Unit 4 includes:
PACKETS
PROTOCOLS
IP TCP HTTP FTP PROTOCOL STACKS
3 NETWORK TYPOLOGIES:
STAR
BUS
RING
LAN
WAN
STAND ALONE COMPUTERS
NETWORK SECURITY:
USER ACCESS LEVELS
SUITABLE PASSWORDS
ENCRYPTION TECHNIQUES
NETWORK POLICIES;
ACCEPTABLE USE
DISASTER RECOVERY
BACKUP
ARCHIVING
PACKETS
PROTOCOLS
IP TCP HTTP FTP PROTOCOL STACKS
3 NETWORK TYPOLOGIES:
STAR
BUS
RING
LAN
WAN
STAND ALONE COMPUTERS
NETWORK SECURITY:
USER ACCESS LEVELS
SUITABLE PASSWORDS
ENCRYPTION TECHNIQUES
NETWORK POLICIES;
ACCEPTABLE USE
DISASTER RECOVERY
BACKUP
ARCHIVING
Packets
small piece of a file (which is more secure to break up into to pieces)
contains:
starting address
delivery address
packet number
how many packets
data its holding
Protocols
set of rules that determine (control) how data is transmitted across a network
contains:
how to stop and start a connection
how to stop and start a message
how to deal with corrupted data
how to format the data
protocol stack=several layers of protocols that work together
IP=Internet Protocol
TCP=transmission control protocol
HTTP=hypertext transfer protocol
FTP=file transfer protocol
SMTP =simple mail transfer protocol
Bus Network
all the workstations servers and printed are connected to one main cable and at each end of the cable there is a terminator that soaks up loose/extra information so that it wont reflect back down the bus.
small piece of a file (which is more secure to break up into to pieces)
contains:
starting address
delivery address
packet number
how many packets
data its holding
Protocols
set of rules that determine (control) how data is transmitted across a network
contains:
how to stop and start a connection
how to stop and start a message
how to deal with corrupted data
how to format the data
protocol stack=several layers of protocols that work together
IP=Internet Protocol
TCP=transmission control protocol
HTTP=hypertext transfer protocol
FTP=file transfer protocol
SMTP =simple mail transfer protocol
Bus Network
all the workstations servers and printed are connected to one main cable and at each end of the cable there is a terminator that soaks up loose/extra information so that it wont reflect back down the bus.
Advantages
-easy to install
-cheap (not much cabling)
Disadvantages
-if main cable fails or gets damaged, the whole network will fail
-more workstations means the performance of the network will be slower because of data collisions
-every workstation on the network 'sees' all of the data on the network-security risk
Ring
each device (eg workstation, server, printer) is connected in a ring so each one is connected to two other devices. Each data packet travels in one direction. Each device receives each packet until it gets to its destination device.
-easy to install
-cheap (not much cabling)
Disadvantages
-if main cable fails or gets damaged, the whole network will fail
-more workstations means the performance of the network will be slower because of data collisions
-every workstation on the network 'sees' all of the data on the network-security risk
Ring
each device (eg workstation, server, printer) is connected in a ring so each one is connected to two other devices. Each data packet travels in one direction. Each device receives each packet until it gets to its destination device.
Advantages
-transfers data quickly (as data only flows in one direction so there won't be any data collisions)
Disadvantages
-if the main cable fails or any device is faulty, then the whole network will fail
-transfers data quickly (as data only flows in one direction so there won't be any data collisions)
Disadvantages
-if the main cable fails or any device is faulty, then the whole network will fail
Star Network
Each device on the network has its own cable that connects to a switch or hub. May find in a small network of five or six computers where speed is a priority.
Each device on the network has its own cable that connects to a switch or hub. May find in a small network of five or six computers where speed is a priority.
