Multi-Domain Resilience: Can I Share Protection Resources with my Competitors?

The Internet consists of a collection of more than 21000 domains called Autonomous Systems (AS) operated mostly under different authorities (operators/providers) that although co-operate over different geographical areas, they compete in a country or other area. Today BGP is the de facto standard for exchanging reachability information over the domain boundaries and for inter-domain routing. The GMPLS controlled optical beared networks are expected to have similar architecture, however, more information has to be carried for TE, resilience and QoS purposes. Therefore, extensions of BGP and of PNNI as well as the PCE have been proposed. Still in all cases emerges the question of protection shareability. For dedicated protection it is enough to know the topology of the network to be able to calculate disjoint paths. However, to be able to perform sharing of protection resources (shared protection) it is not enough to know the topology, but it is mandatory to know exact working and protection path pairs for all the demands, since protection paths can share a certain resource only if there is no such a pair of working paths that contain any element from the same Shared Risk Group (SRG). This can be checked within a domain where the full topology and link-state information is flooded, however, over the domain boundaries for security and scalability reasons no such information is being spread. In this paper we propose using two techniques that do not require flooding the information on working and protection paths while they still allow sharing of resources. These two techniques are the Multi-Domain p- Cycles (MD-PC) and the Multi-Domain Multi-Path Routing with Protection (MD-MPP). After explaining the principles of these methods we give illustrative results.