A firewall is a network security device; it is a protective layer for the server that monitors and filters all the incoming and outgoing network traffic. It uses a set of rules to determine whether to allow or block a specific network traffic. Firewalls can prevent unauthorized use before reaching the servers. Firewalls can be hardware or software-based.Firewall PoliciesTo protect private networks and individual machines, a firewall can be employed to filter incoming or outgoing traffic based on a predefined set of rules known as firewall policies.Packet flowing through a firewall can have one of the following three outcomes −Accepted ... Read More

Circuit Switching is a connection-oriented service that uses a dedicated path from the sender to the receiver. Before sending any data from the source to the destination, it needs to set up an end-to-end path.Circuit switching has the minimum chance of data loss due to the dedicated circuit path, but a lot of bandwidth is wasted as a path cannot be used by other senders during a congestion.Three Phases of Circuit SwitchingFollowing are the three phases of circuit switching −Circuit Establishment − A dedicated circuit is established between the two end-devices or from the source to the destination using the ... Read More

Internet protocol version 6 (IPv6) headers is the next generation of the internet protocol designed to replace the current version, or Internet Protocol Version 4 (IPv4). IPv6 fixes many problems in IPv4, such as the limited number of available IPv4 addresses.IPv6 uses 128-bit addresses; an address space is large enough to last for the predictable future. IPv6 added many improvements to IPv4 in areas such as routing and network auto-configuration.IPv6 is a progressive step from IPv4, some IPv4 functions that do not work were removed from IPv6.IPv6 is an Internet Protocol for packet-switched internetworking; it provides end-to-end datagram transmission across ... Read More

The OSI (Open Systems Interconnection) model is developed by the International Standard Organization. It is a layered framework for the design of network systems that allows communication between all types of computer systems. Its primary purpose is to provide a set of structural guidelines for exchanging information between computers, workstations, and networks.The Seven Layers of OSI ModelLayers No.Layers NameFunctionLayer 1Physical LayerTransmission method used to propagate bits through a networkLayer 2Data Link LayerFrame formatting for transmitting data across a physical communication line.Layer 3Network LayerNetwork addressing and packet transmission on the network.Layer 4Transport LayerData tracking as it moves through a network.Layer 5Session ... Read More

The sliding window protocol is a flow control protocol that allows both link nodes A and B to send and receive data and acknowledgments simultaneously.Here, the sender can send multiple frames without having to wait for acknowledgments.If no new data frames are ready for transmission in a specified time, a separate acknowledgment frame is generated to avoid time-out.Each outbound frame contains a sequence number ranging from 0 to 2𝑛−1(𝑛 bit field). For stop-and-wait sliding window protocol, 𝑛 = 1.Sender WindowSender Window is a set of sequence numbers maintained by the sender corresponding to the frame sequence numbers of frames sent ... Read More

In distance-vector routing (DVR), each router is required to inform the topology changes to its neighboring routers periodically. Historically it is known as the old ARPNET routing algorithm or Bellman-Ford algorithm.How the DVR Protocol WorksIn DVR, each router maintains a routing table. It contains only one entry for each router. It contains two parts − a preferred outgoing line to use for that destination and an estimate of time (delay). Tables are updated by exchanging the information with the neighbor’s nodes.Each router knows the delay in reaching its neighbors (Ex − send echo request).Routers periodically exchange routing tables with each ... Read More

Circuit SwitchingCircuit Switching is a connection-oriented service. It provides a dedicated path from the sender to the receiver. In-circuit switching, a connection setup is required to send and receive data. It has very little chance of data loss and error due to the dedicated circuit, but a lot of bandwidth is wasted because the same path cannot be used by other senders during a congestion. Circuit switching is completely transparent; the sender and receiver can use any bit rate format or framing method.Advantages of Circuit SwitchingIt uses a fixed bandwidth.A dedicated communication channel increases the quality of communication.Data is transmitted ... Read More

Network devices or networking hardware are the physical devices that are used for establishing connections and facilating interaction between different devices in a computer network. Hub Hubs work in the physical layer of the OSI model. A hub is a device for connecting multiple Ethernet devices and making them act as a single network segment. It has multiple inputs and output ports in which a signal introduced at the input of any port appears at the output of every port except the original incoming port. A hub can be used with both digital and analog data. Hubs do not perform ... Read More

Routing is the process of moving the data across a network from a source to a destination. Routing algorithms are used to decide the route or the output line a packet should be transmitted on. Routing algorithms determine the optimal path to reach a destination.A good routing algorithm should process properties such as correctness, simplicity, robustness, stability, fairness, and optimality.Fixed RoutingFixed routing is used to find a single permanent route for each source-to-destination pair. It determines the routes using a least-cost algorithm and the routes are fixed at least until a change occurs in the network topology.Fixed Routing − ExampleCentral ... Read More

Dynamic Host Configuration Protocol (DHCP) is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway. In DHCP, port number 67 is used for the server and 68 is used for the client.DHCP allows a network administrator to supervise and distribute IP addresses from a central point and automatically sends a new Internet Protocol (IP) address when a computer is plugged into a different place in the network.DHCP is an application layer protocol that provides −Subnet MaskRouter AddressIP AddressDHCP Client-Server Communication DiagramIn ... Read More