Traffic Engineering Scheme Research Articles

Energy‐aware traffic allocation to optical lightpaths in multilayer core networks

SummaryThe amount of traffic that is generated by users and high‐demanding services is expected to rise dramatically in the forthcoming years. This will unavoidably deteriorate the performance and increase the consumed energy of core networks, thus constraining the growth of Internet. To this effect, multilayer traffic engineering schemes in IP/multiprotocol label switching over dense wavelength division multiplexing networks have been proposed for achieving improved performance and increased energy savings by flexibly allocating traffic to optical lightpaths. In particular, the consumed energy in a router can be minimized if the lightpaths are established so as to traverse a router without electronic processing and conversion of their signal between optical and electrical layer. Accordingly, this paper aims at providing an energy‐aware solution to the problem of traffic allocation to optical lightpaths in multilayer core networks. The problem is first formulated and then a solution based on a heuristic algorithm, called energy‐aware traffic allocation to optical lightpaths (ETAL) is proposed. The efficiency and worthiness of ETAL is validated through numerous scenarios and simulations. The derived results indicate that the proposed algorithm is an efficient traffic engineering solution that exhibits better performance in terms of consumed energy (up to 44%), when compared to other similar traffic allocation schemes. Copyright © 2015 John Wiley & Sons, Ltd.

Efficient Traffic Engineering Strategies for Optimizing Network Throughput in WDM All-Optical Networks

In this paper we investigate traffic-engineering issues in Wavelength Division Multiplexing (WDM) all- optical networks. In such networks, the wavelength continuity constraint along with the wavelength clash constraint, lead to poor network performances when dealing with the lightpath provisioning problem. The impact of these constraints is especially severe when traffic demands are unpredictable and characterized by random arrivals and departures. In order to alleviate the impact of these constraints, we propose to employ intentional/active rerouting. Active lightpath rerouting is to intentionally reroute already established lightpaths, during their life period, so as to achieve a better blocking performance. We here assume that due to the large geographic area an optical WDM network can cover, upgrading such a network to support the huge demand for network bandwidth can be costly. Thereby, it is extremely important for network operators to apply traffic-engineering strategies to cost-effectively optimize network throughput. Two new routing and wavelength assignment (RWA) algorithms applying intentional rerouting are proposed. Both algorithms dynamically reroute some already established lightpaths from longer paths to vacant shorter ones so as to reduce the network resources consumption and hence improve the network throughput. The first algorithm, namely, Timer-Based Active Lightpath Rerouting (TB-ALR) initiates the rerouting procedure every time a timer expires. The second algorithm, namely, Sequential Routing with Active Lightpath Rerouting (SeqRwALR) initiates the rerouting procedure when a connection leaves and its lightpaths are released. To the best of our knowledge, our global approach has not already been investigated in the literature. Simulation results show that the proposed active rerouting algorithms yield much lower connection rejection ratios than rerouting algorithms previously presented in the literature while rerouting a small number of already established lightpaths. By rerouting a small number of existing lightpaths, we hope that the disruption period incurred due to rerouting is minimized.

Identifying Large Flows Based on SDBF Algorithm in High Speed Network Measurement

It is very important in developing effective and efficient traffic engineering schemes for identifying large flows. In this paper, according to the characteristic of network flows, a new algorithm which combined by scalable bloom filter and dynamic bloom filter is proposed to realize elephant flows identification. This method can improve the performance of network measurement and the efficiency of the resource usage of measurement system by handling flows with different strategy according to its different feature. The theoretical analysis and the simulation result indicate that under the condition of existing some tolerable measurement error about the length of flows, our algorithm can identify elephant flows accurately, which reduce the storage space and improve the processing speed efficiently.

Using Sample and Multilayer Compressed Counting Bloom Filter Algorithm to Realize Elephant Flows Identification

It is very important in developing effective and efficient traffic engineering schemes for identifying elephant flows. In this paper, according to the base idea of Sample and Hold, a new algorithm is proposed to realize elephant flows identification. Compare to the original sample and hold algorithm, our algorithm save storage space and reduce false positive by handling large flows firstly, using Scalable Bloom Filter to identify sampled flows and using Multilayer Compressed Counting Bloom Filter to count flows. The theoretical analysis and the simulation result indicate that under the condition of existing some tolerable measurement error about the length of flows, our algorithm can identify elephant flows accurately, which reduce the storage space and improve the processing speed efficiently.

