Network topologies Flashcards
Will Every computer on a network have an IP address?
Yes
How does packet switching operate?
- A file is split into data packets
- Routers follow the IP rules and direct data packets towards their destination.
- Due to network traffic, packet switching may occur where the packets may take different routes and be directed to other routers before arriving at the destination.
- If the packets are in the wrong order, the sequence number can be used to reorder them back into the original file.
What is a protocol and why are they needed?
Protocols are rules that computers follow when transmitting and receiving data over a network.
They are needed to ensure that to ensure computers on a network can understand each others so that
1. data is sent and received correctly
2. data is sent to the correct place
what is SSID?
Stands for “Service Set Identifier.” An SSID is a unique ID that consists of 32charactersand is used for namingwirelessnetworks. When multiple wireless networks overlap in a certain location, SSIDs make sure that data gets sent to the correct destination.
Devices on a wireless network send and receive data using?
standard radio frequency bands
What is the IMAP – Internet Message Access Protocol?
IMAP – Internet Message Access Protocol
This is similar to POP but with one important difference. With IMAP, the email will remain on the server once it has been downloaded by a mail client. This allows other devices to also access the emails which is important for users with multiple devices – they can synchronise their emails across all devices.
What are the features of an Ethernet - STAR topology?
Twisted pair cabling allows duplex transmission (signal can travel in both directions at the same time)
Doesn’t need CSMA/CD protocol
What must happen to data broadcasted on a wireless network?
Data must be encrypted when broadcasted on a wireless network
Devices can communicate with each other when …?
Devices can communicate with each other when
The use the same frequency and channel
What do we call an a 32 bit number written as 4 decimal numbers eg: 129.168.1.101
IP address
what are the features of an Ethernet - BUS topology?
Shared backbone
Used CSMA/CD protocol
Device listens to the line prior to transmission
Stops if it detects a transmission on the line
Repeats the attempt after a random period of time
what are the Advantages
of using wireless networks?
Advantages
Easier to set up so less expensive
Can move around and access the network from anywhere
Can handle large numbers of users
Mesh topology
This is a fully connected network;
Every node is connected to all others;
This means that if a cable breaks or if there is heavy traffic on one area, there are other routes for the data to take
BUT:
It can be a very expensive set up due to the cabling required
What has the following?: 1. Header Destination IP address Source IP address A sequence number 2. The data itself 3. A checksum which is used for error checking
A data packet
partial mesh topology
Some, but not all computers are connected to each other
There are still alternative routes between computers
It is an effective compromise between cabling cost and effective communications
What is a hardware identification number that uniquely identifies each device on a network.
A MAC address
If you have your documents / files stored on a file server, the way you access them will be governed by the xxxx xxxxxxxx xxxxxxxx? This standard (XXX) ensure that all clients (computers) on a network can access files from a server in the same way.
FTP – File Transfer Protocol
Cables (wired)
There are two main types of cable which can transport data between computers.
they are?
Cables (wired)
There are two main types of cable which can transport data between computers.
Ethernet Cables
These are made up of copper wires with the data being transported via electrical signals. Because they carry electrical signals, they can suffer from interference.
Fibre Optic Cables
These are made up of glass fibres with the data being transported via light signals.
Fibre optic cables are more effective…nothing travels faster than the speed of light! They also do not suffer from interference.
They are however more expensive that Ethernet cables.
Devices on a wireless network send and receive data using standard radio frequency bands:
what bands?
Devices on a wireless network send and receive data using standard radio frequency bands:
2.4 GHz Band (frequencies between 2.4GHz & 2.5GHz)
5 GHz Band (frequencies between 5.725GHz & 5.875GHz)
Each band is split into channels that cover smaller frequency ranges, within the band.
The TCP (Transmission Control Protocol) defines the rules for sending data packets on the Internet It ensures that?? (3 Things)
The TCP defines the rules for sending data packets on the Internet
It ensures that
all data is split up into data packets in the same way.
the data packets are put back together when received by the destination device.
any data received is the same as that sent.
What are Ethernet Cables made of?
Ethernet Cables
These are made up of copper wires with the data being transported via electrical signals. Because they carry electrical signals, they can suffer from interference.
what are the Disadvantages
of using wireless networks?
Disadvantages Slower than a wired network Relies on signal strength to WAP Signal can be obstructed Less secure than a wired network
How does the encryption process work?
Encryption process works as follows
data is converted into cipher text prior to transmission using a key created using the SSID and the password
the data is decrypted by the receiver using the same key
What is a hardware identification number that uniquely identifies each device on a network.
MAC address
What is the TCP / IP protocol?
This is probably the most important protocol as it determines how all data is sent over the internet.
It stands for
TCP – Transmission Control Protocol
Does Ethernet STAR topology need CSMA/CD protocol?
no
what is Ethernet?
Ethernet is a standard for network technologies on wired local area networks.
What is the POP – Post Office Protocol?
POP – Post Office Protocol
Post Office Protocol (POP) is a type of computer networking and Internet standard protocol that extracts and retrieves email from a remote mail server.
what is Needed to ensure that data being sent over a network can be sent to the correct node.
IP address
The topology of a network affects?
3 things
The topology of a network affects:
cost,
performance,
ease of set-up.
What is this?
“This is similar to POP but with one important difference. With IMAP, the email will remain on the server once it has been downloaded by a mail client. This allows other devices to also access the emails which is important for users with multiple devices – they can synchronise their emails across all devices.
“?
IMAP – Internet Message Access Protocol
What is the HTTPS – Hyper Text Transfer Protocol (SECURE)?
