Optimal capacity placement for path restoration in STM or ATM mesh-survivable networks
TL;DR: A method for capacity optimization of path restorable networks which is applicable to both synchronous transfer mode (STM) and asynchronous transfermode (ATM) virtual path (VP)-based restoration and jointly optimizing working path routing and spare capacity placement.
Abstract: The total transmission capacity required by a transport network to satisfy demand and protect it from failures contributes significantly to its cost, especially in long-haul networks. Previously, the spare capacity of a network with a given set of working span sizes has been optimized to facilitate span restoration. Path restorable networks can, however, be even more efficient by defining the restoration problem from an end to end rerouting viewpoint. We provide a method for capacity optimization of path restorable networks which is applicable to both synchronous transfer mode (STM) and asynchronous transfer mode (ATM) virtual path (VP)-based restoration. Lower bounds on spare capacity requirements in span and path restorable networks are first compared, followed by an integer program formulation based on flow constraints which solves the spare and/or working capacity placement problem in either span or path restorable networks. The benefits of path and span restoration, and of jointly optimizing working path routing and spare capacity placement, are then analyzed.
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01 Jan 2006
TL;DR: With the optimization models in this chapter, entire survivable transport networks can be easily designed with essentially the same spare to working capacity (redundancy) ratios as optimized span-restorable mesh networks.
Abstract: p-Cycles are a recently discovered and promising new paradigm for surviv-able networking. p-Cycles simultaneously provide the switching speed and simplicity of rings with the much greater capacity-efficiency and flexibility for reconfiguration of a mesh network. p-Cycles also permit shortest-path routing of working paths (as opposed to ring-constrained working path routing), which adds further to network capacity efficiency. Operationally p-cycles are similar to BLSRs in that, upon failure, switching actions are required at only two nodes and both those nodes are fully pre-planned as to the actions that are required for any failure detected at their sites. With the optimization models in this chapter, entire survivable transport networks can be easily designed with essentially the same spare to working capacity (redundancy) ratios as optimized span-restorable mesh networks. p-Cycles thus bridge the ring versus mesh debate that dominated work in survivable networks through the 1990s and provide the best of both worlds: the efficiency of mesh with the speed of rings.
11 citations
27 Nov 2000
TL;DR: The SANRoP (Simulator for ATM Network Routing Protocols) cell-level discrete event simulator was developed to simulate these protocols in an ATM network in order to determine how well they perform.
Abstract: A high-priority real-time connection is denied admission to an ATM network if insufficient bandwidth is available along all suitable paths through the network. Bandwidth reallocation and dynamic active channel rerouting are techniques that allow a node to select lower-priority channels and reallocate their bandwidth to the new higher-priority connection being admitted. The selected lower-priority channels must then be rerouted through the network so that their QoS requirements can still be satisfied. A local detouring technique, using backup channels, is employed so that reroutes can be handled quickly and efficiently, without violating the QoS requirements of the rerouted channels. Techniques are described which ensure that transmitted data is received on time and in sequence, which is essential for real-time communications. The SANRoP (Simulator for ATM Network Routing Protocols) cell-level discrete event simulator was developed to simulate these protocols in an ATM network in order to determine how well they perform.
10 citations
TL;DR: The problem of reserving the least amount of the network capacity for protection, while guaranteeing fast (local) reroute-based restoration for all the supported connections is shown, it is shown that the problem is NP-complete, and efficient approximation algorithms for the problem are presented.
Abstract: Supporting fast restoration for general mesh topologies with minimal network over-build is a technically challenging problem. Traditionally, ring-based SONET networks have offered close to 50 ms restoration at the cost of requiring 100% over-build. Recently, fast (local) reroute has gained momentum in the context of MPLS networks. Fast reroute, when combined with pre-provisioning of protection capacities and bypass tunnels, enables faster restoration times in mesh networks. Pre-provisioning has the additional advantage of greatly simplifying network routing and signaling. Thus, even for protected connections, online routing can now be oblivious to the offered protection, and may only involve single shortest path computations. In this paper, we are interested in the problem of reserving the least amount of the network capacity for protection, while guaranteeing fast (local) reroute-based restoration for all the supported connections. We show that the problem is NP-complete, and we present efficient approximation algorithms for the problem. The solution output by our algorithms is guaranteed to use at most twice the protection capacity, compared to any optimal solution. These guarantees are provided even when the protection is for multiple link failures. In addition, the total amount of protection capacity reserved by these algorithms is just a small fraction of the amount reserved by existing ring-based schemes (e.g., SONET), especially on dense networks. The presented algorithms are computationally efficient, and can even be implemented on the network elements. Our simulation, on some standard core networks, show that our algorithms work well in practice as well.
10 citations
Cites background from "Optimal capacity placement for path..."
...[11] report that path protection may have as much as 19% less spare protection capacity requirement compared to link protection....
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18 Apr 2005
TL;DR: This work presents several end-to-end protection switching mechanisms for application in multiprotocol label switching (MPLS), and studies the capacity savings of the presented methods for various protection schemes with different traffic matrices.
Abstract: In this work, we present several end-to-end protection switching mechanisms for application in multiprotocol label switching (MPLS). In case of local outages in the network, they deviate the traffic around the failed element over backup paths. They are easy to implement and reduce the additional capacity to maintain the quality of service (QoS) on the backup paths. We study the capacity savings of the presented methods for various protection schemes with different traffic matrices. We further test the influence of different resilience constraints such as the set of protected failure scenarios, bandwidth reuse restrictions due to optical communication, and traffic reduction due to failed border routers.
