Rapid response method for the failure of links between different routing domains

Abstract

The invention relates to a rapid response method for the failure of a link between two routing domains in a packet-oriented network. Once the failure of a link has been identified, substitute routes are provided for the interrupted routes by the local selection of alternative routes and by the propagation of messages along the substitute routes. In contrast to conventional inter-domain protocols such as the BGP (Iborder gateway protocol) the transmission of messages and the associated modification to the routing only involves routing domains that lie along the replacement routes. In one embodiment, a network-wide propagation of messages takes place if the failure of the link represents a persistent breakdown. As a consequence, optimal routes are re-determined in the entire network. The invention provides breakdown compensation that is appropriate for temporary breakdowns and prevents instabilities that occur as a result of the use of conventional inter-domain protocols.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is the US National Stage of International Application No. PCT / EP2004 / 001171, filed Feb. 9, 2004 and claims the benefit thereof. The International Application claims the benefits of European application No. 03004532.2, filed Feb. 28, 2003, both applications are incorporated by reference herein in their entirety. FIELD OF INVENTION [0002] The invention relates to a rapid response method for the failure of a link between two routing domains in a packet-oriented network. SUMMARY OF THE INVENTION [0003] The invention lies within the field of Internet technologies or, more specifically, in the field of routing methods in packet-oriented networks, and is directed at the transmission of data under real-time conditions. [0004] Currently, by far the most important development in the field of networks is the convergence between voice and data networks. An important future scenario is that data, speech and video data will be transm...

AI Technical Summary

Benefits of technology

[0009] The object of the invention is to specify a method which permits a rapid response to malfunctions during inter-domain routing and, at the same time, avoids the disadvantages of conventional methods.

[0015] The invention has the advantage that it is possible to react rapidly to a malfunction, without it being necessary to effect the propagation of messages throughout the entire network followed by convergence on a new state in terms of the topology. In particular, for malfunctions which are of limited duration, no resource-intensive fault response need take place.

[0018] In a variant, a protocol is specified, to provide for a network-wide propagation of messages for the calculation of optimal routes, for example the BGP protocol. Under this variant, when a link fails the redetermination of optimal routes for the inter-domain routing, to take into account the link failure, is suppressed for a period of time by means of the protocol. In the case of the BGP protocol, for example, the BGP process, on the router to which the link malfunction has been reported, is restrained from sending update messages to other BGP instances. In addition, the router which is neighboring to the link malfunction can act as a proxy for EGP instances which can no longer be reached, and can send keep-alive messages to mimic the orderly functioning of the link which has failed to the BGP processes of other BGP instances. This function, of suppressing messages, can be disabled after the period of time, so that a second propagation of messages takes place for the purpose of determining optimal routes. This development has the advantage that it is possible to distinguish between short-term and longer lasting (“persistent”) malfunctions, whereby the response to short-term malfunctions is the provision of substitute routes and for longer-term malfunctions an appropriate modification of the topology within the overall network is initiated.

[0019] For the handling of short-term malfunctions, it is helpful in addition to identify the route which is replaced by the substitute route, in such a way that it is ready for use again when a message is received about the restoration of the link.

Problems solved by technology

Inter-domain routing is made more complicated by the fact, on the one hand, that the paths determined through the various domains to the destination should be the most optimal possible, but on the other hand the domain operators can use local strategies, which makes it more difficult to calculate paths which are globally optimal, according to objective criteria.

However, this strategy is not in general known to all the network operators with domains through which the traffic is routed, i.e. a network operator must make a local decision about the domain to which he forwards traffic, without full information being available about the optimal path as determined by some metric.

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