HTTPS – Hyper Text Transfer Protocol (SECURE)
This protocol is almost identical to HTTP. The only difference is that it ensures all data being sent is encrypted and so makes web data communication far more secure.
Wi-Fi allows network access to portable devices by using what????
Wi-Fi allows network access to portable devices by using radio waves to send data (not wires!).
How is data transmitted over a network?
Data is transmitted in frames/packets
What is SMTP – Simple Mail Transfer Protocol?
SMTP – Simple Mail Transfer Protocol
This protocol governs how data is sent between mail servers. By conforming to the same standards, emails can be sent to and from all mail servers across the internet.
Ethernet
each frame consists of?
5 things
Each frame consists of
Bits to synchronise clocks of transmitting and receiving device
Start frame deliminator to indicate start of the data being sent
Source/ destination MAC addresses
Actual data
Cyclic redundancy check(CRC) for error checking purpose
Data Transfer Media
All networks must enable computers to communicate with one another.
This can be done using two main data transfer mediums.
which are….?
Data Transfer Media
All networks must enable computers to communicate with one another.
This can be done using two main data transfer mediums.
Cables (wired)
Wi-Fi (wireless)
What are Fibre Optic Cables made of?
Fibre Optic Cables
These are made up of glass fibres with the data being transported via light signals.
What is the HTTP – Hyper Text Transfer Protocol?
HTTP – Hyper Text Transfer Protocol
This is the protocol which governs the way in which websites and web servers are accessed by web browsers. By conforming to the same standards it means that all browsers can access all websites on the WWW.
The topology is ….?
Topology is the way in which a network is laid out.
What is The main difference between an IP address and a MAC address?
The main difference between an IP address and a MAC address is that an IP address is not hard coded into the computer. It can change and is therefore said to be dynamic.
What does this describe?
- A file is split into data packets
- Routers follow the IP rules and direct data packets towards their destination.
- Due to network traffic, packet switching may occur where the packets may take different routes and be directed to other routers before arriving at the destination.
- If the packets are in the wrong order, the sequence number can be used to reorder them back into the original file.
Packet Switching
what is the a type of computer networking and Internet standard protocol that extracts and retrieves email from a remote mail server?
POP – Post Office Protocol
What is the protocol which governs the way in which websites and web servers are accessed by web browsers. By conforming to the same standards it means that all browsers can access all websites on the WWW?
HTTP – Hyper Text Transfer Protocol
What does Each data packet consists of?
(3 sections)`
Each data packet consists of 1. Header Destination IP address Source IP address A sequence number 2. The data itself 3. A checksum which is used for error checking
What do we call rules that computers follow when transmitting and receiving data over a network?
protocols
Bus topology
There is only one cable which all nodes are connected to
It is therefore very cheap due to little cabling
But:
Because data travels both ways along one cable, data collides which slows the network
If the cable has a fault the whole network may suffer
Only really useful over small areas
What is th FTP – File Transfer Protocol?
FTP – File Transfer Protocol If you have your documents / files stored on a file server, the way you access them will be governed by the File Transfer Protocol. This standard (FTP) ensure that all clients (computers) on a network can access files from a server in the same way.
What is Packet switching ?
Packet switching ensures that data gets to its destination as fast as possible – this may not be the shortest distance however.
What is the protocol is almost identical to HTTP. The only difference is that it ensures all data being sent is encrypted and so makes web data communication far more secure.
HTTPS – Hyper Text Transfer Protocol (SECURE)
What is manufactured into every network card, such as an Ethernet card or Wi-fi card and therefore cannot be changed (static)?
The MAC address
RIng topology
Again, only one cable
But this time data travels
in only one direction
This means no collisions
BUT:
Again if the cable breaks then the whole network may go down.
WHAT IS A mac ADDRESS?
A MAC address is a hardware identification number that uniquely identifies each device on a network.
The MAC address is manufactured into every network card, such as an Ethernet card or Wi-fi card
and therefore cannot be changed.
What is:
“
This protocol governs how data is sent between mail servers. By conforming to the same standards, emails can be sent to and from all mail servers across the internet.”
SMTP – Simple Mail Transfer Protocol
Star topology
All cables connect to a hub or a switch and therefore data doesn’t share one cable
This results in fewer data collisions and therefore a fast network
BUT – the most expensive topology as it requires the most cable
IP Protocol
why is it in place?
This rule is in place to ensure that data packets are directed towards their destination in the most appropriate way (which may not be the shortest way)
This is called ‘Packet Switching’
Can a MAC address be changed?
No
What are the features of an Ethernet - PARTIAL MESH TOPOLOGY?
Transmitting device checks that line is free and if it is proceeds as follows
1. Data frame is transmitted to a switch
Frame consists of
header which contains MAC source and destination address
data
CRC
2. Switch checks the frame using the CRC and requests retransmission if a problem with the data is identified
3. Switch looks at the address and forwards the frame to the next switch/ destination device
Steps 1-3 are repeated until the frame arrives at its destination. The receiving device will also perform the CRC
Note: frame is directed from source to destination directly via the necessary switches
How are Traditional MAC addresses represented in terms of numbers?
Traditional MAC addresses are 12-digit (6bytesor 48bits) hexadecimal numbers.
why is data encrypted and how does it work?
Data is broadcast on a wireless network so it must be encrypted
Encryption process works as follows
data is converted into cipher text prior to transmission using a key created using the SSID and the password
the data is decrypted by the receiver using the same key
a handshake protocol is used to ensure that the receiver has a valid master key before transmission starts
What is a handshake protocol for?
a handshake protocol is used to ensure that the receiver has a valid master key before transmission starts
