Analysis and algorithms for partial protection in mesh networks

This paper develops a mesh network protection scheme that guarantees a quantifiable minimum grade of service upon a failure within a network. The scheme guarantees that a fraction q of each demand remains after any single link failure. A linear program is developed to find the minimum-cost capacity allocation to meet both demand and protection requirements. For q ≤ 1/2, an exact algorithmic solution for the optimal routing and allocation is developed using multiple shortest paths. For q >; 1/2, a heuristic algorithm based on disjoint path routing is developed that performs, on average, within 1.4% of optimal, and runs four orders of magnitude faster than the minimum-cost solution achieved via the linear program. Moreover, the partial protection strategies developed achieve reductions of up to 82% over traditional full protection schemes.National Science Foundation (U.S.) (NSF grant CNS-0626781)National Science Foundation (U.S.) (NSF grant CNS-0830961)United States. Defense Threat Reduction Agency (grant HDTRA1-07-1-0004)United States. Defense Threat Reduction Agency (grant HDTRA-09-1-005)United States. Air Force (Air Force contract #FA8721-05-C-0002

Network protection with multiple availability guarantees

We develop a novel network protection scheme that provides guarantees on both the fraction of time a flow has full connectivity, as well as a quantifiable minimum grade of service during downtimes. In particular, a flow can be below the full demand for at most a maximum fraction of time; then, it must still support at least a fraction q of the full demand. This is in contrast to current protection schemes that offer either availability-guarantees with no bandwidth guarantees during the downtime, or full protection schemes that offer 100% availability after a single link failure. We develop algorithms that provide multiple availability guarantees and show that significant capacity savings can be achieved as compared to full protection. If a connection is allowed to drop to 50% of its bandwidth for 1 out of every 20 failures, then a 24% reduction in spare capacity can be achieved over traditional full protection schemes. In addition, for the case of q = 0, corresponding to the standard availability constraint, an optimal pseudo-polynomial time algorithm is presented.National Science Foundation (U.S.) (NSF grants CNS-1116209)National Science Foundation (U.S.) (NSF grants CNS-0830961)United States. Defense Threat Reduction Agency (grant HDTRA-09-1-005)United States. Defense Threat Reduction Agency (grant HDTRA1-07-1-0004)United States. Air Force (Air Force contract # FA8721-05-C-0002

Network architectures for supporting survivable WDM rings

Abstract: With WDM, a single physical link failure may correspond to multiple logical link failures. We consider the design of physical topologies that ensure logical rings can be embedded in a survivable manner. ©2002 Optical Society of America OCIS codes: (060.0060) Fiber optics and optical communications; (060.4250) Network

ABSTRACT

The focus of this paper is dynamic resource allocation algorithms for sharing the limited uplink resources of a future satellite system among many bursty users with varying QoS requirements. The data rates provided to each terminal are selected to differentiate between multiple QoS priority levels, provide fairness, and to maximize system capacity under time-varying channel conditions and traffic loads. The proposed resource schedulers are compared to alternative approaches and shown to provide dramatic improvements in both the average data rates and delay characteristics experienced by the users. I

Physical topology design for survivable routing of logical rings in WDM-based networks

In a wavelength-division multiplexed (WDM)-based network, a single physical link failure may correspond to multiple logical link failures. As a result, two-connected logical topologies, such as rings routed on a WDM physical topology, may become disconnected after a single physical link failure. We consider the design of physical topologies that ensure logical rings can be embedded in a survivable manner. This is of particular interest in metropolitan area networks, where logical rings are in practice almost exclusively employed for providing protection against link failures. First, we develop necessary conditions for the physical topology to be able to embed all logical rings in a survivable manner. We then use these conditions to provide tight bounds on the number of physical links that an-node physical topology must have in order to support all logical rings for different sizes. We show that when R the physical topology must have at least R Q links, and that when T the physical topology must have at least Q P links. Subsequently, we generalize this bound for all R. When P, we show that the physical topology must have at least P R links. Finally, we design physical topologies that meet the above bounds for both aRand a P. Specifically, our physical topology for embedding @ PA-node rings has a dual hub structure and is able to embed all rings of size less than I in a survivable manner. We also provide a simple extension to this topology that addresses rings of size a I and rings of size a for odd. We observe that designing the physical topology for supporting all logical rings in a survivable manner does not use significantly more physical links than a design that only supports a small number of logical rings. Hence, our approach of designing physical topologies that can be used to embed all possible ring logical topologies does not lead to a significant overdesign of the physical topology