On provision of availability guarantees using shared protection

The Internet has traditionally provided an undefined level of availability based on a best-effort restoration scheme, while the telecommunication networks have provided a somewhat higher level, primarily achieved by dedicated protection. In the coming next generation network, the introduction of new services that have different quality of service (QoS) requirements combined with cost conscious customers who make cost/utility trade-offs, yields a need for the network operators to be able to offer different levels of guaranteed availability. The challenge is to find schemes that can provide the guaranteed availability level requested by each connection while at the same time use bandwidth efficiently. Path protection is a well-known technique to improve the availability of connections in optical networks. When availability guarantees are to be offered, dedicated path protection is easily applicable since the availability of the connections can easily be predicted. Shared path protection, however, is more difficult to apply since the computations usually are more involved. In this paper, two schemes for on-line bandwidth-efficient connection-establishment exploiting shared protection are proposed. The schemes are compared through simulation studies on two realistic network topologies.