Networks Flashcards
What are the two protocols used that connect an IP address to a MAC address?
ARP (Address Resolution Protocol) and NDP (Neighbour Discovery Protocol)
What is a MAC address?
A hardware address that is usually tied to the network interface card (NIC) in a computer (A computer’s address) - 48 bit used by ethernet
The internet
a network of networks on a very large scale
Network
A group of computers connected so they can communicate with each other
Network of networks
Group of networks connected together so they can communicate with one another
Heterogeneous networks
Different types of network (i.e. ethernet and ATM, can work together)
Protocol
Describes how communication should happen
IP address
Networks are given an address (just like how computers are given a MAC address). IP addresses allow you to identify which networks an address is in.
IP address classes
Class A - 16.7m address per network
128.0.x.x to 191.255.x.x
Class B - 65536 addresses per network
128.0.x.x to 191.255.x.x
Class C - 256 addresses per network 1
92.0.0.x to 223.255.255.x
Class D - used for multicast
224.0.0.0 to 239.255.255.255
Class E - reserved
240.0.0.0 to 255.255.255.255
Classless inter-domain routing
Aimed to slow the rapid growth of routing tables and slow IP address space
Allows a variable number of bits to be used to identify the network
Generally written as an IP address followed by the number of bits that represent the network
IPv6
IPv4 address space was quickly used up
IPv6 was developed in the 90s to combat this
Uses 128 bits to represent the address - this is a huge number
Addresses usually written in hexadecimal notation
More on IP addresses
Network part allocated by a standards body
Within the network, you are free to divide it up as you wish
May have smaller networks internally
Address configurations can be:
configurable - you specify the IP address (called a static IP address)
Dynamic - Computer automatically allocates an address
circuit switch
a ‘circuit’ formed between two machines to allow communication
packet switch
network connection broken up into smaller packets, sent interleaved with other network packets down a single set
advantages of packet switching
better network utilisation due to smaller packets, less bandwidth is used
When not being sent, other computers can use the same connections to send data between them
Most networks are packet switched now
bandwidth
the capacity to carry data
Disadvantages of packet switching
You are not guaranteed that the packets will arrive in the same order that you send them.
You are not guaranteed that all packets will even arrive unlike a circuit switch
OSI network layer model
Provides seven layers of protocols that provide increasingly higher level of abstraction of how networks work
7 - application 6 - Presentation 5 - Session 4 - Transport 3 - Network 2 - Data Link 1 - Physical
OSI - Physical
How the data goes over ‘the wire’, although might not be a wire e.g. fibre optic
Describes how bits get converted into electrical signals and sent
OSI - Data link
How the data is formatted on the wire
Packets sent out as frames
Give details of the packet (e.g. size, who it’s for)
OSI - Network
Enable packet forwarding between networks
Connectionless - the unit of transmission is a packet, have no idea that the packet sent contains information from the previously sent
OSI - Transport
End to end communication - send data, arrives, handles errors
Ensures reliability
OSI - Session
Managing a session between end use applications processes
Not really used in TCP/IP
OSI - Presentation
How data is presented to the application e.g. HTML, CSS
OSI - Application
The user interface in the OSI model
In TCP/IP , the protocols used between applications
E.g. HTTP, POP3, IMAP
Address resolution Protocol (ARP)
Used to translate the IP address of the host or computer connected to a network to a MAC address on IPv4 networks
Neighbour Discovery Protocol (NDP)
Used to translate the IP address of the host or computer connected to a network to a MAC address on IPv6 networks
Domain Name System (DNS)
Used to convert IP addresses to humanely readable names
Distributed hierarchal system that can map names to IP (and other things)
