cis485_lect1

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LECTURE 1:

Overview of LAN/WAN Networking

CIS 485 Local Area Networks

Fall 2003Instructor: Prof. Song Xing

Department of Information SystemsCalifornia State University, Los Angeles

Local Area Networks 2

Outlines

§ Define and identify the different types of networks§ Describe the history of LANs and WANs§ Discuss LAN and WAN integration,

including the basic functions of bridges, routers, gateways, and switches

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Computer Network

§ System of computers, print devices, and computer software linked by communications cabling or radio waves§ Typically classified according to:§ Reach and complexity§ Protocols and topologies


Two Types of Networks

§ Terminal Network§ Consists of a single host computer with attached

terminals.§ Host computers do all or most of the processing,

and the terminals imply act as input/output (I/O) devices through which a person gains access to the host’s applications.

§ Network of Computers§ Two or more nodes connected by a data

communications medium. § Individual nodes may have terminals attached to

them.§ A single node on this network can look just like the

terminal network.

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Network Communications


Three Network Subtypes

§ Local Area Networks (LAN)§ Metropolitan Area Networks (MAN)§ Wide Area Networks (WAN)

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Local Area Networks (LAN)

§ Series of interconnected computers, printing devices, and other computer equipment that share hardware and software resources§ Service area usually limited to a given office

area, floor, or building § A LAN services a limited geographic area at

high speeds—usually 10 million bits per second or higher. § All components of the LAN are commonly

owned by the organization that uses it.


Example of a LAN

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Metropolitan Area Networks (MAN)

§ A high-speed network covering wider distances than LAN§ Spans distances of approximately 100 miles;

Links multiple LANs in a large city or metropolitan region§ MAN speeds are typically 100 Mbps or

higher.§ A MAN is typically implemented by the fiber

distributed data interface (FDDI). It operates at 100 Mbps over fiber optic cable for distances up to 200 kilometers.


Example of a MAN

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Wide Area Network (WAN)

§ Far-reaching system of networks that usually extends over 30 miles and often reaches across states and continents§ However, some WANs are confined to a

limited geographic area, like a LAN.


LAN/MAN/WAN Comparison

Limited—typically up to 2,500 meters or 2 miles

High—typically in excess of 10 Mbps—10,100 and 1,000 are standard

Locally owned—twisted-pair wires, fiber optic cable, wireless (not satellite)

Can be any, but most are desktop computers

Limited—typically up to 200 kilometers or 100 miles

High—typically 100 Mbps

Locally owned and common carrier—twisted-pair wires, fiber optic cable

Can be any, but most are desktop computers and minicomputers

Unlimited

Slower—usually 1.5 Mbps

Locally owned and common carrier—twisted-pair wires, coaxial cable, fiber optic cable, wireless to include satellite

Can be any, but most are desktop computers

Distance

Speed

Media

Nodes

LAN MAN WAN

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Network Classification§ Enterprise network, an organization’s complete

network§ Combination of LANs, MANs, or WANs that provides users

with an array of computer and network resources to complete different tasks

§ With the advent of LANs, many organizations installed departmental LANs to improve the productivity of work groups.

§ To take a benefit to having users on one LAN communicate with users or applications on other LANs or on the WAN, the various networks were connected together to form one corporate-wide network, the enterprise network.


Enterprise Network

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The Internet

§ An internet (with a lowercase ‘i’) is the interconnection of two or more networks. An enterprise networks just described is an example of an internet.§ The Internet (with an uppercase ‘I’) is a

specific instance of an internet. § The Internet is a global network of networks.

It is made up of hundreds of networks, thousands of nodes, and millions of users throughout most countries of the world.


Identifying a Network Type

§ Communications medium§ Wire cable, fiber-optic cable, radio waves,

microwaves§ Protocol§ How networked data is formatted into discrete

units§ How each unit is transmitted and interpreted

§ Topology§ Physical layout of cable and logical path

§ Network type§ Private versus public

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LAN/WAN History: 1960s

§ First WAN§ Hypertext§ Use of fiber optics for phone signals§ Beginning of ARPANET§ Packets and packet switching§ UNIX§ Telecommunications equipment§ First IMP prototype



§ Ethernet§ ARPANET - 15 sites§ E-mail§ Terminal emulation§ International

connections to ARPANET

§ Telecommunications conversion from analog to digital§ X.25§ First wireless

gateway§ Internet Protocol § LSI and VLSI chips§ ICCB

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§ BITNET§ IBM’s PC§ Dial-up modem

technology§ TCP and IP adopted

as protocol suite for ARPANET§ First PC LAN§ Arrival of Internet

§ Internetwork hosts§ 5,000 in 1986§ 100,000 in 1989

§ “Cyberspace”§ T-carrier services§ NFSNET§ Desktop authoring

and multimedia§ SNMP



§ ARPANET retired§ SS7 technology§ NSFNET opened to commercial use§ First cyberbank§ Internet service providers§ Over 16 million Internet hosts

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§ IPv6 used for Internet2 backbone communications§ Video and radio capability§ Prices of 1-Gbps devices fall as

competition increases


LAN/WAN Integration

§ Becoming more advanced through networking devices§ Bridges§ Routers§ Gateways§ Switches§ Hubs§ Repeaters

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Internetworking

§ Many times it is necessary to connect a local area network to another local area network or to a wide area network.§ Local area network-to-local area network

connections are often performed with a bridge-like device.§ Local area network-to-wide area network

connections are usually performed with a router.§ A switch can be used to interconnect

segments of a local area network.


Why Interconnect?

§ To separate / connect one corporate division with another.§ To connect two LANs with different protocols.§ To connect a LAN to the Internet.§ To break a LAN into segments to relieve

traffic congestion.§ To provide a security wall between two

different types of users.

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Bridges

§ Connect different LANs or LAN segments using the same access method


Routers

§ Connect networks having the same or different access methods and media§ Forward packets and frames to

networks by using a decision-making process based on:§ Routing table data§ Discovery of most efficient routes§ Preprogrammed information from network

administrator

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Routers


Gateways§ Enable communications between two different types

of networked systems

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Switches§ Hub: multi-port repeater§ Switch: combines the

functions of a bridge and a hub§ Link network

segments§ Forward and filter

frames between segments§ Done in hardware


Networking Devices

Documents

cis485_lect1