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
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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
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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
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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.
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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.
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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.
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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.
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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.
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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
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LAN/WAN History: 1970s
§ 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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LAN/WAN History: 1980s
§ 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
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LAN/WAN History: 1990s
§ ARPANET retired§ SS7 technology§ NSFNET opened to commercial use§ First cyberbank§ Internet service providers§ Over 16 million Internet hosts
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LAN/WAN History: 2000s
§ IPv6 used for Internet2 backbone communications§ Video and radio capability§ Prices of 1-Gbps devices fall as
competition increases
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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.
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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
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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
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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
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Networking Devices