A highly reliable network which can restore itself from network failures is one important concept for the future high capacity broadband network. In such self-healing network, flooding based failure-restoration algorithm is used to locate new routes and then to reroute failure traffic to that routes automatically when network failures such as link or node failures occur. Since the speed of this algorithm is degraded by the large amount of restoration messages produced by the process, such large volume messages should be reduced. In this paper, the scheme will be proposed, which reduces the large volume messages and efficiently selects alternative routes. In this scheme, the Message Wall will be used to filter useless restoration messages at the tandem nodes and Multi-Message Selecting method will be used to rapidly select a group of link-disjointed alternative routes from the feasible ones in each Flooding Wave sequence. The simulation results show that restoration messages are dramatically reduced and adequate alternative routes can be quickly found out.

Network survivability against various unexpected failures is one of indispensable technologies for the B-ISDN infrastructure. Self-healing algorithm is the technique to automatically restore the failed VP's (virtual paths) in the backbone ATM network. Since the B-ISDN transports various kinds of traffic with various levels of priority (Grade of Service: GoS), the effective self-healing algorithm should orderly restore the failed VP's based on the priority of their traversing traffic. This paper proposes the priority based restoring self-healing algorithm, which realizes the priority based restoring function by the two-timer mechanisms and a simple capacity reserving protocol. The simulation results show that the proposed algorithm can schedule the restoration process so that the failed VP's with higher priority are restored before the others with lower priority. In addition, the significant improvement in restoration speed for the highest priority traffic class has been achieved.

The self-healing capability against network failure is one of indispensable features for the B-ISDN infrastructure. One problem in realizing such self-healing backbone network is the inefficient utilization of the large spare capacity designed for the failure-restoration purpose since it will be used only in the failure time that does not occur frequently. "Pool-capacity" is the concept that allows some VPs (virtual paths) to efficiently utilize this spare capacity part. Although the total capacity can be saved by using the "Pool Capacity," it is paid by less reliability of VPs caused by the emerging influence of indirect-failure. Thus, this influence of indirect-failure has to be considered in the capacity designing process so that network-designers can trade off the saving of capacity with the reliability level of VPs in their self-healing networks. In this paper, Damage Rate:DR which is the index to indicate the level of the influence caused by indirect-failure is defined and the pool-capacity design scheme with DR consideration is proposed. By the proposed scheme, the self-healing network with different cost (pool-capacity) can be designed according to the reliability level of VPs.

Overlay networks which are dynamically created over underlying IP networks are becoming widely used for delivering multimedia contents since they can provide several additional user-definable services. Multiple overlay paths between a source-destination overlay node pair are designed to improve service robustness against failures and bandwidth fluctuation of the underlying networks. Multimedia traffic can be distributed over those multiple paths in order to maximize paths' utilization and to increase application throughputs. Most of flow-based routing algorithms consider only common metrics such as paths' bandwidth or delay, which may be effective for data applications but not for real-time applications such as Voice over IP (VoIP), in which different levels of such performance metrics may give the same level of the performance experienced by end users. This paper focuses on such VoIP overlay networks and proposes a novel alternative path based flow routing algorithm using an application-specific traffic metric, i.e. "VoIP Path Capacity (VPCap)," to calculate the maximum number of QoS satisfied VoIP flows which may be distributed over each available overlay path at a moment. The simulation results proved that more QoS-satisfied VoIP sessions can be established over the same multiple overlay paths, comparing to traditional approaches.