Calendaring for wide area networks

Datacenter WAN traffic consists of high priority transfers that have to be carried as soon as they arrive alongside large transfers with pre-assigned deadlines on their completion (ranging from minutes to hours). The ability to offer guarantees to large transfers is crucial for business needs and impacts overall cost-of-business. State-of-the-art traffic engineering solutions only consider the current time epoch and hence cannot provide pre-facto promises for long-lived transfers. We present Tempus, an online traffic engineering scheme that exploits information on transfer size and deadlines to appropriately pack long-running transfers across network paths and time, thereby leaving enough capacity slack for future high-priority requests. Tempus builds on a tailored approximate solution to a mixed packing-covering linear program, which is parallelizable and scales well in both running time and memory usage. Consequently, Tempus is able to quickly and effectively update its solution when new transfers arrive or unexpected changes happen. These updates involve only small edits to existing transfers. Therefore, as experiments on traces from a large production WAN show, Tempus can offer and keep promises to long-lived transfers well in advance of their actual deadline; the promise on minimal transfer size is comparable with an offline optimal solution and outperforms state-of-the-art solutions by 2-3X.

On IGP link weight optimization for joint energy efficiency and load balancing improvement

The energy consumption of backbone networks has risen exponentially during the past decade with the advent of various bandwidth-hungry applications. To address this serious issue, network operators are keen to identify new energy-saving techniques to green their networks. Up to this point, the optimization of IGP link weights has only been used for load-balancing operations in IP-based networks. In this paper, we introduce a novel link weight setting algorithm, the Green Load-balancing Algorithm (GLA), which is able to jointly optimize both energy efficiency and load-balancing in backbone networks without any modification to the underlying network protocols. The distinct advantage of GLA is that it can be directly applied on top of existing link-sleeping based Energy-aware Traffic Engineering (ETE) schemes in order to achieve substantially improved energy saving gains, while at the same time maintain traditional traffic engineering objectives. In order to evaluate the performance of GLA without losing generality, we applied the scheme to a number of recently proposed but diverse ETE schemes based on link sleeping operations. Evaluation results based on the European academic network topology GÉANT and its real traffic matrices show that GLA is able to achieve significantly improved energy efficiency compared to the original standalone algorithms, while also achieving near-optimal load-balancing performance. In addition, we further consider end-to-end traffic delay requirements since the optimization of link weights for load-balancing and energy savings may introduce substantially increased traffic delay after link sleeping. In order to solve this issue, we modified the existing ETE schemes to improve their end-to-end traffic delay performance. The evaluation of the modified ETE schemes together with GLA shows that it is still possible to save a significant amount of energy while achieving substantial load-balancing within a given traffic delay constraint.

Multi‐topology routing based egress selection approach to achieve hybrid intra‐AS and inter‐AS traffic engineering

SummaryHot‐potato routing is a border gateway protocol policy that selects the ‘closest’ egress router in terms of interior gateway protocol cost. This policy imposes inherent interactions between intra‐AS (Autonomous System) and inter‐AS traffic engineering. In light of this observation, we present a hybrid intra‐AS and inter‐AS traffic engineering scheme named egress selection based upon hot potato routing. This scheme involves link weight optimization, which can not only minimize the time that IP (Internet Protocol) packets travel across the network by assigning specified egress router but also balance the load among the internal links of the transit network. Egress selection based upon hot potato routing also incorporates multi‐topology routing technique to address the problem that one set of link weights might not guarantee specified egress routers. Accordingly, we formulate the link weights optimization problem using multi‐topology routing as a mixed integer linear programming model. And we present a new heuristic algorithm to make the problem tractable. Numerical results show that only a few topologies are needed to guarantee specified egress router, and maximum link utilization is also reduced. Copyright © 2014 John Wiley & Sons, Ltd.

