Page 94 - DLIS408_INFORMATION_TECHNOLOGY-APPLICATIONSL SCIENCES

Unit 8: Network Media

3Com’s 3+Share, Microsoft’s LAN Manager and IBM’s LAN Server- but none of these were Notes
particularly successful.
During the same period, Unix computer workstations from vendors such as Sun Microsystems,
Hewlett-Packard, Silicon Graphics, Intergraph, NeXT and Apollo were using TCP/IP based network.
Although, this market segment is now much reduced, the technologies developed in this area
continue to be influential on the Internet and in both Linux and Apple Mac OS X networking-and
the TCP/IP protocol have now almost completely replaced IPX, AppleTalk, NBF, and other protocols
used by the early PC LANs.
Cabling

Early LAN cabling had always been based on various grades of coaxial cable. However, shielded
twisted pair was used in IBM’s Token Ring implementation, and in 1984 Star LAN showed the
potential of simple unshielded twisted pair by using Cat3-the same simple cable used for telephone
systems. This led to the development of 10Base-T (and its successors) and structured cabling which
is still the basis of most commercial LANs today. In addition, fiber-optic cabling is increasingly
used in commercial applications.
As cabling is not always possible, wireless Wi-Fi is now the most common technology in residential
premises, as the cabling required is minimal and it is well suited to mobile laptops and smart
phones.

Technical Aspects
Network topology describes the layout pattern of interconnections between devices and network
segments. Switched Ethernet has been for some time the most common Data Link Layer and
Physical Layer implementation for local area networks. At the higher layers, the Internet Protocol
(TCP/IP) has become the standard. Smaller LANs generally consist of one or more switches linked
to each other, often at least one is connected to a router, cable modem, or ADSL modem for Internet
access.
Larger LANs are characterized by their use of redundant links with switches using the spanning
tree protocol to prevent loops, their ability to manage differing traffic types via quality of service
(QoS), and to segregate traffic with VLANs. Larger LANs also contain a wide variety of network
devices such as switches, firewalls, routers, load balancers, and sensors.

Task Write short note on LAN.

LANs may have connections with other LANs via leased lines, leased services, or by tunneling
across the Internet using virtual private network technologies. Depending on how the connections
are established and secured in a LAN, and the distance involved, a LAN may also be classified as
metropolitan area network (MAN) or wide area networks (WAN).

8.1.1 Advantages and Disadvantages of Local Area Network

Advantages
1. Easier to maintain than a WAN
2. More secure
3. Better connectivity
4. Often easier to configure than a WAN.

Disadvantages
1. You often only have 1(one) access point.
2. It limits the Area.

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