there are multiple paths between them. “Border” routers (those on the border of your LAN and your Internet connection) are referred to as Gateways even if they are not doing any protocol translation.
Firewall: combines the functions of a local switch and a router and adds security.
Switch: looks like a repeater but functions as a multi-connection router. Virtual networks can be created and network traffic can be selectively filtered.

Scope of Networks -

Network Modela -

OSI Model: 7 layer, invited by the ISO

Internet Model: More commonly used

Layer 1: Physical
Layer 2: Data Link
Layer 3: Network
Layer 4: Transport
Layer 5: Application

Layers can be grouped:

Hardware layer: Phisycal and Data Link
Internetworking Layer: Network and Transport
Application Layer: Protocols specific to the application

Messages are transmitted from sender to receiver using protocols that exist in all layers.

Network Standards.

The importance of Standards - fire hoses, power, railroad track
The Standards Making Process - Committee's - do not enforce standards, just coordinate
Common Standards - ISO, ANSI, ITU, IEEE

Future Trends

Pervasive Networking
Integration of Voice, Video, Data
New Info services

End of Lecture 2