Experimental Assessment of Bulk Path Restoration in Multi-layer Networks Using PCE-based Global Concurrent Optimization

Generalized multi-protocol label switching-based multi-layer networks (MLN) combining packet and optical switching lead to jointly leverage intrinsic per-layer benefits such as statistical multiplexing and huge transport capacity. By doing so, efficient network resource utilization is attained through MLN traffic engineering (TE) strategies, i.e. grooming. In this context, an optical link failure may cause the disruption of multiple groomed packet label switched paths (LSPs). Thereby, efficient recovery schemes such as restoration are required. In dynamic restoration, the centralized path computation element (PCE) sequentially computes backup paths for the set of failed packet LSPs using the TE database (TED). Since the TED is not updated until an LSP is actually set up, it is very likely that the PCE assigns the same network resources to different backup paths. This does increase resource contention and not fully exploits the potential grooming opportunities among the backup LSPs; consequently, the restorability metric performs poorly. To improve this, a designed PCE global concurrent optimization (GCO) architecture is implemented favoring grooming and lowering resource contention. The addressed problem, referred to as bulk path restoration in multi-layer optical networks (BAREMO), is formally modeled and stated using a mixed integer linear programming formulation. Then, a heuristic algorithm solving the BAREMO problem is devised. The experimental performance evaluation is conducted within the ADRENALINE testbed. Besides validating the PCE GCO architecture, its performance is compared with a sequential PCE for several traffic loads and failure rates. The results show that the PCE GCO improves remarkably restorability compared to the sequential PCE at the expenses, however, of increasing the restoration time.

Traffic Engineering of Peer-Assisted Content Delivery Network with Content-Oriented Incentive Mechanism

In content services where people purchase and download large-volume contents, minimizing network traffic is crucial for the service provider and the network operator since they want to lower the cost charged for bandwidth and the cost for network infrastructure, respectively. Traffic localization is an effective way of reducing network traffic. Network traffic is localized when a client can obtain the requested content files from other a near-by altruistic client instead of the source servers. The concept of the peer-assisted content distribution network (CDN) can reduce the overall traffic with this mechanism and enable service providers to minimize traffic without deploying or borrowing distributed storage. To localize traffic effectively, content files that are likely to be requested by many clients should be cached locally. This paper presents a novel traffic engineering scheme for peer-assisted CDN models. Its key idea is to control the behavior of clients by using content-oriented incentive mechanism. This approach enables us to optimize traffic flows by letting altruistic clients download content files that are most likely contributed to localizing traffic among clients. In order to let altruistic clients request the desired files, we combine content files while keeping the price equal to the one for a single content. This paper presents a solution for optimizing the selection of content files to be combined so that cross traffic in a network is minimized. We also give a model for analyzing the upper-bound performance and the numerical results.

Multi-Objective Traffic Engineering for Future Networks

An important goal towards the design of Future Networks is to achieve the best ratio of performance to energy consumption and at the same time assure manageability. This paper presents a general problem formulation for Energy-Aware Traffic Engineering and proposes a distributed, heuristic Energy-Aware Traffic Engineering scheme (ETE) that provides load balancing and energy-awareness in accordance with the operator's needs. Simulation results of ETE compared to the optimal network performance confirm the capability of ETE to meeting the needs of Future Networks.

Single-path and multi-path label switched path allocation algorithms with quality-of-service constraints: performance analysis and implementation in NS2

The choice of the path computation algorithm is a key factor to design efficient traffic engineering strategies in multi-protocol label switching networks and different approaches have been proposed in the literature. The effectiveness of a path computation algorithm should be evaluated against its ability to optimise the utilisation of network resources as well as to satisfy both current and future label switched paths allocation requests. Although powerful and flexible simulation tools might be useful to assist a network manager in the selection of proper algorithms, state-of-the-art simulators and network planning tools do not currently offer a suitable support. This study deals with the design and performance evaluation of multi-constraints path computation algorithms. To this aim, ad hoc software modules have been developed and integrated within the MTENS simulator. New single-path and multi-path computation algorithms have been proposed and compared in terms of number of accepted requests, success probability, network resources utilisation and execution time. Finally, some guidelines and recommendations for the selection of path computation algorithms have also been provided.

