Explain the networks and what they are
MAC address or Media Access Control is a physical address
which is unique to a particular device. If the computer has a network interface
Card (NIC) then its MAC address is either, hard coded which means the MAC
address is read only, or the MAC address is hard wired this means that the
electronic circuits where hard wired when the NIC was built.
APIPA or Automatic Private IP addressing is a Microsoft
windows facility which acts as a backup if the DHCP server fails. It does this
by allocating an IP address in the private range 169.254.255.254 to a client
machine, which in turn checks that the address is unique using ARP. Finally
when the DHCP server is available again, clients automatically update their IP
Class addressing is a network addressing architecture used
in the Internet from 1981 until 1993 when classless inter- domain routing was
introduced. Class addressing divides the address space for the IPv4 into five
address classes by addressing range. Class A has a leading Bits of 0 and the
size of network number bit field is 8. Class B has a leading bits of 10 and the
size of the network bit field is 16, Class C has leading bits of 110 and the
size of the network number bit field is 24. However Class D is used for
multicast and has a leading bits of 1110 and the network number bit field
cannot be defined. Finally Class E is used for reserved and has a leading bits
of 1111 and like Class D the network number bit field cannot be defined.
Classless addressing removes class boundaries to release
‘wasted’ addresses from the class/network/nodes convention. There are just two
groups of bits, each group has variable lengths. The first group is a network
prefix, this identifies one or more network gateways, but the second group is
A private internet address is assigned by the Network
Information Centre (Inter NIC). It is assigned by the NIC to organisations so
that the y can create their own private network. The device that we have on our
own home network all have private IP addresses. This means that no device
outside the network can directly access any of your devices without a Network
Address Translator. Computers within a private organisations will also have a
private IP address.
Loopback is a special range of IP addresses 127.0.0.0 to
127.255.255.255. It is used for testing communication or transportation. A data
packet is sent using a loopback address and is immediately returned to sender
unchanged. But if it has not been returned then there is a possible issue with
the network card.
TCP ports is where a number is given to the user sessions
and servers applications in an IP network. The number is then allocated by the
internet assigned numbers authority (IANA) and is located in the packets header.
It allow the type of packet to be identified. E.g. Email or voice over (VOIP)
A gateway is an access point or IP router that a networked
device uses to send data or messages to another device on a different network
or the internet. The default gateway means that a particular gateway is used by
the device automatically, unless an application states an alternative gateway.
contrast OSI and TCP/IP networking models.
OSI is a short Open system interconnections model. This
defines a network implement protocols in seven layers. The OSI is a reference
model for how applications can communicate over a network. The purpose of the
OSI 7 layer model is that it guides vendors and developers so that the digital
communication products and software programs they create will interoperate and
facilitate clear comparisons among communications tools. The main function of
an OSI network model is to allow communication between two endpoints in a
telecommunication network and this can be divided into seven different groups. The
seven layers of function are provided by a combination of applications,
operating systems, network card device drivers and networking hardware that
enable a system to put a signal on a network cable or out over Wi-Fi or other
wireless protocol). The seven layers are as follows:
Layer 7: the application layer, this layers purpose is to
identify communication partners, this means the OSI is identifying someone else
to communicate with. Within the seventh layer network capacity is also assessed
this creates a thing to send or an opens a thing that is received.
Layer 6: The presentation layer, this layer is usually part
of an OS and the purpose of this is to convert incoming and outgoing data from
one presentation format to another. An example of this would be turning clear
text into encrypted text then transferring that encrypted text to another user
then they turn the encrypted text back into clear text.
Layer 5: the session layer, this layer has the responsibility
of setting up coordinates and terminates conversations. This means the services
included are authentication and reconnection after an interruption has
occurred. On a TCP a user UDP or User
Datagram Protocol provides these services for most applications.
Layer 4: the transport layer, this layer oversees and
manages the packetization of data and the delivery of the data packets,
including checking for errors within the data packet once it arrives.
Layer 3: The network layer, this layer handles the addressing
and routing of data. So the fourth layer oversees sending data to the correct
destination on outgoing transmissions and receiving incoming transmissions at
the packet level. IP is the network layer for the internet.
