network hardware and physical media network hardware includes: – computers – peripherals –...
Post on 28-Mar-2015
216 Views
Preview:
TRANSCRIPT
Network Hardware and Physical Media
Network hardware includes:
– Computers– Peripherals– Interface cards and– Other equipment needed
to perform data processing and communications within the network
File servers
A very fast computer with a large amount of RAM and storage space along with a fast network interface card
The network operating system software resides on this computer
Workstations
All computers connected to the file server on a network are called workstations
Network interface cards
The network interface card (NIC) provides the physical connection between the network and the computer workstation.
Most NICs are internal with the card fitting into an expansion slot in the computer.
Three common network interface connections are Ethernet cards, Local Talk connectors and Token Ring cards
Ethernet cards
The most common Network Interface Cards are Ethernet cards
They contain connections for either coaxial or twisted pair cables, or both Twisted
pair cable
Co-axial cable
Concentrators / Hubs
A concentrator is a device that provides a central connection point for cables from workstations, servers and peripherals
Hubs are multi-slot concentrators
Switches
hubs provide an easy way to scale up and shorten the distance that the packets must travel to get from one node to another
they do not break up the actual network into discrete segments. That is where switches come in.
Switches (continued)
A vital difference between a hub and a switch is – all the nodes connected to a hub share the bandwidth among themselves.– while a device connected to a switch port has the full bandwidth all to itself.
Think of a switch as a ‘clever’ hub
Repeaters
A signal loses strength as it passes along a cable, so it is often necessary to boost the signal with a device called a repeater
A repeater might be a separate device, or might be part of a concentrator
Bridges
A bridge is a device that allows you to segment a large network into two smaller, more efficient networks
Router
An example of a network with a bridge
Internet
Segment Node
Hub
Hub
Bridge
Routers
A router translates information from one network to another
The router directs traffic to prevent “head-on” collisions
If you have a LAN that you want to connect to the Internet, you will need a router to serve as the translator between information on your LAN and the Internet
Routers (continued)
Physical MediaPhysical Media
Physical media provide the connections between network devices that make networking possible
There are four main types of physical media in widespread use today:
– Coaxial Cable– Twisted Pair– Fiber Optic Cable– Wireless Media
Physical media provide the connections between network devices that make networking possible
There are four main types of physical media in widespread use today:
– Coaxial Cable– Twisted Pair– Fiber Optic Cable– Wireless Media
Ethernet
Physical Media :-10 Base5 - Thick Co-axial Cable with Bus Topology
10 Base2 - Thin Co-axial Cable with Bus Topology
10 BaseT - UTP Cat 3/5 with Tree Topology
10 BaseFL - Multimode/Singlemode Fiber with Tree
Topology
Maximum Segment Length 10 Base5 - 500 m with at most 4 repeaters (Use Bridge to extend the network)
10 Base2 - 185 m with at most 4 repeaters (Use Bridge to extend the network)
10 BaseT - 100 m with at most 4 hubs (Use Switch to extend the network)
LAN Technologies
Thick Coaxial CableThick Coaxial CableThick Coaxial CableThick Coaxial Cable
Used in the first Ethernet networksUsed in the first Ethernet networks Type RG-11 / 10Base5 Type RG-11 / 10Base5 Usually orange/blackUsually orange/black Thickness of a small garden hose Thickness of a small garden hose Very expensive and heavy cableVery expensive and heavy cable Two strands along the axisTwo strands along the axis Conductor down the center Conductor down the center Insulator surrounds conductorInsulator surrounds conductor Shielded mesh serves as outsideShielded mesh serves as outside
Used in the first Ethernet networksUsed in the first Ethernet networks Type RG-11 / 10Base5 Type RG-11 / 10Base5 Usually orange/blackUsually orange/black Thickness of a small garden hose Thickness of a small garden hose Very expensive and heavy cableVery expensive and heavy cable Two strands along the axisTwo strands along the axis Conductor down the center Conductor down the center Insulator surrounds conductorInsulator surrounds conductor Shielded mesh serves as outsideShielded mesh serves as outside
Thin Coaxial CableThin Coaxial Cable
Alternative to Thick Ethernet Cable Type RG-58 / 10Base2 / “Cheapnet” Usually black Thickness of a pencil More flexible than thick Ethernet Reduced the cost of the cabling Flexible
Alternative to Thick Ethernet Cable Type RG-58 / 10Base2 / “Cheapnet” Usually black Thickness of a pencil More flexible than thick Ethernet Reduced the cost of the cabling Flexible
Coaxial cable connectors
The most common type of connector used with coaxial cables is the BNC connector
Twisted Pair CableTwisted Pair Cable
Phone Systems Twisted Pair Cable consists of two copper
wires, usually twisted around each other to cancel out any noise in the circuit
Two main type of Twisted Pair Cabling– Shielded Twisted Pair (STP)– Unshielded Twisted Pair (UTP)
Phone Systems Twisted Pair Cable consists of two copper
wires, usually twisted around each other to cancel out any noise in the circuit
Two main type of Twisted Pair Cabling– Shielded Twisted Pair (STP)– Unshielded Twisted Pair (UTP)
Shielded Twisted Pair (STP)
STP is the original media used for token ring networks STP can be used for high-speed networks, such as FDDI or ATM,
where shielding is important.
RJ-45
Unshielded Twisted Pair (UTP) UTP 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
UTP (Continued)UTP (Continued)
Most commonly used twisted pair cable Uses common telephone wire UTP was standardized by the IEEE 802.3
committee in October of 1990 UTP for LANs is now classified as:
– Category 3 - used for LANs up to 10 Mbps– Category 4 - used for LANs up to 16 Mbps– Category 5 - used for LANs up to 100 Mbps
Most commonly used twisted pair cable Uses common telephone wire UTP was standardized by the IEEE 802.3
committee in October of 1990 UTP for LANs is now classified as:
– Category 3 - used for LANs up to 10 Mbps– Category 4 - used for LANs up to 16 Mbps– Category 5 - used for LANs up to 100 Mbps
Fiber Optic Cable
Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials
It transmits light rather than electronic signals It is the standard for connecting networks between
buildings, due to its immunity to the effects of moisture and light
Fiber Optic (continued)
Fiber optic cable has the ability to transmit signals over much longer distances than coaxial or twisted pair
It can also carry information at vastly greater speeds Fiber optic cable is more difficult to install than other
cabling
Wireless LANS
– Wireless networks use high frequency radio signals to communicate between the workstations and the fileserver or hubs.
– Disadvantages of wireless networks are: they are expensive (relatively), provide poor security, are susceptible to interference and are slower than cabled networks
top related