Traffic Engineering for Proactive Failure Recovery of IP Networks

As a promising approach to improve network reliability, proactive failure recovery (PFR) re-routes failure affected traffic to backup paths without waiting for the completion of IP routing convergence. However, the failure affected traffic may cause congestion if it is not carefully allocated over the backup paths according to their available capacity. A post failure traffic engineering (PostTE) scheme is proposed to balance the load in the PFR scheme. Loop-free backup paths are prepared in advance to cover all the potential single-link failures. The failure affected load is locally allocated to the backup paths through solving a linear programming (LP) problem. Most of the time, the maximum link utilization (MLU) of the network is minimized under both the failure and failure-free cases. For the tested education networks, the LP problem can be solved within milliseconds.

Detecting superpoints through a reversible counting Bloom filter

Internet attacks such as distributed denial-of-service (DDoS) attacks and worm attacks are increasing in severity. Identifying realtime attack detection and mitigation of Internet traffic is an important and challenging problem. For example, a compromised host doing fast scanning for worm propagation often makes an unusually high number of connections to distinct destinations within a short time. We call such a host a superpoint, which are sources that connect to a large number of distinct destinations. Detecting superpoints is very important in developing effective and efficient traffic engineering schemes. We propose two novel schemes for detecting superpoints and prove guarantees on their accuracy and memory requirements. These schemes are implemented by introducing a reversible counting Bloom filter (RCBF), a special counting Bloom filter. The RCBF consists of 4 hash functions which projectively select some consecutive bits from original strings as function values. We obtain the information of superpoints using the overlapping of hash bit strings of the RCBF. The theoretical analysis and experiment results show that our schemes can precisely and efficiently detect superpoints.

Autonomous traffic engineering with self-configuring topologies

Network operators use traffic engineering (TE) to control the flow of traffic across their networks. Existing TE methods require manual configuration of link weights or tunnels, which is difficult to get right, or prior knowledge of traffic demands and hence may not be robust to link failures or traffic fluctuations. We present a self-configuring TE scheme, SculpTE, which automatically adapts the network-layer topology to changing traffic demands. SculpTE is responsive, stable, and achieves excellent load balancing.

Load-Balanced IP Routing Scheme Based on Shortest Paths in Hose Model

This paper proposes a simple shortest-path-based load-balanced Internet-Protocol (IP) routing scheme based on the hose model. The proposed scheme is an extension of the Smart-OSPF (S-OSPF) scheme. The proposed scheme, the same as S-OSPF, splits traffic demand only at source edge nodes and transmits the traffic along the shortest path routes. In S-OSPF, the split ratios are determined for each source-destination edge node pair by assuming that the traffic demand between all source-destination edge node pairs are known, in other words, the exact traffic matrix is completely given. This, however, is difficult to measure and predict accurately because of the measurement costs and rapid traffic fluctuations. On the other hand, in the proposed scheme, we assume the use of the hose model; in this model, only the total amount of traffic that a node injects into the network and the total amount of traffic it receives from the network are known. This simplicity makes it easy for network operators to apply the hose model for IP routing. This is because measuring just the total amount of traffic is less expensive than measuring the traffic demands between all source-destination edge node pairs. In addition, the aggregated traffic exhibits less fluctuation and is easier to predict than the traffic demand between each source-destination pair. Any extension of the Linear Programming (LP) formulation that optimizes S-OSPF to suit the hose model cannot be solved as a simple LP problem, because the traffic matrix is not known. By introducing a duality theorem, we successfully formulate our problem as an LP formulation that can be easily solved yielding the desired split ratios. Numerical results show that the proposed scheme dramatically reduces the network congestion ratio compared to the classical shortest path routing scheme and it provides performance close to that provided by the sophisticated traffic-engineering (TE) scheme of Multi-Protocol Label Switching (MPLS)-TE.

