Network and Security: Layers, Multiplexing, and Error Control Mechanisms

NETWORK AND SECURITY
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Introduction
Network security are the procedures and practices aimed towards the protection of a network and
its data from malicious and unauthorized access. The activities protected against include access to
data, modification of the data and misuse of the data such as deletion of part or whole of the data
and network control mechanisms such as denial of service. Network security involves policies and
practices managed through the responsibility of a network admin. The network access is controlled;
identification procedures are utilized such as log in credentials or a passphrase. The network is
categorized into several layers, application, internet and the physical layer discussed in the text.
Application layer.
The application layer provides the interface from which the users can access the services provided
by the network such as web browsing, email services and social media. The application layer if
formed by platform specific applications that have the ability to establish and utilize connections via
the network, the applications are installed on the devices, phones and computers. There are
different architectures of the application layer:
The server-client architecture: the server authenticates the client and allows the client access
information contained within the server such as storage or computing. The client uses the
application layer to access the server.
Peer-peer architecture: in this model of connection, either device connected can provide
information to the other and therefore act in the capacity of the server or client depending on the
direction of data transfer.
In a more categorical classification, the application layer can be described as host-based or cloud-
based. Web browsers and emails are used to illustrate examples of the application layer.
Internet layer:
In this layer, the address resolution protocol defines the MAC address of the devices that are
connected to the network. In the attempt to illustrate the address resolution protocol, the following
commands are used:
The arp-a is used to view the cache in the address resolution protocol.
Since the ip is the true address of an entry into the network, the command arp-d ip is used to delete
an entry.
The command arp-d* is used to delete all the entries in the address resolution protocol.
Reviewing the data link, the commands were demonstrated on a computer running on the Linux
platform. The network layer is used for the transmission of data and communication between the
devices connected. The ipv4 and ipv6 are used in the network layer.
Physical layer.
The physical layer is the connection in an existing network of the connected devices. The layer is
defined by the Manchester encoding, multiplexing, transmission media and the data flow of Analog
or digital data.