Unit 4:Local area networks Flashcards
1
Q
purpose of a network
A
to share hardware and software resources
2
Q
LAN
A
networking capabilities of a group of computers which are found near each other.
3
Q
network hardware includes
A
nodes
NIC
connecting devices
4
Q
bounded connection media
A
cables are known as bounded media. Carry signals between computers and peripheral devices in networks
5
Q
bounded medium
A
signals are confined to the medium and do not leave it.
6
Q
examples of bounded media
A
twisted pair
fiber optic cable
7
Q
twisted-pair cable
A
consists of 2 insulated strands of copper wire twisted around each other.
8
Q
name the 2 types twisted-pair cables
A
=shielded twisted pair
=unshielded twisted pair.
9
Q
unshielded twisted pair cable
A
easy to install, expand and troubleshoot.
10
Q
advantages of twisted pair
A
=the cost of the cabling is low
=it is easy to install with simple computer connections
11
Q
disadvantages of twisted pair
A
=the length of the cable cannot be greater than 100m
=Copper cables have inherent weaknesses.
12
Q
weaknesses of copper cables
A
=eavesdropping
=attenuation
=crosstalk
=electro-magnetic interference
13
Q
fiber optic cable
A
optical fibers carry digital data signals in the form of pulses of light. No electric impulses are carried over the fiber-optic cable. This means that fiber optic cannot be tapped, and its data cannot be stolen.
14
Q
fibre optic can send signal in Single mode or multimode
A
true
15
Q
multimode
A
has a larger core core and is typically used for for shorter distances.
16
Q
advantages pf fiber optic cables
A
=data can be transmitted at very high speeds
=data can be transmitted over long distances securely.
17
Q
disadvantages of fiber optic cables
A
=they are more expensive than UTP
=You need the expertise available to properly install and connect to devices.
18
Q
unbounded media
A
connect the source and destination devices without any physical connection.
19
Q
examples of unbounded media
A
=Bluetooth
=microwave and radio radio waves
20
Q
wireless technology
A
allow the transfer of data over both short or long distances
21
Q
wireless communication consists of the following:
A
=radio communication
=microwave communication
=light, visible and infrared such as remote controls
22
Q
Bluetooth
A
the standard for sending data over short distances, using short-wavelength radio transmissions from 2400-2480 MHz signals are sent from fixed and mobile devices, creating Personal Area Networks with high levels of security.
23
Q
Bluetooth:
A
=wireless, inexpensive and automatic
24
Q
advantage of Bluetooth
A
can be both data and voice transmissions a the same time.
25
near field communication
provides a wireless connection between 2 devices within close proximity. Allows for 2-way communication
26
radio waves
type of electromagnetic wave which is known fr their use in communication technologies and data transfer
27
examples of radio waves
radio
television
mobile phones
28
radio waves on the spectrum
ranging from 1mm to more than 100 kilometers
29
name 2 types of transmission technologies
point to point connection directly connects 2 nodes of a network.
broadcast is a communication channel that is shared by all the devices in the network.
30
topology
refers to the physical setup of a network-the way in which the network devices are connected
31
common topologies
star
bus
ring
hybrid technologies
32
Star topology
the cable that is connected to the NIC in each computer and has its other end in a port on a central device called a switch
33
advantages of star topology
=easy to setup and maintain
= problem with one computer or cable will not affect the network
=adding and removing nodes does not upset the network.
=it is easy to extend
=it is the most common topology
34
disadvantages of star topology
=a large amount of cabling is required to connect each node independently to the switch
=the switch adds to the cost
=if the switch fails, the whole system fails
35
Bus topology
all nodes connect to a single cable which has a terminator at each end to stop the signals bouncing out
36
Advantages of Bus topology
=requires less cable than star topology ,cost reduction
=no switch is needed wich also reduce costs
=easy to extend the network
37
disadvantage of bus topology
Faults are difficult to trace because all nodes share the common cable
=the fault in the main cable can shut down the whole network
=can get congested because all signals from all nodes share the common cable.
38
tree topology
what is used these days to connect LANs .A combination of bus and star topology
39
ring topology
all the nodes are connect to each other in a closed loop which is often drawn as a ring .The data signals travel around the loop in one direction .The data signals travel around the loop in one direction passing through all the computers.
40
token ring topology
using the UTP cabling to transmit electric signals
41
FDDI
fiber distributed data interface uses light instead of electric signals to transmit over two fiber optic cable ring.