Fine two-phase routing over shortest paths with traffic matrix

This paper presents an IP finely-distributed load-balanced routing scheme based on two-phase routing over shortest paths, where the traffic matrix is given. It is called the fine two-phase routing (F-TPR) scheme. F-TPR more finely distributes traffic from a source node to intermediate nodes than the original TPR. F-TPR determines the distribution ratios to intermediate nodes for each source–destination node pair independently. To determine an optimum set of distribution ratios, a linear programming (LP) formulation is derived. We compare the F-TPR scheme against the TPR scheme and the sophisticated traffic engineering (TE) scheme of Multi-Protocol Label Switching (MPLS-TE). Numerical results show that F-TPR greatly reduces the network congestion ratio compared to TPR. In addition, F-TPR provides almost the same network congestion ratios as MPLS-TE, the difference is surprisingly less than 0.1% for the various network topologies examined. In addition, considering the practical implementation of F-TPR for routers, we also investigate the case that traffic from a source node to a destination node is not allowed to be split over multiple routes. The non-split problem is formulated as an integer linear programming (ILP) problem. As it is difficult to solve the ILP problem within practical time, two heuristic algorithms are presented: Largest Traffic Demand First (LTDF) and a Random Selection (RS). The applicability of LTDF and RS are presented in terms of network size. We find that non-split F-TPR also matches the routing performance of MPLS-TE within an error of 1%, when network size is large enough.

Traffic Engineering in the Wavelength Domain for Optical Burst-Switched Networks

This paper addresses the possibility of using traffic engineering in the wavelength domain as a way to improve the performance of optical burst-switched (OBS) networks. With that aim, we detail a heuristic traffic engineering strategy that determines the order by which the ingress nodes of the network should search for an available wavelength for burst transmission, in order to minimize the probability that data bursts going through overlapping paths reach a common fiber link using the same wavelength. By means of network simulation, it is shown that the proposed traffic engineering strategy outperforms the existing strategies in reducing burst loss in OBS networks. This trend holds for core nodes with different degrees of wavelength conversion, ranging from the absence of wavelength converters to the use of dedicated full-range wavelength converters. More specifically, it is shown that using only traffic engineering in the wavelength domain can dramatically reduce burst loss in networks without wavelength conversion or alternatively it can reduce the number of wavelength converters in networks based on shared wavelength conversion. The simulation results also show that by combining traffic engineering in the wavelength domain with the use of the inexpensive electronic buffers at the ingress nodes, the performance of OBS networks with dedicated full-range wavelength converters can be further improved at the expense of a slight increase in the burst transfer delay.

Improving the Resilience of Emerging Generation GMPLS Networks

We propose a traffic engineering (TE) scheme that uses virtual preemption and configurable survivability to improve the resilience of the emerging-generation GMPLS networks. Virtual preemption ranks the rerouting requests based on bandwidth granularity and, using this ranking, reroutes these requests to allow the highest-bandwidth-demanding requests to be rerouted first with the expectation of achieving higher restorability. Configurable survivability moves the network operating conditions close to a predefined performance pattern and balances the routing configuration to improve the network survivability. Simulation reveals that the proposed TE scheme can increase the survivability of a network and achieve higher restorability while maintaining the signaling efficiency at an acceptable level.

F-TPR: fine two-phase IP routing scheme over shortest paths for hose model

This letter proposes an IP-based finely-distributed routing scheme based on two-phase routing (TPR) over shortest paths for the hose model. It is called the fine-TPR (F-TPR) scheme. Compared to the original TPR, F-TPR distributes traffic from a source node to intermediate nodes more finely, where the distribution ratio is determined for each source-destination pair. To determine an optimum set of the distribution ratios, we successfully formulate our problem as a quadratic constraint programming (QCP) formulation that can be solved by using a mathematical programming solver. Numerical results show that F-TPR greatly outperforms TPR and its performance approaches that provided by the sophisticated traffic engineering (TE) scheme of multi-protocol label switching (MPLS-TE).

A service differentiation and traffic engineering scheme for mobile ad hoc networks

Actually with the increasing popularity of wireless networks, which indicate that there will be a demand for communicating devices providing high capacity communication with Quality of Service (QoS), QoS becomes an important factor in wireless networks, because it offers to the network the ability to provide services to applications with some important requirements. In this paper, we describe a new approach for traffic engineering for QoS support in the wireless IEEE 802.11b. This new scheme is based on a multiple queuing system to provide service differentiation for user's flows. We investigate and analyse the performance of this approach through a set of simulations and compare its performance with the original IEEE 802.11b protocol. Using simulation results, we show the effectiveness of the proposed approach and the outperformance of the IEEE 802.11b in terms of throughput and packet loss rate.