1. 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

2. 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

3. Workstations
All computers connected to the file server on a network are called workstations

4. 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

5. Ethernet cards
The most common Network Interface Cards are Ethernet cards
They contain connections for either coaxial or twisted pair cables, or both
Co-axial cable
Twisted pair cable

6. 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

7. 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.

8. 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

9. 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

10. Bridges
A bridge is a device that allows you to segment a large network into two smaller, more efficient networks

11. An example of a network with a bridge
Router
Hub
Bridge
Segment
Node
Hub
Internet

12. 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

13. Routers (continued)

14. Physical 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

15. Ethernet Physical Media :- Maximum Segment Length LAN Technologies
10 Base Thick Co-axial Cable with Bus Topology
10 Base 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 Base m with at most 4 repeaters (Use Bridge to extend the network)
10 Base m with at most 4 repeaters (Use Bridge to extend the network)
10 BaseT m with at most 4 hubs (Use Switch to extend the network)

16. Thick Coaxial Cable Used in the first Ethernet networks
Type RG-11 / 10Base5
Usually orange/black
Thickness of a small garden hose
Very expensive and heavy cable
Two strands along the axis
Conductor down the center
Insulator surrounds conductor
Shielded mesh serves as outside
Thick Ethernet cable:
is a specially manufactured cable to be used only in certain Ethernet environments
provides many layers of shielding.

17. Thin 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
Thin Ethernet cable:
was designed in 1984 as an alternative to thick Ethernet cable.
provides a simplification of the Ethernet cabling scheme.
uses a commonly manufactured cable type.
reduces installation time from about 5 minutes to around 1minute.
eliminated or moved certain thick coaxial components which
introduced new connectors

18. Coaxial cable connectors
The most common type of connector used with coaxial cables is the BNC connector

19. Twisted 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)

20. 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

21. 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

22. UTP (Continued) Most commonly used twisted pair cable
Uses common telephone wire
UTP was standardized by the IEEE 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
Unshielded Twisted Pair (UTP) cable:
provides an alternative, easy to use, less expensive cable type for Ethernet networks. .
implements the star topology on Ethernet which allows for better network management
introduced a new component called the concentrator which allows for network cabling to be collapsed into one entity.

23. 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

24. 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

25. 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