The optimality principle in computer networks is stated as follows −ExplanationThe purpose of a routing algorithm at a router is to decide which output line an incoming packet should go. The optimal path from a particular router to another may be the least cost path, the least distance path, the least time path, the least hops path or a combination of any of the above.The optimality principle can be logically proved as follows −If a better route could be found between router J and router K, the path from router I to router K via J would be updated via ... Read More

Adaptive routing algorithms, also known as dynamic routing algorithms, makes routing decisions dynamically while transferring data packets from the source to the destination. These algorithms constructs routing tables depending on the network conditions like network traffic and topology. They try to compute computes the best path, i.e. “least – cost path”, depending upon the hop count, transit time and distance.Types of Adaptive Routing AlgorithmsThe three popular types of adaptive routing algorithms are shown in the following diagram −Centralized algorithm − In centralized routing, one centralized node has the total network information and takes the routing decisions. It finds the least-cost ... Read More

Non-adaptive routing algorithms, also known as static routing algorithms, do not change the selected routing decisions for transferring data packets from the source to the destination. They construct a static routing table in advance to determine the path through which packets are to be sent.The static routing table is constructed based upon the routing information stored in the routers when the network is booted up. Once the static paths are available to all the routers, they transmit the data packets along these paths. The changing network topology and traffic conditions do not affect the routing decisions.Types of Non − adaptive ... Read More

Virtual – circuit and datagram networks are categories of packet switching network. In virtual circuits, a virtual path is established between the source and the destination systems through which the data packets are transferred from the source to the destination. In the other hand, in datagram networks, each data packet called datagram contain adequate header information so that they can be individually routed by all intermediate network switching devices to the destination.DifferencesIssueVirtual – Circuit NetworksDatagram NetworksConnectivityVirtual – circuits are connection oriented networks.Datagram networks are connectionless.PathIn these networks, the path between the source and the destination nodes that is followed by ... Read More

A routing algorithm is a procedure that lays down the route or path to transfer data packets from source to the destination. They help in directing Internet traffic efficiently. After a data packet leaves its source, it can choose among the many different paths to reach its destination. Routing algorithm mathematically computes the best path, i.e. “least – cost path” that the packet can be routed through.Types of Routing AlgorithmsRouting algorithms can be broadly categorized into two types, adaptive and nonadaptive routing algorithms. They can be further categorized as shown in the following diagram −Adaptive Routing AlgorithmsAdaptive routing algorithms, also ... Read More

Multiprotocol Label Switching (MPLS) is a routing technique that augments speed and control of the network traffic by directing data from one node to the next node based on short path labels. Instead of being routed using long network addresses, the data packets are routed through path labels that identify virtual paths between the nodes rather than endpoints. MPLS speeds up traffic flows by avoiding complex lookups in the routing table at each node as in conventional routing algorithms.MPLS is a scalable and protocol-independent routing technique. It works with Internet Protocol (IP), Ethernet, Frame Relay and Asynchronous Transport Mode (ATM). ... Read More

Virtual – circuit network is a category of packet switching network, where a virtual path is established between the source and the destination systems for data communication to occur. This path appears to the user as if it is a dedicated physical path, but actually is a logical circuit allocated from a managed pool of circuit resources as per traffic requirements. The network resources forming parts of this path can be shared by other communications, however, is not visible to this user.Features of Virtual – Circuit NetworkVirtual – circuit switching is done at the network layer of the communication system.In ... Read More

Virtual – circuit network is a category of packet switching network, where a virtual path is established between the source and the destination systems for data communication to occur. This path appears to the user as if it is a dedicated physical path, but actually is a logical circuit allocated from a managed pool of circuit resources as per traffic requirements. The network resources forming parts of this path can be shared by other communications, however, is not visible to this user.Phases of Virtual - Circuit TransmissionThere are three phases of transmission by virtual circuits, set up, data transfer and ... Read More

In a connectionless communication systems, datagram refers to the smallest unit via which data is transmitted. Datagrams are data packets which contain adequate header information so that they can be individually routed by all intermediate network switching devices to the destination. These networks are called datagram networks since communication occurs via datagrams. They exist in packet switching networks.Features of Datagram NetworksDatagram switching is done at the network layer of the communication system.In datagram networks, each data packet or datagram is routed independently from the source to the destination even if they belong to the same message. The network treats the ... Read More

In packet switching networks using datagrams, datagrams are data packets which contain adequate header information so that they can be individually routed by all intermediate switching devices to the destination. These networks are called datagram networks since communication occurs via datagrams.Routing PrincipleIn datagram networks, each data packet is routed independently from the source to the destination even if they belong to the same message. No prior resource or channel allocation is done for the individual packets. As the datagrams are treated as independent units, no dedicated path is fixed for data transfer. Each datagram is routed by the intermediate routers ... Read More