42
advantages of ring topology
=very orderly network ;every device ha the opportunity to transmit
=each node duplicates the data signals so that very little signal degradation occurs
=can easily create a larder ring network than other types because of the signal boosting and fiber optic cable which is often used for the rings
43
disadvantages of ring topology
=oe malfunctioning workstation can create problems for the entire ntwork because signals must pass through every device
=moves, additions an changes of device can disrupt the network
=the network devices tend to be more expensive
=slower than a star topology under normal load.
44
Hybrid topology
a combination of two or more different network topologies
45
Advantages of a hybrid topology
=reliable as error detecting and troubleshooting is easy
=effective as combinations of topologies can be adapted to suit building layouts and equipment available
=scalable as size can be increased easily.
=flexible, it can be setup to suit the needs of the organization
46
disadvantages of a hybrid topology
=complex in design
| =costly
47
IP address
is a numerical label assigned to each device connected to a computer network so that the device can communicate on the internet. IP addressing is different to Ethernet in that the function of IP address is to access the internet and is used to communicate between devices on a LAN.
48
IPv4
used 32 bit binary bits to crate a single unique address on the network. It is expressed by 4 numbers separated by dots
49
IPv6
uses 128 bits to create a single unique address on the network. It is expressed by eight groups of hexadecimal numbers separated by colons
50
Mac address
Media access control address is a hardware identification number that uniquely identifies each device on a network. It is built into ever network card such as an ethernet card or WIFI card. It cannot be changed.
51
internet protocols
define how data is transmitted between computing devices and over networks. They determine how errors will be controlled and reported on, they also stipulate how data will be compressed or if and data compression will be used .It also determines how the sending device will indicate that I has finished sending and how the receiving device will communicate that it has received the message
52
ARP
address resolution protocol is stored in the RAM of the NIC. The ARP table stores the mac address f all other devices on the network so that when it receives data it knows which device sent the data
53
there are 2 types of IP addresses
:the static and dynamic
54
Static IP address
the computer or devices manually configured to use a certain IP address and this address is unlikely to change
55
Dynamic IP adress
users whose device IP addressees can change over time ,a dynamic address is used.
56
DHCP
Dynamic Hos Configuration Protocol takes all the manual work out of IP addressing normally. When DHCP is enables ,a new device connected to the network asks the DCHP server for an address ,and the server assign one from its pool of unused addresses, The server itself tracks which addresses are used and which addresses are available and keeps a record of which addresses have been assigned to the various devices .However it also means that if a device goes offline ,when it reconnects it may not have the same IP address it had before
57
DNS
are the internet's equivalent of a phone book. They maintain a directory of domain names and translates them to IP addresses
when you type in a web address ,your internet service provider views the DNS associated with the domain name, translates it to a machine friendly IP address and directs your internet connection to the correct website.
58
name the 4 internet protocols
ARP -address resolution protocol
DHCP-Dynamic host configuration protocol
DNS-Domain name server
TCP/IP protocol
59
TCP/IP protocols
is the communication protocol for the internet ,it defines the rules computers must follow in order to communicate with each other over the internet. It defines how data should be formatted ,addressed ,transmitted, routed, and received at its destination over the network.
60
UDP and TCP
like the Transmission control protocol ,the User Datagram Protocol is a transportation protocol that is one of the most important protocols of the internet protocols.
61
Compare UDP and TCP
UDP
=connectionless protocol. When sending data or a message, you are not certain that it will get there. If there is a disruption to the signal there may be corruption while transferring the message
=if you send 2 messages, there are no guarantees on the order you will receive them in
=eg. streaming media applications such as IPTV or movies ,voice over IP and online multiplayer games etc..
TCP
=is connection orientated protocol. If the connection is lost while sending a file or message ,the server will request the lost part. So there is no corruptor while transferring a message.
=If 2 messages are sent along a connection ,one after the other, the messages will be delivered in the correct order
=eg. world wide web, email, file transfer
62
Bounded vs unbounded media
```
WIFI
=slow data transfer speed
=suffers form signal interference due to many environmental factors
=data flow needs to be encrypted
=higher latency
=easy to install and deploy
```
```
Ethernet
=faster data transfer speed
=delivers at a consistent speed
=no need to be encrypted
=lower latency
=cable installation infrastructure is required.
