Design and analysis of partial protection mechanisms in groomed optical WDM mesh networks
TL;DR: The mechanism proposed to counter backup contention is seen to provide an average of 120% reduction in the contention among backup paths of connections traversing a link, especially when the number of wavelengths in each link is small.
Abstract: We consider the problem of survivable network design in traffic-groomed optical WDM mesh networks that support subwavelength capacity connections. In typical survivable network designs, individual sessions are provided either full protection or no protection. We consider a quality of protection (QoP) framework where a connection is provided partial protection, i.e., when a link failure occurs on the primary path, the protection bandwidth provided on the backup path is less than or equal to the primary bandwidth. Each connection request specifies the primary bandwidth and a minimum backup bandwidth required. The network will guarantee at least the minimum backup bandwidth and, if capacity is available, higher backup bandwidth up to the primary path's bandwidth. The advantage of such a model is that it can reduce backup capacity requirements based on connection needs leading to lower blocking probability and lower network costs. We consider two scenarios: (i) a network with static traffic that is designed using an integer linear program (ILP) formulation and (ii) a network with dynamic traffic for which we present a heuristic connection admission control algorithm that prevents backup resource contention during recovery from a link failure. The results quantify the gain in blocking probability for different partial protection scenarios. The mechanism proposed to counter backup contention is seen to provide an average of 120% reduction in the contention among backup paths of connections traversing a link, especially when the number of wavelengths in each link is small.
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TL;DR: This work proposes a mixed-integer-linear-program (MILP) solution and a computationally efficient heuristic, and considers two partial-protection models to support degraded services in mixed-line-rate networks.
Abstract: Traffic in optical backbone networks is increasing and becoming more heterogeneous with respect to bandwidth and QoS requirements due to the popularity of high-bandwidth services (such as cloud computing, e-science, telemedicine, etc.), which need to coexist with traditional services (HTTP, etc.). Mixed-line-rate (MLR) networks that support lightpaths of different rates such as 10, 40, 100 Gb/s, etc., are being studied to better support the heterogeneous traffic demands. Here, we study the important topic of degraded services in MLR networks, where a service can accept some degradation (i.e., reduction) in bandwidth in case of a failure in exchange for a lower cost, a concept called partial protection. Network operators may wish to support degraded services to optimize network resources and reduce cost. We propose using multipath routing to support degraded services in MLR networks, a problem that has not been studied before and is significantly more challenging than in single-line-rate (SLR) networks. We consider minimum-cost MLR network design (i.e., choosing which transponder rates to use at each node), considering the opportunity to exploit multipath routes to support degraded services. We propose a mixed-integer-linear-program (MILP) solution and a computationally efficient heuristic, and consider two partial-protection models. Our illustrative numerical results show that significant cost savings can be achieved due to partial protection versus full protection and is highly beneficial for network operators. We also note that multipath routing in MLR networks exploits volume discount of higher-line-rate transponders by cost-effectively grooming requests over appropriate line rates to maximize transponder reuse versus SLR.
25 citations
Cites background from "Design and analysis of partial prot..."
...We also note that multipath routing in MLR networks exploits volume discount of higher-line-rate transponders by cost-effectively grooming requests over appropriate line rates to maximize transponder reuse versus SLR. Index Terms Degraded service, mixed-line-rate (MLR) network, multipath…...
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01 Dec 2011
TL;DR: A multipath routing scheme to support degraded services in MLR networks is developed, and illustrative examples show that significant cost savings can be achieved vs. full protection.
Abstract: Traffic in optical backbone networks is increasing and becoming heterogeneous with respect to bandwidth and QoS requirements due to the popularity of high-bandwidth services such as cloud computing, e-science, telemedicine, etc which need to coexist with traditional services (HTTP, etc) Mixed-line-rate (MLR) networks which support lightpaths of different rates are being studied to support the heterogeneous traffic demands Here, we study the important topic of degraded services in MLR networks, where a service can accept degradation in bandwidth to a certain extent in case of a failure for lower cost, a concept called partial protection Network operators may wish to support degraded services to optimize network resources and reduce cost We develop a multipath routing scheme to support degraded services in MLR networks, and our illustrative examples show that significant cost savings can be achieved vs full protection
6 citations
Cites background from "Design and analysis of partial prot..."
...In [3] [4], the authors present degraded services and partial protection approaches in single-line-rate (SLR) networks and the authors in [4] consider only dedicated partial protection....
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...As Internet applications are becoming more critical and diverse, meeting quality of service (QoS) needs such as bandwidth, latency, jitter, etc. is crucial [3] [4] [5]....