Layer 2: The data-link layer, primary job is to provide a
links across the physical network, putting data packets into different network
frames. There are two sub layers within the second layer these are called
logical link control layer and the media access control layer. Ethernet is the
main data link layer in use.
Layer 1: The physical layer, this layer converts the bit
stream through the network at the electrical, optical or radio level. It
provides the hardware means of sending and receiving data on a carrier network.
TCP/IP or Transmission Control Protocol/internet protocol is
used as communication protocols to interconnect network devices on the
internet. TCP/IP can also be used as a communications protocols in a private
network an intranet or an extranet. TCP/IP specifies how data is exchanged over
the internet by providing end-to-end communications that identify how it should
be broken into data packets addressed, transmitted, routed and received at the
destination. TCP/IP requires little central management and it is designed to
make networks reliable with the ability to recover automatically from the
failure of any device on the network. IP and TCP are the two main protocols in
the internet protocol suite serve specific functions. The TCP defines how applications
can create channels of communication across a network. TCP is also responsible
for managing how messages are assembled into smaller data packets before they
are transmitted over the internet. The IP is responsible for how to address and
route each data packet to ensure that it reaches the correct destination. Each
gateway computer on the network checks this IP address to determine where to
forward the message.
As you can see from this image the
difference between OSI and TCP/IP is that OSI is separated into sub-layers
rather than being placed in a general layer. The application is split into
three sections on the OSI rather than TCP which just has the one layer doing
all the work. This means that the OSI is much more advanced and intricate, also
with OSI having sub-layers it allows the network protocol run more efficiently
because each layer has a specific set of instructions whereas, TCP/IP have
lesser amount of layers so each layer is doing multiple roles to get the same
result. Because OSI has seven separate layers that have a specific role it
makes designing the layer and debugging of one layer much easier and it does
not disrupt or cause issues to the entire structure.
Within the protocol suite of both
OSI and TCP/IP it shows that OSI uses more protocols than TCP/IP, however they
both use; FTP (file transfer protocol), SMTP (simple mail transfer protocol),
TCP (Transmissions control protocol), IP (Internet Protocol) and UDP (User
diagram protocol) but TCP/IP allows for Ethernet protocol whereas OSI does not.
The Ethernet protocol is the most
widely used network protocol. Ethernet uses an access method called CSMA/CD
(Carrier sense Multiple Access/Collision Detection).
IP or internet protocol is
responsible for the transmission of data packets across a network. The IP
address checks and makes sure that the data being transmitted is sent to the correct
TCP or Transmission control
protocol has the responsibility of checking data that has been sent from the
user’s computer to another computer. If data is lost within the transmission
then the TCP requests that the data is re-sent.
UDP or User datagram protocol is a
transport layer protocol defined for use with the IP network layer
protocol. UDP can be used as an
alternative communications protocol to transmission control protocol (TCP) used
primarily for establishing low latency and loss tolerating connections between
applications on the internet. Both UDP
and TCP run on top of the Internet Protocol (IP) and are sometimes referred to
as UDP/IP or TCP/IP. Both protocols send short packets of data, called
FTP or Tile transfer protocol is a
standard network protocol used to transfer computer files between a client and
server on a computer network. FTP is built onto a client-server model
architecture and uses separate control and data connections between the client
and the server. The FTP protocol relies on two communication channels between
client and server. It requires a command channel for controlling the
conversation and a data channel for transmitting the file data. Clients can
initiate conversations with servers by requesting to download a file. By using
a FTP the client can upload, download, delete and rename, move and copy files
on a server.
SMTP or simple mail transfer protocol is an internet
standard for electronic mail transmission. SMTP is also another form of TCP/IP protocol
and is used when sending and receiving e-mails. However, SMTP is limited in its
ability to queue messages at the receiving end. POP3 or IMAP is normally used
alongside SMTP because these protocols allow the user to save message and
emails to their server’s mail box, this makes it easier for the user as they
can then choose when to download the emails and messages. SMTP is typically
used for sending emails and then POP3 and IMAP is used to receive the emails.