10 citations
Cites background from "Optimal capacity placement for path..."
...The results of [8] can be well implemented since this work applies only single-paths for both primary and backup paths and relocates only affected primary paths....
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TL;DR: The proposed idle protection capacity reuse (IR) framework generalizes the practice of reutilizing idle spare resources to both failure-free and failure conditions and shows that the utilization of R-IR in dynamic restoration results in an improved low-class lightpath survivability with respect to the utilizationof stub release.
Abstract: Optical networks carrying traffic belonging to different survivability classes must ensure not only the proper survivability differentiation but also the efficient network resource utilization. Current approaches improve network resource utilization by carrying low-class preemptable traffic along high-class spare resources, which are idle (i.e., unutilized) during failure-free conditions. In this paper, the proposed idle protection capacity reuse (IR) framework generalizes the practice of reutilizing idle spare resources to both failure-free and failure conditions. The IR framework is based on the idea of exploiting idle high-class lightpath protection resources not only for routing low-class lightpaths during the provisioning phase (i.e., provisioning-phase IR, P-IR) but also for dynamically restoring low-class lightpaths during the recovery phase (i.e., recovery-phase IR, R-IR). Both P-IR and R-IR have the potential to improve network utilization while providing multiclass lightpaths with the required survivability differentiation. The numerical evaluation shows that the utilization of R-IR in dynamic restoration results in an improved low-class lightpath survivability with respect to the utilization of stub release. Moreover, if P-IR and R-IR are alternatively exploited, then the former improves the provisioning performance, while the latter guarantees a higher survivability. In the end, if P-IR and R-IR are concurrently employed in the provisioning and in the dynamic restoration of two different low classes of lightpaths, respectively, an inherent survivability differentiation is achieved
10 citations
References
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Book•
16 Feb 1970
TL;DR: Interestingly, integer programming and network flows that you really wait for now is coming, it's significant to wait for the representative and beneficial books to read.
Abstract: (1970). Integer Programming and Network Flows. Journal of the Operational Research Society: Vol. 21, No. 4, pp. 500-501.
638 citations
TL;DR: Self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN are proposed and high-speed restoration technique which exploits the benefits of the VP is proposed and described.
Abstract: This paper proposes self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN. First, the characteristics of the virtual paths (VP) and their influence on failure restoration are discussed. A high-speed restoration technique which exploits the benefits of the VP is then proposed and described. The technique simplifies the message transmission processes and reduces the number of generated messages by using preassigned backup virtual paths. Next, the scheme used to design the backup VP routes and spare resource distribution for each link is proposed in order to create a network that applies the proposed restoration scheme. Next, self-reconstruction techniques of backup virtual paths are proposed for the realization of a reversionless restoration cycle. Finally, the feasibility of the distributed control operation is discussed. >
233 citations
TL;DR: A comparative study of the effectiveness of KSP versus Max Flow as an alternative rerouting criteria in the context of transport network span restoration, and the hypothesis is made that a generalized "trap" topology is responsible for all KSP-Max Flow capacity differences.
Abstract: In the development of technologies for span failure restoration, a question arises about the restoration rerouting characteristics to be specified. In theory, maximal rerouting capacity is obtained with a maximum flow (Max Flow) criterion. However, rerouting that realizes the k-successively shortest link disjoint paths (KSP) may be faster, easier, and, in distributed implementation, more robust than a distributed counterpart for Max Flow. The issue is, therefore, what the restoration capacity penalty is if KSP is used instead of Max Flow. To explore this tradeoff, the authors present a comparative study of the effectiveness of KSP versus Max Flow as an alternative rerouting criteria in the context of transport network span restoration. The comparison applies to both centrally controlled and distributed restoration systems. Study methods include exhaustive span failure experiments on a range of network models, and parametric and analytical investigations for insight into the factors resulting in KSP versus Max Flow differences. The main finding is that KSP restoration capacity is more than 99.9% of that from Max Flow in typical network models. The hypothesis is made that a generalized "trap" topology is responsible for all KSP-Max Flow capacity differences. The hypothesis is tested experimentally and used to develop analytical bounds which agree well with observed results. These findings and data are relevant to standards makers and equipment developers in specifying and engineering future restorable networks. >
199 citations
NEC1
TL;DR: In order to achieve fast restoration, a distributed control mechanism that is applicable to both line and path restoration is proposed, and the shared use of spare channels for various failure scenarios, including multiple failure cases, are allowed.
Abstract: With the advent of networking technologies intelligent network elements, such as the digital cross-connect system (DCS), will make it possible to dynamically reconfigure a network for restoration purposes. Both restoration control of DCSs and spare-channel design issues are presented, and how they work together so that a fast and economical SONET self-healing network is obtained. In order to achieve fast restoration, a distributed control mechanism that is applicable to both line and path restoration is proposed. The proposed method allows the shared use of spare channels for various failure scenarios, including multiple failure cases, so that the efficient use of spare channels can be achieved. A linear-programming-based scheme is proposed to obtain spare-channel assignment, where a network-flow technique is used. Through a simulation study, a fast and economical self-healing network is verified. >
193 citations
"Optimal capacity placement for path..." refers background or methods in this paper
...Previous work used an IP approach based on -flow -cut considerations to solve the spare capacity placement problem in a span-restorable network [4], [11], [20]....
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...Issues related to the restoration mechanisms themselves are addressed in related works [1], [2], [4], [21], [27]....
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Proceedings Article•
01 Jan 1987
180 citations