共查询到20条相似文献,搜索用时 46 毫秒
1.
RATES: a server for MPLS traffic engineering 总被引:1,自引:0,他引:1
It has been suggested that one of the most significant reasons for multiprotocol label switching (MPLS) network deployment is network traffic engineering. The goal of traffic engineering is to make the best use of the network infrastructure, and this is facilitates by the explicit routing feature of MPLS, which allows many of the shortcomings associated with current IP routing schemes to be addressed. This article describes a software system called Routing and Traffic Engineering Server (RATES) developed for MPLS traffic engineering. It also describes some new routing ideas incorporated in RATES for MPLS explicit path selection. The RATES implementation consists of a policy and flow database, a browser-based interface for policy definition and entering resource provisioning requests, and a Common Open Policy Service protocol server-client implementation for communicating paths and resource information to edge routers. RATES also uses the OSPF topology database for dynamically obtaining link state information. RATES can set up bandwidth-guaranteed label-switched (LSPs) between specified ingress-egress pairs. The path selection for LSPs is on a new minimum-interference routing algorithm aimed at making the best use of network infrastructure in an online environment where LSP requests arrive one by one with no a priori information about future requests. Although developed for an MPLS application, the RATES implementation has many similarities in components to an intradomain differentiated services bandwidth broker 相似文献
2.
This paper reports on a novel strategy and related algorithm for realizing dynamic routing and grooming into wavelengths of data flows (label switched paths, LSPs) in new generation optical networks based on generalized MPLS (GMPLS). The method allows arbitrary granularities of LSPs. The new generation network is modeled as a multi-layer network consisting of an IP/MPLS layer and an optical layer. In particular, the proposed solution adopts a dynamic routing algorithm based on the Dijkstra algorithm, that makes use of a weight system, integrated with a suitable method for grooming LSPs into wavelengths based on the packing criterion, thus harmonizing the features of MPLS packet flows whose bandwidth vary in a continuous range of values, with the optical world, where the wavelength bandwidth ranges according to discrete values. The weight system is based on the concepts of least resistance routing that allows to evenly distribute the traffic at the MPLS layer, while packing improves the use of optical resources by favoring more filled wavelengths with respect to the emptier ones. To assess the validity of the proposed solution a simulation model has been realized. The results obtained by simulation show that the packing criterion allows reducing the refused bandwidth from two down to about four times, for a network load of 70% and 55%, respectively, when compared with the alternative method named spreading. The dependence of the proposed solution on bandwidth granularity has been also investigated. Moreover, in order to demonstrate the superior performance of the proposed routing solution, a comparison between the proposed strategy with relevant solutions known in the literature, based on either a single or multi-layer approach, is also reported. In order to perform the comparison, all the reference routing solutions that have been considered adopt the packing method for LSP grooming into the lightpaths. The results show that our solution outperforms the others in terms of amount of traffic that can be on-line accommodated. For instance, assuming a blocking probability of 10–3, the proposed solution is able to further reduce the refused bandwidth of the best routing algorithm considered in the analysis by a factor of three times, thanks to the knowledge of optical resource availability. 相似文献
3.
In dynamic IP-over-WDM networks efficient fault-management techniques become more difficult since as demands change with time the optimal logical topology varies as well. Changes in the virtual topology should be done with care because working IP LSPs routed on top of a virtual topology should not be interrupted. Reconfiguration of the virtual topology may also affect precomputed backup IP LSPs to be activated in case of failure meaning that backup IP LSPs would need to be recomputed after any change in the virtual topology. A good sense solution can be the dimensioning of the virtual topology for a worst case traffic scenario, having as goal the minimization of the network cost, for example, and then route dynamic IP LSPs on this virtual topology. The virtual topology would remain unchanged as long as possible, that is, until changes in the virtual topology are considered to bring considerable benefits. Since data services over IP are essentially of a best-effort nature, protection could be provided, using IP LSP protection, only when bandwidth is available in the virtual topology. The computation of backup IP LSPs does not interfere with working IP LSPs meaning that no service interruption will exist. Such a strategy, considered in this paper, allows resources to be used efficiently, since free bandwidth is used for backup purposes, while the normal delivery of traffic is guaranteed in peak traffic situations although having no protection guarantees. Our main objective is to quantify the spare capacity, which can be used for restoration (backup) purposes, over a virtual topology designed and optimized to carry a traffic scenario with no survivability and QoS requirements. We analyse the maximum protection (MP) problem in such IP-over-WDM network environment. Protection is provided to IP LSP requests whenever possible through bandwidth reservation in a backup IP LSP on the virtual topology. Besides the mathematical formalization of the MP problem, an upper bound and heuristic algorithms are proposed and evaluated. The traffic considered includes IP LSPs of different granularities and is the worst case traffic scenario for which the network should be dimensioned. 相似文献
4.
