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 inform its neighbours of network topology changes periodically.
This process continues until the routing tables of each router converge to stable values.
Additionally, some distance-vector protocols take into account other traffic information, such as network latency.
This hop limit was introduced to avoid routing loops, but also means that networks that are connected through more than 15 routers are unreachable.
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.
It was developed by Cisco in the 1980s and was designed to offer better convergence and cause less network traffic between routers than the link-state routing protocol Open Shortest Path First (OSPF).
The Bellman–Ford algorithm does not prevent routing loops from happening and suffers from the count to infinity problem.
This slowly propagates through the network until it becomes infinity (in which case the algorithm corrects itself, due to the relaxation property of Bellman-Ford).
RIP uses the split horizon with poison reverse technique to reduce the chance of forming loops and uses a maximum number of hops to counter the 'count to infinity' problem.
More recently, a number of loop-free distance vector protocols have been developed — notable examples are EIGRP, DSDV and Babel.
These avoid loop formation in all cases, but suffer from increased complexity, and their deployment has been slowed down by the success of link state routing protocols such as OSPF.