computer networking A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ma ...

and

telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

, route flapping occurs when a router alternately advertises a destination network via one route then another, or as unavailable and then available again, in quick sequence. Route flapping is caused by pathological conditions (hardware errors, software errors, configuration errors, intermittent errors in communications links, unreliable connections, etc.) within the network which cause certain reachability information to be repeatedly advertised and withdrawn. For example,

link flap Link flap is a condition where a communications link alternates between ''up'' and ''down'' states. Link flap can be caused by end station In networking jargon, a computer, phone, or internet of things device connected to a computer network is ...

occurs when an interface on a router has a hardware failure that causes the router to announce it alternately as "up" and "down". In networks with

link-state routing protocol Link-state routing protocols are one of the two main classes of routing protocols used in packet switching networks for computer communications, the others being distance-vector routing protocols. Examples of link-state routing protocols include ...

s, route flapping will force frequent recalculation of the topology by all participating routers. In networks with

distance-vector routing protocol A distance-vector routing protocol in data networks determines the best route for data packets based on distance. Distance-vector routing protocols measure the distance by the number of routers a packet has to pass; one router counts as one hop. ...

s, route flapping can trigger routing updates with every state change. In both cases, it prevents the network from converging. Route flapping can be contained to a smaller area of the network if

route aggregation A supernetwork, or supernet, is an Internet Protocol (IP) network that is formed by aggregation of multiple networks (or subnets) into a larger network. The new routing prefix for the aggregate network represents the constituent networks in a s ...

is used. As an aggregate route will not be withdrawn as long as at least one of the aggregated subnets is still valid, a flapping route that is part of an aggregate will not disturb the routers that receive the aggregate.

References

{{telecomm-stub

Flapping Flapping or tapping, also known as alveolar flapping, intervocalic flapping, or ''t''-voicing, is a phonological process found in many varieties of English, especially North American, Cardiff, Ulster, Australian and New Zealand English, whereby ...

See also

References