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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
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
MultiplexingMultiplexing is the process of collecting the data from multiple application processes of the sender, enveloping that data with headers and sending them as a whole to the intended receiver.In Multiplexing at the Transport Layer, the data is collected from various application processes. These segments contain the source port number, destination port number, header files, and data.These segments are passed to the Network Layer which adds the source and destination IP address to get the datagram.DemultiplexingDelivering the received segments at the receiver side to the correct app layer processes is called demultiplexing.The destination host receives the IP datagrams; each datagram ... Read More
Address Resolution ProtocolAddress Resolution Protocol (ARP) is a communication protocol that works on the TCP/IP Layer 2.ARP helps to get the MAC address of the connected router or gateway from the IP address.ARP is a request-response protocol in which one device sends a request to another device asking for some information, the other device will respond/reply with the required information.ARP packets are encapsulated by a link-layer and are distributed only in a specific network. ARP is said to be a link-layer protocol.How Does ARP Work?Before sending an IP packet, the sender must know the destination MAC address.If the MAC address ... Read More