They are the means of sharing files and common resources such as printers. They provide access to wide area networks, host computers, and servers.
LANs started out as narrow-range systems, but the enterprise network of today has evolved into a network of interconnected LANs.
By definition, a LAN is a network dedicated to a single organization, limited in range, and connected by a common communication technology.
local area network technology A LAN has the following characteristics:
A restricted range.
share a common transmission medium.
A network operating system (NOS)
NIC has the following functions:
Physical interface to the transmission medium.
Monitors the busy/idle status of the network.
Buffers/device to the speed of the network
Transmitted data stream into frames for transmission
On the network
Errors and collisions
LANs can be classified according to four cruteria:
Access Methods LAN access methods: contention or noncontention. CSMA/CD
Modulation Methods In the first, baseband, other method, broadband,
Transmission Media All of the transmission media used in other networks:
twisted pair wire
radio, and infrared
802.1 Overview document containing the reference model, and glossary 802.1b Standard for LAN/WAN management, Virtual bridged LANs 802.2 Logical link control 802.3 100 mb/s contention bus standard 10/100-Base-T 802.3 Gigabit Ethernet, Power over Ethernet (FOIRL) Full duplex Ethernet 802.4 Token bus standard 802.5 Token ring standard 4 Mbps over unshielded twisted pair 802.6 Metropolitan area network DQDB 802.7 Broadband LAN recommended practices 802.8 Fiber optic contention network practices 802.9 Integrated voice and data LAN 802.10 Interoperable LAN Security 802.11 Wireless LAN standard 802.12 Contention bus standard 100VG AnyLAN
802.3 Ethernet standard
802.3 ETHERNET STANDARDS Fast Ethernet LAN Traffic Prioritization Gigabit Ethernet 10 Gigabit Ethernet Power over Ethernet (PoE)
Power over Ethernet (PoE)
Class 0: (the default, when a device’s class is unknown) 15.4 W
Class 1: 4 W
Class 2: 7 W
Class 3: 15.4 W
Bridging and Switching
NETWORK OPERATING SYSTEMS
Application program to the computers operating system
Information transfer between the network and the server
Manage security on the network
Directly attached to the users personal computers.
Network administrator can manage the network.
inherent in Microsoft’s Windows printers, disk etc…
a printer, data or print job, others are
attached to their computer
all files are storedon a server,
user’s disk, modify and save it to their own hard disk.