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20 Nov 2009
TL;DR: It is proposed that the main traffic types of today's applications should be carried using the following features: connection-oriented service, traffic grooming to fill those connection oriented pipes, and forward error recovery with protection provided in the physical layer.
Abstract: Today networks are too cumbersome due to the incoherent integration of various technologies developed over time. Convergence of data, voice, and video has caused the retro-fitting of a network to support non-native traffic types and this has led to sub-par performance for every traffic type. Fundamental changes are warranted to support high bandwidth traffic. The network must guarantee end-to-end delivery and provide inherent protection within the physical structure. We propose that the main traffic types of today's applications should be carried using the following features: connection-oriented service, traffic grooming to fill those connection oriented pipes, and forward error recovery with protection provided in the physical layer. We present some of our research results.
5 citations
Cites background from "Design and analysis of partial prot..."
...We propose that future network should be designed with the two prominent features, traffic grooming [8], [9], [10], [11], [12], [13], [14], [15] and providing protection [16], [17], [18], [19] in the physical layer....
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TL;DR: The proposed SPXP algorithm reduces the recovery time by ensuring that backup resources are pre‐configured along each backup segment and, hence, is readily available upon a failure.
Abstract: We propose a new approach for developing segment-based schemes for protection against single link/node failure in wavelength division multiplexing (WDM) mesh networks. In the proposed approach, every request is allocated a pair of link disjoint but most coupled primary and backup paths. Two paths are said to be most coupled if they share the maximum number of end nodes of some existing requests. Coupled paths reduce the total number of hops need to be traversed by a failure signal and, hence, potentially reduces the overall recovery time. We show that the problem of finding a pair of disjoint and most coupled paths is NP-complete. Accordingly, we propose an efficient and fast protection algorithm called SPXP—Segment Pre-Cross-Connected Protection, to allocate disjoint and most coupled paths. The proposed SPXP algorithm reduces the recovery time by ensuring that backup resources are pre-configured along each backup segment and, hence, is readily available upon a failure. Simulation results for different incremental traffic models and network topologies show that, for most cases, the proposed SPXP exhibits better performance in terms of blocking probability, resource usage, and recovery time compared with existing protection schemes. Copyright © 2010 John Wiley & Sons, Ltd.
3 citations
Cites background from "Design and analysis of partial prot..."
...In [4], the problem of survivable network design in traffic-groomed optical WDMmesh networks that support subwavelength capacity connections is addressed....
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02 Nov 2009
TL;DR: It is proposed that the main traffic types of today's applications should be carried using the following features: connection-oriented service, traffic grooming to fill those connection oriented pipes, and forward error recovery with protection provided in the physical layer.
Abstract: Internet services and applications require high reliability and different bandwidth that need to be supported over the high capacity wavelength channels. We will present a short overview of issues in design of wavelength division multiplexing, efficient protection, and access and grooming mechanisms to make the network transparent, scalable, reliable, and simple. Article not available.
3 citations
Cites background from "Design and analysis of partial prot..."
...We propose that future network should be designed with the two prominent features, traffic grooming [8], [9], [10], [11], [12], [13], [14], [15] and providing protection [16], [17], [18], [19] in the physical layer....
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References
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01 Jan 2002
TL;DR: Various network and node architectures for different traffic -grooming scenarios are compared and discussed and it is expected that there will be much more interest on the mesh topology suitable for long-haul, widearea networks.
Abstract: The transmission capacity of a link in today’s optical networks has increased significantly due to wavelength-division multiplexing (WDM) technology. The network performance is now mainly limited by the processing capability of the network elements, which are mainly electronic. By efficiently grooming low-speed traffic streams onto high-capacity optical channels, it is possible to minimize this electronic processing and eventually increase the network performance. Traffic grooming is an emerging topic that has been gaining more research and commercial attention. Most previous research on traffic grooming is mainly based on the ring network topology. It is expected that there will be much more interest on the mesh topology suitable for long-haul, widearea networks. This paper reviews most of the recent research work on traffic grooming in WDM ring and mesh networks. Various network and node architectures for different traffic -grooming scenarios are compared and discussed. * This work has been supported by the National Science Foundation (NSF) under Grant Nos. NCR-9508239 andANI-9805286, and by Sprint Advanced Technology Laboratories (ATL).
273 citations
TL;DR: This work investigates the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM), and proposes effective heuristics for grooming a connection request with shared protection.
