"Optimal routeing in the Internet Computer networking is the most happening area in the so-called digital era that we areliving. Devices and drivers are becoming obsolete in the wink of an eye, and there is everlastingthirst for evolution and keep ourselves updated.Optimisation of the routeing process is one such aspect which can enhance the performanceand reduce the cost of networking, thereby assuring a pleasant experience to its users. Switches androuters are the keys to form a good network. This article explores various aspects about the routeing optimisation.Routeing: A router is a decision-making device/software, as to where the data packets need to beforwarded through various links, towards their destination, based on its routeing table andalgorithms. In addition to selecting an optimal path, a router is also concerned with securelytransmitting the data to its next node.The routeing function is associated with the layer-3 of standard OSI network model and hasample contribution its performance.Some of the performance criteria that need to be optimised are throughput, delay, simplicity,low overhead, reliability/stability, and flexibility.Shortcomings of existing routeing schemes: Current routeing methods such as Dijkstra'sAlgorithm, Distance Vector algorithm, Hierarchical routeing in the IP backbone are not up to themarkin the sense that, many of them use hop-counts and artificial weights given to the links in forderiving the routeing tables. These techniques being artificial in nature hamper the optimisationprocess. Most algorithms suffer from drawbacks such as possible oscillations, computationalcomplexity, and convergence problems and are unable to perform when router malfunctions. On theother hand, studies reveal that some routeing protocols (like BGP: Border Gateway Protocol) areprone to failures in communication links and need several minutes to converge. In general, we model a network as a set of nodes interconnected by links. A node can havemultiple links to one another. The cost factor for any network is determined based on certain factorssuch as bandwidth and power consumption. In 1974, Cantor and Gerla proposed this as a convexoptimisation problem and used separation techniques to overcome them. In 1977, Gallager provedthe necessary and sufficient conditions for having a minimum-delay routeing and introduced adistributed multi-path routeing. None of these methods are used because of their complexity, lowperformance of processors and low link capacity at the time these methods were proposedWays of achieving optimal routeing: The ideas mentioned here are with the assumption that thereader is familiar with some basic routeing algorithms and quantitative descriptions of variousperformance measures. The mathematical descriptions of the algorithms are too detailed to describewithin the scope of this article. However a brief idea is presented.1. HALO: Hop-by-Hop Adaptive Link-State Optimal Routeing [2]: This first link-state, hop-by-hop routeing algorithm which addresses the traffic engineering problem for intra-domain routeingon the Internet. Furthermore, based on feedback information from the link-state updates, theprotocol automatically adjusts to input data traffic. The router split ratio adjusts accordingly.2. Optinets [3]: This architecture takes into consideration all entities involved in network mobilityand attempts to decentralize the mobility management efforts, instead of putting the burden on asingle entity of the architecture. It provides means for all type of mobile network node to transmitdata to corresponding nodes using optimal routes.3. Cut-through routeing [4]: The cut-through routeing deals with the concept of message splitting toa maximum extent. In doing so, a node can convey the part of the data without waiting for the entirepacket to be received. If there is no additional traffic on the path, the delay of packet delay is equalto the sum of propagation delay and time taken for slowest link data transmission, no matter howmany links are present on the path. Thus, delay can be reduced by as much as a factor of n on a pathwith n links.4. Hot potato (deflection) routeing schemes [4]. In limited space networks, it is important to modifythe routeing algorithm to minimise buffer overflow and the attendant loss of packets. The idea hereis for nodes to send their stored packets as soon as possible, transmitting them on idle channel evenif it is not close to destination thus reducing the delay in transmission.5.Optimal trafficking [5].Another way of optimisation can result if the information flow results along the minimum firstderivative length [MFDL] [4]. Thus the currently existing sub-optimal routeing is brought to thenext level by shifting the flow of an MFDL path from other paths for each OD pair, thereby the cost "