LOCAL AREA NETWORK (LAN) TECHNOLOGY
• 10/100/1000 Mbps Ethernet
• 100 Mbps FDDI
• 155/620 Mbps ATM
• 4/10/45 Mbps Wireless
What is a Protocol?
• A protocol is a set of rules that
governs the communications between computers on a network.
• These rules include guidelines that
regulate the following characteristics of a network:
– access method.
– allowed physical topologies.
– types of cabling.
–
speed of data transfer.
Protocol (communications protocol)
= standards
that specifically address how the devices on a network communicate, i.e
– How the data is packaged for
transmission
– How receiving devices acknowledge
signals from sending devices
– How errors are detected and handled
Logical topologies are bound to network
protocols and describe
how data is moved across the network.
• Ethernet, LocalTalk,Token ring for
wired networks
• TCP/IP and WAP for internet
• WiFi for wireless networks
• Bluetooth, for short range wireless
network
Ethernet
- the most widely used wired networks
protocol
- Early Ethernet network were half
duplex, uses an access method called CSMA/CD (Carrier Sense Multiple
Access/Collision Detection), a system where Detection), each computer listens
to the cable before sending anything through the network to avoid collisions.
- Since 1997 Ethernet uses full duplex
communication, that does not require listening to other messages and no
collisions occur.
- The Ethernet protocol allows for
linear bus, star, or tree topologies. Data can be transmitted over wireless
access points, twisted pair, coaxial, or fiber optic cable.
- Early Ethernet protocols (10BASE-T)
support transmissions rate 10 Mbps
- Today:
– 100BASE-T or 100BASE-TX – 1000Mbps
(1Gbps
– 10Gigagbit Ethernet – 10Gbps
LocalTalk
-a network protocol that was developed
Macintosh computers.
- used a method called CSMA/CA (Carrier
Sense Multiple Access with Collision Avoidance), where a computer signals its
intent to transmit before it actually does so.
- allows for linear bus, star, or tree
topologies using twisted pair cable.
- disadvantage : slow speed (only 230
Kbps).
Token Ring
- developed by IBM in the mid-1980s.
- access method involves token-passing.
- the computers are connected so that
the signal travels around the network from one computer to another in a logical
ring.
- A single electronic token moves
around the ring from one computer to the next. If a computer does not have information
to transmit, it simply passes the token on to the next workstation. If a
computer wishes to transmit and receives an empty token,
it attaches data to the token. The token then proceeds around the ring until it
comes to the computer for which the data is meant- the data is captured by the
receiving computer.
-The Token Ring protocol requires a star-wired
ring using twisted pair or fiber optic cable. It can operate at transmission
speeds of 4 Mbps or 16 Mbps.
FDDI
- Fiber Distributed Data Interface - a
network protocol that is used primarily to interconnect two or more local area
networks, often over large distances.
- access method involves token-passing.
- uses a dual ring physical topology.
Transmission normally occurs on one of the rings; if a break occurs, the system
keeps information moving by automatically using portions of the second ring to
create a new complete ring.
- A major advantage of FDDI is speed.
It operates over fiber optic cable at 100 Mbps.
Cabling
- Cable is the medium through which
information usually moves from one network device to another.
- Several types of cable are commonly
used with LANs.
- In some cases, a network will utilize
only one type of cable, other networks will use a variety of cable types
Types of Cables
- Unshielded Twisted Pair (UTP) Cable
- Shielded Twisted Pair (STP) Cable
- Coaxial Cable
- Fiber Optic Cable
Unshielded Twisted Pair (UTP) Cable
- The cable has four pairs of wires
inside the jacket. Each pair is twisted
with a different number of twists per
inch to help eliminate interference
from adjacent pairs and other
electrical devices.
Categories
TYPES
|
USE
|
CATEGORY 1
|
VOICE (Wayer Telefon)
|
CATEGORY 2
|
Data t0 4 Mbps (LocalTalk)
|
CATEGORY 3
|
Data to 10 Mbps (Ethernet)
|
CATEGORY 4
|
Data to 20 Mbps (16 Mbps Token Ring)
|
CATEGORY 5
|
Data to 100 Mbps (Fast Ethernet)
|
UTP Cable Standards
Cat 3 UTP
|
to carry data up to
10Mbit/s.
standard cable for
use with Ethernet 10Base‐T.
|
Cat 5 UTP
|
to carry Ethernet up to 100Mbit/s and ATM up to 155Mbit/s.
standard cable for use with Ethernet
100Base‐TX.
|
Cat 5e UTP
|
an enhanced version of Cat UTP.
to carry data up to 1000Mbit/s.
standard cable for use with Ethernet 1000Base‐T.
used to extend the distance of 100Base‐TX cable runs up to
350
meters.
|
Cat 6 UTP
|
similar to Cat 5 UTP, except that it is designed and
manufactured to
even stricter standards.
|
Unshielded Twisted Pair (UTP) Cable
The
standard connector for unshielded twisted pair cabling is an RJ-45 connector.