Due to the explosive growth of data-related traffic driven by the Internet, network reliability becomes an important issue. We investigate various protection approaches to handle failures for dynamic traffic demands in IP/MPLS-over-WDM networks. An LSP can be protected at either the IP/MPLS layer or the optical layer. In IP/MPLS layer protection, an LSP is protected by providing a link-disjoint backup LSP between its end nodes. In optical layer protection, an LSP is protected by the backup lightpath of each lightpath traversed by the LSP. We present two integrated routing algorithms: hop-based integrated routing algorithm and bandwidth-based integrated routing algorithm (BIRA) to set up the restorable bandwidth-guaranteed paths efficiently. Then we present a multilayer protection scheme for multiclass traffic in such networks. This scheme takes into account the different QoS and recovery requirements of the traffic to provide protection capability either at the MPLS layer or at the optical layer in a cost-effective manner. We use the connection blocking probability and number of optical-electrical-optical conversions as performance metrics to compare various protection approaches. 相似文献
5.
6.
7.
8.
Network control for IP-over-optical networks can be classified as falling under the overlay, augmented, or peer models. In the first two models, the IP layer and the optical layer only have the resource information of their respective layers. In the peer model, all the resource information is known to both layers; hence, it can potentially achieve better resource utilization. Unfortunately, the peer model approach is generally not acceptable to the operators if the IP layer and optical layer belong to two different administrations. In addition, it is much more complex and generally seen as not feasible in the near future In this paper, we propose an enquiry-based provisioning scheme based on the overlay model which can, however, utilize resources in both layers as in the peer model approach. Two simple and novel algorithms for routing labeled-switched path (LSP) requests for this provisioning scheme are proposed. Simulation results show that our proposed algorithms perform significantly better than other routing algorithms for the overlay model and are nearly as good as the integrated routing algorithm for the peer model. 相似文献
9.
Bart Puype Eva Marín-Tordera Didier Colle Sergio Sánchez-López Mario Pickavet Xavier Masip-Bruin Piet Demeester 《Photonic Network Communications》2012,23(2):172-182
Multilayer traffic engineering (MLTE) allows coping with ever-increasing and varying traffic demands in IP-over-Optical multilayer
networks. It utilizes cross-layer TE (Traffic Engineering) techniques to provision optical lightpath capacity to the IP/MPLS
(Internet Protocol/ Multi-Protocol Label Switching) logical topology on-demand. Such provisioning however causes optical connection
arrival rates that pose strong performance requirements to Routing and Wavelength Assignment (RWA) strategies. Collecting
up-to-date network information for the RWA with rapidly changing network states can be quite difficult. Exposing optical layer
state information to the IP layer in the overlay model, or transforming this optical layer information in a workable representation
in an integrated control plane is similarly problematic. Prediction-Based Routing (PBR) has been proposed as a RWA mechanism
for optical transport networks; it bases routing not on possibly inaccurate or outdated network state, but instead on previous
connections set-up. In this article, we propose to implement PBR as the RWA mechanism in the optical layer of a multilayer
network, and use the predictive capabilities of PBR to expose dynamic optical network information into the multilayer traffic
engineering algorithm with minimal control plane overhead. Some simulations show the benefits of using the PBR in the optical
layer for MLTE purposes. 相似文献
10.
11.
