Network Topologies, Protocols and Layers Finished Flashcards
What is a node
A device connected to a network
What is a network topology
The arrangement in which all nodes are connected together
What are the common network topologies (2)
Star
Mesh (full or partial)
What is the configuration of a star topology
Al nodes directly connected to a central hub or switch (server is a node)
What model does a star topology typically use
Client-server model
What are the advantages of the star topology (3)
Each node is separately connected, therefore a failure of one node or link does not affect any of the other nodes
New nodes can be added to the network by connecting them to the switch
They tend to have higher performance as a message is passed on to its intended recipient only
What are the disadvantages of the star topology (2)
The whole network fails if the switch fails as no node can communicate
Can be expensive if wired due to the cabling
When are star topologies commonly used (2)
Large organisations
Home networks
What is the central connection for all nodes in a home network
Router/WAP
What is the configuration of a mesh topology
Each node is connected to at least one other node (partial mesh) or all other nodes (full mesh)
Why are wired mesh networks uncommon but wireless mesh networks becoming more popular
Wired mesh networks are expensive but it’s becoming easier to connect nodes wirelessly using radio signals
What are the advantages of using a mesh network (5)
Messages can be received more quickly is the route to the intended recipient is short
Messages should always get through as they have multiple routes on which to travel
Multiple connections mean that no node should be isolated
Multiple connections mean each node can transmit to an receive from more than one node at the same time
New nodes can be added without interruption or interfering with other nodes
What are the disadvantages to using a mesh network (2)
Full mesh networks can be impractical to set up due to the large number of connections required
Many connections require a lot of maintenance
When are mesh topologies often used (4)
Military organisations - to avoid breakdown of communication
Cities - help monitor traffic flow, sewage treatment and street lights
Emergency services - ensure communication is reliable
Utility companies - to allow smart meters to send readings automatically
What is ethernet
A protocol that describes how data is transmitted in wired networks
How does a wireless network connect nodes
Wi-Fi
What radio frequencies does Wi-Fi use (2)
2.4 GHz
5 GHz
How does a node connect to a WAP
By a radio transceiver
How are WAPs connected
By wire or wirelessly to a network switch or wirelessly to other WAPs
What are the advantages to using Wi-Fi as a connection in a network
New nodes can be added easily without interruption to the network
What are the disadvantages of using Wi-Fi as a transmission media(4)
Wi-Fi signals have a limited range (>50 metres)
Wi-Fi signals can suffer from electromagnetic interference from other devices and other Wi-Fi signals and can also be blocked by walls leading to dead spots
Each WAP only has so much bandwidth to share among connected nodes
Wi-Fi signals pose a security threat as they can be intercepted, meaning messages have to be encrypted
Why is Wi-Fi so popular (2)
It is easy to connect a node to a network
It’s wireless so there is a lot of freedom of movement
What is encryption
The process of disguising a message so that it cannot be understood by anyone but its intended recipient
What is an unencrypted message called
Plaintext
What is an encrypted message called
Ciphertext
What is asymmetric encryption
Creating a private key and public key
What is the public key used for
Encrypting the message: anyone can do this
What is the private key used for
Decrypting the message: this is never given out
When is asymmetric encryption used
Banks use it for all messages
What is a protocol
A set of rules that govern communication
What protocols govern addressing
IP (Internet protocol)
MAC (Media access control)
What is IP addressing
Giving a device a unique IP address when it’s connected to a network
What is the format of an IP address
Four sets of three digits separated by dots
What does a node do when it wants to send a message to another node
It uses the recipient node’s address as the destination. A switch on the network knows where the node with this address is and routes the message to it
what are the types of IP address (2)
static and dynamic
what happens to the IP address of a node when it is assigned a static IP address
it keeps the same address
what happens to the IP address of a node that has been assigned a dynamic IP address
it has a different IP address based on the network it joins
what is DHCP
dynamic host configuration protocol
assigning a device a different IP address every time it joins a network
what is the benefit of static addressing
it’s easier for network managers to know which device is on a network
what is the benefit of dynamic addressing
it allows more devices to connect than there are available addresses
what is the difference between IPv4 and IPv6
IPv4 uses four digits to hold the IP address
IPv6 uses six digits to hold the IP address
what is a MAC address
a unique serial number assigned to each network interface controller (NIC) which allows a network to uniquely identify any device even when a dynamic IP address is used, by giving each device a unique MAC address
what is the format of a MAC address
a string of hexadecimal numbers
what is TCP/IP
transmission control protocol/internet protocol
enables communication over the internet
what is HTTP and HTTPS
hypertext transfer protocol (secure)
governs communication between a webserver and a client. HTTPS includes secure encryption to allow transactions to be made over the internet
what is FTP
file transfer protocol
governs the transmission of files across a network and the internet
what is SMTP
simple mail transfer protocol
governs the sending of email over a network to a mail server
what is POP and IMAP
post office protocol and internet message access protocol
governs retrieving emails from email servers. same thing but IMAP is replacing POP
what does network layering mean
breaking up the sending of messages into separate components and activities . can be referred to as TCP/IP
what are the four types of network layers [describe]
application layer - encodes/decodes the message in a form that is understood by the sender and the recipient
transport layer - breaks down the message into packets
network layer - adds the sender’s IP address and the recipient’s IP address
data link layer - enables the transfer of packets between nodes on a network, and between one network and another
what is the benefit of layering
it allows standards to be developed and allows it to be adapted to new hardware and software
what is packet switching
turning messages into small packets
what does a packet consist of (2)
header - includes both IP addresses, packet number, total number of packets and protocols used
payload - actual message