RJ=Registered Jack
A
disadvantage of UTP is that it may be susceptible to radio and electrical
frequency interference.
Shielded
Twisted Pair (STP) Cable
STP
is
a type of cable consists of two individual wires wrapped in a foil shielding to
help provide a more reliable data communication.
•
suitable
for environments with electrical interference;
•
however,
the extra shielding can make the cables quite bulky.
•
often
used on networks using Token Ring topology.
CO-AXIAL
CABLE
- Coaxial cabling has a single copper conductor at its center.
- A plastic layer provides insulation between the center conductor and a braided metal shield.
- The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.
Coaxial
Cable Connectors
•
The
most common type of connector used with coaxial cables is the Bayonet Neill-Concelman
(BNC) connector
•
Different
types of adapters are available for BNC connectors, including a T-connector, barrel
connector, and terminator.
FIBRE OPTICS
•
consists
of a center glass core surrounded by several layers of protective materials
•
It
transmits light rather than electronic signals eliminating the problem of
electrical interference.
•
ideal
for certain environments that contain a large amount of electrical
interference..
•
able to
transmit signals over much longer distances than coaxial and twisted pair.
Summary
of Ethernet cabling
Specification
|
Cable Type
|
Maximum length
|
10BaseT
|
Unshielded Twisted Pair
|
100 meters
|
10Base2
|
Thin Coaxial
|
185 meters
|
10Base5
|
Thick Coaxial
|
500 meters
|
10BaseF
|
Fiber Optic
|
2000 meters
|
Cable
& topology
Topologi Fizikal
|
Kabel Umum
|
Protokol Umum
|
Linear Bus
|
Coax
Twisted Pair
Fiber
|
Ethernet
Local Talk
|
Star
|
Twisted Pair
Fiber
|
Ethernet
Local Talk
|
Star-Wired Ring
|
Twisted Pair
|
Token Ring
|
Tree
|
Coax
Twisted Pair
Fiber
|
Ethernet
|
NETWORK
OPERATING SYSTEM (NOS)
•
Software
that controls a network and its message (e.g. packet) traffic and queues,
controls access by multiple users to network resources such as files, and
provides for certain administrative functions, including security.
• coordinate the
activities of multiple computers across a network.
•
acts as
a director to keep the network running smoothly.
• A NOS is not the
same as the networking tools provided by some existing OSs, Windows XP for
instance.
•
An NOS
is an OS that has been specifically written to keep networks running at optimal
performance.
•
Some
popular NOSs include:
•
Windows
NT , IBM AIX, Sun Solaris, Windows
2000
Server, Windows Server 2003,Inferno
Novell
NetWare, Red Hat Linux, BSD
•
The two
major types of network operating systems are:
–
Peer-to-Peer
–
Client/Server
(i)
Peer to Peer
•
In a
peer-to-peer network, all computers are considered equal; they all have the
same abilities to use the resources available on the network
•
allow
users to share resources and files located on their computers and to access
shared resources found on other computers.
•
do not
have a file server or a centralized management source
•
designed
primarily for small to medium local area networks.
•
AppleShare
and Windows for Workgroups are examples of programs that can function as
peer-to-peer network operating systems.
Advantages
•
Less
initial expense - No need for a dedicated server.
•
Setup -
An operating system such as Windows XP/…) already in place may only need to be
reconfigured for peer-to peer operations.
Disadvantages
•
Decentralized
- No central repository for files and applications.
•
Security
- Does not provide the security available on a client/server network.
(ii)
Client/Server
-allow
the network to centralize functions and applications in one or more dedicated file
servers
- the
file servers become the heart of the system,
providing access to resources and providing security.
- individual
workstations (clients) have access to the resources available on the file
servers.
- Novell
Netware and Windows 2000 Server are examples of client/server network operating
systems.
Logikal Protokol
•
TCP/IP
•
AppleTalk
•
Novell
IPX
•
XNS
•
DECnet
• Banyan
Vines
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