```
63
Advantages of Mesh topology
- reduced cable cost
- it is robust
- easy to extend
64
Disadvantages of Mesh topology
=increased workload for each node
| =initial setup is complicated
65
Wireless Mesh Network(WMN)
comprises many wireless nodes with access points that are spread out among dozens or even hundreds wireless mesh nodes that "talk" to each other and common WIFI standards to communicate to the network using mobile devices.
66
WIFI router
allows multiple computers to join the same network and provides access to the internet. It can function as a switch and as an internet router and access pint .Multiple users can enjoy simultaneous access to the internet using cabled o wireless devices. WIFI routers often include ports and act as a switch
67
Wireless bridge
a component that offers an easy way to link network segments without using cable. It provides a wireless bridge connecting 2 LANs.
68
Hotspots
a site that offers internet access over a wireless local area network with the use of a router or wireless access point connected to a link to an ISP. Hotspots typically use WIFI technology
69
Wireless access point
consists of a fixed point wireless transceiver that broadcasts signal within an area called a microcell. Transceiver is usually called a base station or an access point .Each access point connects to a wired backbone so that users can communicate with users in other microcells or connect with internet connections, and other wired network services . Provide wireless access to a wired ethernet network. Enables you to connect to wired network wirelessly.
70
NIC
acts as as the physical interface or connection between the computer and the network cable. In older computers, the cards were installed in an expansion slot.
71
Repeater
is used to connect network segments over longer distances because the signal strength weakens and must be boosted.
72
Bridge
connects network segments, strengthens the signals as they pass through it and looks at the MAC addresses of the signals ,only forwarding data packets to a different network segment in the MAC address is not in the segment from which the packet comes. Can be used to separate different LANs
73
Bridging table
is used to keep track of the devices on each segment
74
wireless bridges
used to connect network segments in different builds which can be cheaper than using fiber optic cable
75
switch
connects nodes in a star topology .Each computer has a NIC with a cable connected to the RJ45 port on it. A message is sent to the switch in the form of a frame. A switch reduces network traffic by not broadcasting the frame to all connected devices. The frame is sent to the device with the matching MAC address.
76
Router
a sophisticated device that is usually used to connect different networks that use the same protocols .A router boosts signals and uses nodes' IP addresses to determine the best path for data packets to travel along to reach their destinations.
77
routing table
stores information about all networks to which the router is connected. The table is used by the router to determine the best route to be used.
78
OSI model
a model that describes network protocol design and communication. It is divided into 7 layers which network transmissions pass
79
name the 7 layers of the OSI model
```
application
presentation
session
transport
network
data link
physical
```
80
application, presentation and session layers
=app layer will send the data to the presentation layer and the presentation layer translates the data into binary and compresses it .
=when you send message, the presentation layer encrypt the message.
=when you download files, this session layer determines which data packets belong to which files
=the session layers also establishes ,maintains and ends communication between devices.
81
transport layer
=receives data from layer 5(session) and breaks it into segments
=controls the amount of data transmitted
=perform error checking ,if a segment data is missing the transport layer resends it.
=TCP data quality over speed and UDP is designed for speed over quality
82
network layer
=transmits data segments between networks in the form of packets
=layer assigns source and destination IP address
=layer also determines the best paths for data delivery
=routers
83
datalink layer
=receives packets from the network layer
=performs physical addressing by adding mac addresses to the data packet
=allows the upper network layers to access media
84
physical layer
the things you can physically touch
| =hardware
85
packet
created by layer 3(network) of the network and allow information to be exchanged between different LANs
86
header
contains instructions about the data carried by the packet.
```
include:
packet length
synchronization
packet number
protocol
destination address
source address
```
87
payload
the actual data that the packet is delivering to the destination
88
trailer
contains bits that tell the receiving device that the end of the packter us reached
=error checking
89
trailer
contains bits that tell the receiving device that the end of the packet us reached
=error checking
90
VLAN
a subnetwork which can grouptogether collections of devices in a LAN to create a new virtual LAN
=make it easier to divide LAN into logical LANs which group similar devices based on their function or security requirements
91
VLAN
a subnetwork which can group together collections of devices in a LAN to create a new virtual LAN
=make it easier to divide LAN into logical LANs which group similar devices based on their function or security requirements
=help improve the overall performance of a network.
92
VLAN tag
allow LAN switches to distinguish between physical groups and logical groups of LAN ports.
93
Wireless LAN
=a wireless network interface card with a transceiver is installed in each device
=built for small scale local networking
=provide temporary connections to an existing network ,cabled network
=help provide backup to an existing network
=provide some degree of probability.
=extend networks beyond the limits of cable connectivity.