为了优化利用IP层和WDM层网络资源,在WDM网络集成辅助图模型的基础上,提出了一种面向IP/GMPLS over WDM网络的基于代价的优化综合路由算法,即CIR(Cost-basedIntegrated Routing).该算法将IP层和WDM层资源可用信息以代价函数形式给出,并将因网络拓扑结构和网络负载分布不均衡等产生的瓶颈链路以及带宽碎片问题也统一纳入考虑,由此将LSP建立问题转化为在集成辅助图上找出一条源、目的节点之间的最短通路问题.仿真结果表明:CIR算法有效地实现了IP和WDM两层资源的联合优化,提高了网络资源利用,降低了网络阻塞率. 相似文献
12.
13.
Péter Fodor Gábor Enyedi Gábor Rétvári Tibor Cinkler 《Photonic Network Communications》2009,18(3):300-313
We address the problem of routing Label Switched Paths (LSPs) in multi-layer networks based on the Generalized MultiProtocol
Label Switching (GMPLS) paradigm. In particular, we pursue policies for choosing the appropriate layer to host a new LSP request,
as we find that such layer-preference policies have significant impact on network performance. We discuss several simple layer-preference
policies and we reveal why these simple policies ruin network performance in the long run. Consequently, we develop an efficient
heuristics, the Min-phys-hop routing and wavelength assignment algorithm, to govern the selection of the best layer of a multi-layer network in which
to host new LSP requests. We discuss the applicability of this algorithm with respect to the state-of-the-art GMPLS standards,
above all, the GMPLS routing extensions to OSPF-TE. By extensive simulations, we justify that the Min-phys-hop algorithm produces
close-to-optimal blocking and resource consumption under almost all possible selections of input parameters, and this is regardless
of the wavelength and Optical-Electrical-Optical (OEO) conversion capability present in the network. 相似文献
14.
Hongyi Xie Yanhe Li Xiaoping Zheng Xinyou Cui Yining Cao Hanyi Zhang 《Photonic Network Communications》2007,14(2):103-109
From both user and operator perspectives, fairness is an important aspect in IP-over-WDM networks where Label Switched Paths
(LSPs) are dynamically groomed over optical networks. The setup of LSPs with long distances experiences a higher blocking
probability due to both lightpath establishment unfairness in the optical layer and link cascading effect in the IP/MPLS layer.
A simple LSP connection admission and fairness control mechanism is proposed in this article. This control mechanism is based
on hop constraint, in which an LSP is accepted with a pre-assigned probability according to its distance and the hops of its
route. Through suppressing connection of short-distance LSPs that overuse bandwidth to facilitate the setup of LSPs with long
distances, this proposal achieves fine distance fairness performance with a slight overall blocking probability increment. 相似文献
15.
研究了在基于GMPLS的WDM网络中,当节点不具备波长变换能力并且配备有限个光收发器对时,如何为到达的业务请求建立标记交换路径(LSP)的问题。提出一种以跳数和带宽碎片要求为权重,合理分配带宽资源的新算法。仿真结果表明,该算法在保证用户业务可靠性要求的同时,能够更有效地提高全网资源的利用率,并大大降低网络阻塞的可能性。 相似文献
16.
Kar K. Kodialam M. Lakshman T.V. 《Selected Areas in Communications, IEEE Journal on》2000,18(12):2566-2579
This paper presents new algorithms for dynamic routing of bandwidth guaranteed tunnels, where tunnel routing requests arrive one by one and there is no a priori knowledge regarding future requests. This problem is motivated by the service provider needs for fast deployment of bandwidth guaranteed services. Offline routing algorithms cannot be used since they require a priori knowledge of all tunnel requests that are to be rooted. Instead, on-line algorithms that handle requests arriving one by one and that satisfy as many potential future demands as possible are needed. The newly developed algorithms are on-line algorithms and are based on the idea that a newly routed tunnel must follow a route that does not “interfere too much” with a route that may he critical to satisfy a future demand. We show that this problem is NP-hard. We then develop path selection heuristics which are based on the idea of deferred loading of certain “critical” links. These critical links are identified by the algorithm as links that, if heavily loaded, would make it impossible to satisfy future demands between certain ingress-egress pairs. Like min-hop routing, the presented algorithm uses link-state information and some auxiliary capacity information for path selection. Unlike previous algorithms, the proposed algorithm exploits any available knowledge of the network ingress-egress points of potential future demands, even though the demands themselves are unknown. If all nodes are ingress-egress nodes, the algorithm can still be used, particularly to reduce the rejection rate of requests between a specified subset of important ingress-egress pairs. The algorithm performs well in comparison to previously proposed algorithms on several metrics like the number of rejected demands and successful rerouting of demands upon link failure 相似文献
17.
