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Distance Vector Routing Example5/1/2021
Routers with BGP implementation determine the shortest path across a network based on a range of factors other than hops.Please help improve it or discuss these issues on the talk page.Learn how and when to remove these template messages ).Please help to improve this article by introducing more precise citations.
![]() Please help improve it to make it understandable to non-experts, without removing the technical details. November 2013 ) ( Learn how and when to remove this template message ). Distance-vector routing protocols measure the distance by the number of routers a packet has to pass, one router counts as one hop. Some distance-vector protocols also take into account network latency and other factors that influence traffic on a given route. ![]() Distance-vector routing protocols also require that a router informs its neighbours of network topology changes periodically. Another way of calculating the best route across a network is based on link cost, and is implemented through link-state routing protocols. The distance vector algorithm was the original ARPANET routing algorithm and was implemented more widely in local area networks with the Routing Information Protocol (RIP). The best route for Internet Protocol packets that carry data across a data network is measured in terms of the numbers of routers (hops) a packet has to pass to reach its destination network. Additionally some distance-vector protocols take into account other traffic information, such as network latency. To establish the best route, routers regularly exchange information with neighbouring routers, usually their routing table, hop count for a destination network and possibly other traffic related information. Routers that implement distance-vector protocol rely purely on the information provided to them by other routers, and do not assess the network topology. The least cost route between any two nodes is the route with minimum distance. Once a router has this information it is able to amend its own routing table to reflect the changes and then inform its neighbours of the changes. This process has been described as routing by rumour because routers are relying on the information they receive from other routers and cannot determine if the information is actually valid and true. There are a number of features which can be used to help with instability and inaccurate routing information. RIPv1 was formally standardised in 1988. It establishes the shortest path across a network purely on the basis of the hops, that is numbers of routers that need to be passed to reach the destination network. RIP is an interior gateway protocol, so it can be used in local area networks (LANs) on interior or border routers. Routers with RIPv1 implementation exchange their routing tables with neighbouring routers by broadcasting a RIPv1 packet every 30 second into all connected networks. ![]() This hop limit was introduced to avoid routing loops, but also means that networks that are connected through more than 15 routers are unreachable. BGP is an exterior gateway protocol and therefore implemented on border and exterior routers on the Internet. It exchanges information between routers through a Transmission Control Protocol (TCP) session.
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