Abstract: We investigate the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM). In the dynamic provisioning context, a typical connection request may require bandwidth less than that of a wavelength channel, and it may also require protection from network failures, typically fiber cuts. Based on a generic grooming-node architecture, we propose three approaches for grooming a connection request with shared protection: protection-at-lightpath level (PAL); mixed protection-at-connection level (MPAC); separate protection-at-connection level (SPAC). In shared-mesh protection, backup paths can share resources as long as their corresponding working paths are unlikely to fail simultaneously. These three schemes explore different ways of backup sharing, and they trade-off between wavelengths and grooming ports. Since the existing version of the problem for provisioning one connection request with shared protection is NP-complete, we propose effective heuristics. Under today's typical connection-bandwidth distribution where lower bandwidth connections outnumber higher bandwidth connections, we find the following: 1) it is beneficial to groom working paths and backup paths separately, as in PAL and SPAC; 2) separately protecting each individual connection, i.e., SPAC, yields the best performance when the number of grooming ports is sufficient; 3) protecting each specific lightpath, i.e., PAL, achieves the best performance when the number of grooming ports is moderate or small.
171 citations
07 Nov 2002
TL;DR: The results show that the use of TDM provides substantial gains, especially for multi-fiber networks, and simulation based analyses are used to compare the proposed TDM architecture to traditional WR networks, both with and without wavelength conversion.
Abstract: We study routing and wavelength assignment for a circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM network. In a conventional WR network, an entire wavelength is assigned to a given session (or circuit). This can lead to lower channel utilization when the individual sessions do not need the entire channel bandwidth. We consider a TDM-based approach to reduce this inefficiency. In this architecture, each wavelength is partitioned in the time-domain into fixed-length time-slots organized as a TDM frame. Multiple sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each session. Thus, given a session request with a specified bandwidth, the goal is to determine the route, wavelength and time-slot assignment (RWTA) that meets the request. This is similar to routing and wavelength assignment in WR networks. We present a family of RWTA algorithms and study the blocking performance. We use the existing shortest-path routing algorithm with a new link cost function, least resistance weight (LRW) function, that incorporates wavelength utilization information. We employ the known least loaded (LL) wavelength selection and present three variations of the least-loaded time-slot (LLT) algorithm. Simulation based analyses are used to compare the proposed TDM architecture to traditional WR networks, both with and without wavelength conversion. The goal is to compare the benefits of TDM and wavelength conversion towards improving performance in WR networks. The results show that the use of TDM provides substantial gains, especially for multi-fiber networks.
120 citations
09 Aug 2001
TL;DR: A quantitative framework for best- effort protection of the optical layer is discussed, providing a way to bridge the gap between two known protection grades of fully protected connections vis-a-vis unprotected protection.
Abstract: In this paper we discuss a quantitative framework for best- effort protection of the optical layer. This framework provides a way to bridge the gap between two known protection grades of fully protected connections vis-a-vis unprotected protection. The framework allows to specify the probability with which the connection will be protected, providing the customer with a full range of protection guarantees at possibly different prices. Since connections may be partially protected, the required protection bandwidth can be reduced. The amount of protection bandwidth is shown to depend on an 'equivalent survivable bandwidth.' The framework also extends to preemptable (low priority) connections and to different ring architectures.
112 citations
09 Aug 2001
TL;DR: A dynamic algorithm to obtain the optimal spare capacity on a wavelength on a link when a number of backup traffic streams are multiplexed onto it is presented.
Abstract: This paper addresses the problem of dynamically establishing dependable low-rate traffic stream connections in WDM mesh networks with traffic grooming capabilities. To establish a dependable connection, we set up link-disjoint primary and backup traffic stream paths between the source and destination and use backup multiplexing to reduce the overhead of backup traffic streams. We present a dynamic algorithm to obtain the optimal spare capacity on a wavelength on a link when a number of backup traffic streams are multiplexed onto it. We propose two schemes for grooming traffic streams onto wavelengths: Mixed Primary-Backup Grooming Policy (MGP) and Segregated Primary-Backup Grooming Policy (SGP). We illustrate how these schemes can be applied in a WDM mesh network scenario along with a routing and wavelength assignment algorithm. We conduct simulation experiments to evaluate the effectiveness of the proposed schemes on different network topologies, using different routing and wavelength assignment methods. The effect of change in granularity and change in the number of alternate paths on the grooming policies are also presented. From the simulation results, it is inferred that SGP is useful in network topologies, such as mesh-torus, characterized by good connectivity and a good amount of traffic switching and mixing at the nodes. On the other hand, MGP is useful in network topologies, such as a ring, characterized by low connectivity and high load correlation.
91 citations