Internet Control Message Protocol (ICMP) works in the network layer of the OSI model and the internet layer of the TCP/IP model. It is used to send control messages to network devices and hosts. Routers and other network devices monitor the operation of the network. When an error occurs, these devices send a message using ICMP. Messages that can be sent include "destination unreachable", "time exceeded", and "echo requests".ICMP is a network layer protocol.ICMP messages are not passed directly to the data link layer. The message is first encapsulated inside the IP datagram before going to the lower layer.Types of ... Read More

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

File Transfer Protocol (FTP) is an application layer protocol that is used to transfer the files between the local devices (PC, smartphone, etc.) to a server. It transfers both text and binary files over the Internet.FTP opens two connections between the computers − one for the commands and replies (control connection) and a second one for data transfers (data connection).FTP is built on a client-server model architecture using the control connection and data connection between the client and server.Control ConnectionA Contol Connectcion is established on Port number 21. It is the primary connection and is used to send commands back ... Read More

User datagram protocol (UDP) is a transport layer protocol. It is a connectionless, unreliable protocol that has no flow-and-error control. UDP uses port numbers to multiply data from the application layer. UDP is a simple protocol, it has less overhead. Suppose a process wants to send a small message, then UDP would require very little interaction between the sender and the receiver as compared to the transmission control protocol (TCP).UDP User Datagram FormatUDP packets user datagram has a fixed size header of 8 bytes.UDP Header − It is an 8-bytes fixed header. The first 8 bytes of a datagram contain ... Read More

Transmission Control Protocol/Internet Protocol (TCP/IP) model is a concise version of the OSI Model. The TCP/IP protocol suite was developed before the OSI model. But the layers in the TCP/IP protocol suite do not exactly match those in the OSI model.TCP/IP ProtocolThe original TCP/IP protocol uses four layers − host-to-network, Internet, Transport, and Application layer.The host-to-network layer is equivalent to the combination of physical and data link layers in the OSI model.The Internet layer in TCP/IP is equivalent to the Network layer of the OSI model. And the Application layer does the job of the Session, Presentation, and Application layers ... 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