Distance-vector routing protocol: Difference between revisions

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== Development of distance-vector routing ==

The oldest [[routing protocol]], and the oldest distance-vector protocol, is version 1 of the [[Routing Information Protocol]] (RIPv1). RIPv1 was formally standardised in 1988.<ref>{{Cite web|url=https://tools.ietf.org/html/rfc1058.html|title=Routing Information Protocol|last=Hedrick|first=C. L.|date=|website=tools.ietf.org|language=en|rfc=1058|archive-url=|archive-date=|access-date=2019-04-16}}</ref> 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 aan [[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 (networking)|broadcasting]] a RIPv1 packet every 30 second into all connected networks. RIPv1 is not suitable for large networks as it limits the number of hops to 15. This hop limit was introduced to avoid routing loops, but also means that networks that are connected through more than 15 routers are unreachable.<ref>{{Cite book|title= Network+ Guide to Networks|author =Tamara Dean |publisher= Cengage Learning|year=2009 |isbn= 9781423902454|pages=274}}</ref>

The distance-vector protocol designed for use in [[wide area network]]s (WANs) is the [[Border Gateway Protocol]] (BGP). BGP is a [[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. Routers with BGP implementation determine the shortest path across a network based on a range of factors other than hops. BGP can also be configured by administrators so that certain routes are preferred or avoided. BGP is used by [[internet service providers]] (ISPs) and telecommunication companies.<ref>{{Cite book|title= Network+ Guide to Networks|author =Tamara Dean |publisher= Cengage Learning|year=2009 |isbn= 9781423902454|pages=274–275}}</ref>