Advantages
-very reliable (if one cable or device fails, then all the others will continue to work)
-high performing (no data collisions)
Disadvantages
-expensive to install (most cables, and network cable is expensive)
-extra hardware is required (hubs or switches - which add to the cost)
-if a hub or switch fails, all the devices connected to it will have no network connection
-very reliable (if one cable or device fails, then all the others will continue to work)
-high performing (no data collisions)
Disadvantages
-expensive to install (most cables, and network cable is expensive)
-extra hardware is required (hubs or switches - which add to the cost)
-if a hub or switch fails, all the devices connected to it will have no network connection
LAN (Local Area Network)
Network of computers within the same building, such as a school, home or business. A LAN is not necessarily connected to the internet. (Ring Network)
Network of computers within the same building, such as a school, home or business. A LAN is not necessarily connected to the internet. (Ring Network)
WAN (Wide Area Network)
-WANs are formed when LANs are connected. This requires media such as broadband cables, and can connect up organisations based in different geographical places (e.g. WAN may cover a number of offices in a business, like an estate agent with branches in a number of towns).
-WAN is also the internet by connecting a single home computer to the internet
-WANs are formed when LANs are connected. This requires media such as broadband cables, and can connect up organisations based in different geographical places (e.g. WAN may cover a number of offices in a business, like an estate agent with branches in a number of towns).
-WAN is also the internet by connecting a single home computer to the internet
Stand Alone Computers
To connect a stand alone computer (a PC) to a network, you need;
-NIC (Network Interface Card) = a small circuit boards that connect to the motherboard-to connect to network
To connect a stand alone computer (a PC) to a network, you need;
-NIC (Network Interface Card) = a small circuit boards that connect to the motherboard-to connect to network
-MAC Address = unique to every piece of hardware on a network, built into the NIC to identify it and also the maker of it (cant change it)
Network Security
-User Access Level- used for privacy/level of security (e.g. in a large company or school many people will use computers on the same network. a network manager will normally control the level of access people have to the network. general users will not have the ability to download any software or make any changes to the system. The more people have access to sensitive parts of the network, the more likely it is that a hacker or a virus might be able to cause damage.
-Suitable Passwords- mix of upper and lower case letters (at least 7 letters), numbers and special characters (at least 1 symbol)
-Encryption Techniques-method of changing the original numbers and characters so that they are hidden or disguised. (e.g. Caesar Cipher algorithm where each letter of the alphabet is simply replaced by another letter in the alphabet that might be one or more letter positions away OR How the prefix for some web addresses is https instead of http. The ‘s’ indicates that it is a secure website and any payment or personal details that are inputted into the site will be encrypted.
Network Policies
-Acceptable Use- states how the network may be used with rules and guidelines for the users-what is and isn't acceptable (e.g. at work and school, not allowed on social websites or adult websites)
-Disaster Recovery- getting back to normal after a large-scale system failure, most organisations have a system recovery plan. (e.g. most common disaster is loss of electricity-power cut- and in this case they can use a diesel generator or battery powered UPS tp keep the main parts of the system running)
-Backup-another solution to a disaster, backing up data as a secondary storage for it (so using secondary storage devices)
Network Security
-User Access Level- used for privacy/level of security (e.g. in a large company or school many people will use computers on the same network. a network manager will normally control the level of access people have to the network. general users will not have the ability to download any software or make any changes to the system. The more people have access to sensitive parts of the network, the more likely it is that a hacker or a virus might be able to cause damage.
-Suitable Passwords- mix of upper and lower case letters (at least 7 letters), numbers and special characters (at least 1 symbol)
-Encryption Techniques-method of changing the original numbers and characters so that they are hidden or disguised. (e.g. Caesar Cipher algorithm where each letter of the alphabet is simply replaced by another letter in the alphabet that might be one or more letter positions away OR How the prefix for some web addresses is https instead of http. The ‘s’ indicates that it is a secure website and any payment or personal details that are inputted into the site will be encrypted.
Network Policies
-Acceptable Use- states how the network may be used with rules and guidelines for the users-what is and isn't acceptable (e.g. at work and school, not allowed on social websites or adult websites)
-Disaster Recovery- getting back to normal after a large-scale system failure, most organisations have a system recovery plan. (e.g. most common disaster is loss of electricity-power cut- and in this case they can use a diesel generator or battery powered UPS tp keep the main parts of the system running)
-Backup-another solution to a disaster, backing up data as a secondary storage for it (so using secondary storage devices)
-Archiving- compressing files so they are a smaller size and are stored somewhere else safely until they are needed, so that it doesn't take up a lot of space (e.g. accountant)