A next-generation optical regional access network 总被引:2,自引:0,他引:2
Kuznetsov M. Froberg N.M. Henion S.R. Rao H.G. Korn J. Rauschenbach K.A. Modiano E.H. Chan V.W.S. 《Communications Magazine, IEEE》2000,38(1):66-72
We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks 相似文献
18.
研究了在基于GMPLS的WDM网络中,当节点不具备波长变换能力并且配备有限个光收发器对时,如何为到达的业务请求建立标记交换路径(LSP)的问题。提出一种以跳数和带宽碎片要求为权重,合理分配带宽资源的新算法。仿真结果表明,该算法在保证用户业务可靠性要求的同时,能够更有效地提高全网资源的利用率,并大大降低网络阻塞的可能性。 相似文献
19.
In this article, we consider traffic grooming and integrated routing in IP over WDM networks. The challenges of this problem
come from jointly considering traffic grooming, IP routing, and lightpath routing and wavelength assignment (RWA). Due to
the high bandwidth of optical fiber, there exists a mismatch between the capacity needed by an IP flow and that provided by
a single lightpath. Traffic grooming is therefore used to increase the network utilization by aggregating multiple IP flows
in a single lightpath. However, traffic grooming incurs additional delays that might violate Quality-of-Service (QoS) requirements
of IP users. In this work, the tradeoff between traffic grooming and IP QoS routing is well-formulated as a mixed integer
and linear optimization problem, in which the revenue from successfully provisioning IP paths is to be maximized. Problem
constraints include IP QoS, routing, optical RWA, and the WDM network capacity. We propose a novel Lagrangean relaxation (LGR)
algorithm to perform constraint relaxation and derive a set of subproblems. The Lagrangean multipliers are used in the proposed
algorithm to obtain a solution in consideration of grooming advantage and resource constraints simultaneously. Through numerical
experiments and comparisons between the proposed algorithm and a two-phase approach, LGR outperforms the two-phase approach
under all experimental cases. In particular, the improvement ratio becomes even more significant when the ratio of IP flow
to the wavelength capacity is smaller. 相似文献
20.
Walter Colitti Kris Steenhaut Didier Colle Mario Pickavet Jan Lemeire Ann Nowé 《Photonic Network Communications》2011,21(3):238-252
The Internet traffic evolution has forced network operators to migrate toward an integrated infrastructure which brings the
IP and optical layers under a unified model. The integration between the two technologies has been facilitated by the development
of the Generalized Multi Protocol Label Switching. In the integrated scenario, Multilayer Traffic Engineering can be reinforced
with integrated routing techniques. Integrated IP/WDM routing facilitates the routing decision phase by allowing a node to
have a complete knowledge of the IP and WDM domains when accommodating traffic. This study focuses on integrated IP/WDM routing.
We analyze two basic policies widely discussed in literature: one policy prioritizes the traffic accommodation on the virtual
topology, while the other prioritizes the traffic accommodation on the physical topology. We show that both the mechanisms
do not lead to efficient resource utilization because they tend to congest one layer more than the other one. We propose an
adaptive heuristic which combines the advantages of both the policies. When accommodating traffic, the proposed approach selects
the appropriate layer depending on the resource utilization being experienced in the virtual and the physical topologies.
We demonstrate via simulations that the cross-layer resource optimization executed by the proposed scheme achieves significant
improvements in terms of blocking ratio. 相似文献