Traffic Engineering Extensions Research Articles

Design of IP tunneling for OSPF network to reduce advertising delay

Abstract: An IP tunneling design scheme to reduce advertising delay inopen shortest path first (OSPF) networks, in which the link load is requiredfor traffic maintenance, is proposed. A controller and nodes are consisted in anetwork. A node sends an OSPF traffic engineering (OSPF-TE) advertise-ment when either link load or topology is changed. The controller determinesand adjusts the routes in the network to avoid traffic congestion. Thecontroller may experience delay in receiving advertisements due to OSPFforwarding delay. Therefore, route adjustment may be delayed. In theproposed scheme, an IP tunneling technique is used instead of the OSPFmechanism.Keywords: network management, IP networks, open shortest path firsttraffic engineer (OSPF-TE), IP tunnelingClassification: Network Management/OperationReferences [1] E. Oki and A. Iwaki, “Load-balanced IP routing scheme based on shortest paths inhose model,” IEEE Trans. Commun., vol. 58, no. 7, pp. 2088–2096, Jul. 2010.DOI:10.1109/TCOMM.2010.07.090219[2] D. Katz et al., “Traffic Engineering (TE) Extensions to OSPF Version 2,” RFC3630, Sep. 2003.[3] H. M. Alnuweiri, L. Y. K. Wong, and T. Al-Khasib, “Performance of new link stateadvertisement mechanisms in routing protocols with traffic engineering exten-sions,” IEEE Commun. Mag., vol. 42, no. 5, pp. 151–162, 2004. DOI:10.1109/MCOM.2004.1299361[4] Y. Koizumi, T. Miyamura, S. Arakawa, E. Oki, K. Shiomoto, and M. Murata,“Adaptive virtual network topology control based on attractor selection,” IEEE/OSA J. Light. Tech., vol. 28, no. 11, pp. 1720–1731, Jun. 2010. DOI:10.1109/JLT.2010.2048412[5] Y. Lee et al., “Path Computation Element Communication Protocol (PCEP)requirements and protocol extensions in support of global concurrent optimization,”RFC 5557, Jul. 2009.[6] C. Perkins, “IP encapsulation within IP,” RFC 2003, Oct. 1996.[7] “What is propagation delay? (Ethernet Physical Layer)”, Ethernet FAQ, http://stason.org/TULARC/networking/lans-ethernet/3-11-What-is-propagation-delay-Ethernet-Physical-Layer.html, Oct. 21. 2010.

Collision-Aware Routing and Spectrum Assignment in GMPLS-Enabled Flexible-Bandwidth Optical Network

In a flexible-bandwidth optical network (FBON) with a generalized multiprotocol label switching control plane, the resource reservation protocol with traffic engineering extensions (RSVP-TE) is employed to establish end-to-end bandwidth variable lightpaths. The resource reservation can be blocked due to spectrum contention of different concurrent RSVP instances (called backward blocking), and it is the predominant blocking contribution when traffic load is low and arrival highly dynamic. Also, due to its flexible traffic granularity in FBON, the backward collision would happen more frequently and the collision scenario would be more complicated than that in wavelength-routed networking; thus the need for a collision evaluation and avoiding method. So, a collision-avoiding routing with maximum available spectrum allocation (SA) options and an SA scheme to search the spectrum segment with minimum collision possibility are proposed for backward blocking reduction, as well as an extension to the RSVP-TE. Simulation results show that the proposed algorithm could achieve better blocking performance through significantly reducing the backward reservation collision but with acceptable forward blocking deterioration. At the same time, with the proposed algorithm, different granularity traffic could be served more fairly in FBON.

Distributed Sharing of Functionalities and Resources in Survivable GMPLS-Controlled WSONs

Sharing of functionalities and sharing of network resources are effective solutions for improving the cost-effectiveness of wavelength-switched optical networks (WSONs). Such cost-effectiveness should be pursued together with the objective of ensuring the requested level of performance at the physical layer (i.e., quality of transmission, QoT) and at the upper layer also in the case of a failure (i.e., survivability). This paper aims to apply the sharing concept to a WSON with QoT and survivability requirements (against single-link failures). QoT is guaranteed by resorting to regeneration of the optical signal in intermediate nodes. Survivability is guaranteed by resorting to path protection. To exploit the sharing benefits, the scarce regenerators are used for both regeneration and wavelength conversion (WC) leading to a sharing of functionalities. Also, the shared path protection mechanism is exploited to ensure survivability against single-link failures and make the sharing of network resources (regenerators and wavelengths) possible. The paper presents a novel distributed scheme (DISTR) for reservation of regenerators and wavelengths in generalized multi-protocol label switching controlled WSONs, in order to ensure the required level of QoT and survivability. Novel objects and selection strategies for the resource reservation protocol with traffic engineering extensions are proposed and evaluated. The DISTR scheme effectively combines regeneration and WC points, leading to a noticeable reduction of the regeneration usage with respect to the existing schemes. Moreover, a significant reduction of the blocking probability is achieved, independently of the wavelength selection strategy used.

Label Preference Schemes for Lightpath Provisioning and Restoration in Distributed GMPLS Networks

In wavelength-routed networks based on a GMPLS control plane, the resource reservation protocol with traffic engineering extensions (RSVP-TE) allows to establish end-to-end lightpaths. The resource reservation can be blocked due to lack of available resources (forward blocking) or due to resource contentions (backward blocking). In wavelength-routed networks, the backward blocking is the predominant blocking contribution, when traffic load is low or highly-dynamic and when lightpath restoration takes place. To reduce the backward blocking, the paper proposes two label preference (LP) schemes compliant with RSVP-TE message exchanges. LP schemes provide the destination node with a label identifying the preferred wavelength to reserve. The preferred label is computed in a distributed way during the forward signaling phase, with the objective of assigning disjoint wavelengths to reservation attempts that may contend the resources. Simulation results demonstrate that, compared to other schemes, LP schemes are effective in reducing the backward blocking during both lightpath provisioning and restoration, without negatively impacting the forward blocking.

MICRON—A Framework for Connection Establishment in Optical Networks

Traffic grooming in optical networks has gained significance due to the prevailing sub-wavelength requirement of end users. Optical networks get upgraded to the latest technology slowly with time with only a subset of nodes being upgraded to the latest technology. The networks are thus comprised of nodes employing heterogeneous switching architectures. In this paper, we develop a framework called Methodology for Information Collection and Routing in Optical Networks (MICRON) for connection establishment in optical grooming networks with heterogeneous switching architectures. We illustrate with examples the information that may be collected from the links, and operators that may be used to obtain information along a path. The information can be used to select a path dynamically depending on the network status. We complete the MICRON framework by providing a generic channel assignment procedure that could be employed to implement different channel assignment schemes. Various routing and channel assignment algorithms can be developed from the proposed framework. The framework may be easily implemented with simple traffic engineering extensions to the already existing routing protocols in the wide-area networks.

Performance of new link state advertisement mechanisms in routing protocols with traffic engineering extensions

The prevalent use of best-effort topology driven IP routing protocols with shortest path calculations can often lead to serious imbalance of packet traffic distribution when least cost paths converge on the same set of links, leading to unacceptable delays or packet loss even in the presence of feasible paths over less utilized links. Recently proposed enhancements to common routing protocols are promising to overcome such shortcomings by providing the means to distribute link state information that is more pertinent to traffic engineering in routed networks. This article presents several key results on the performance of the recently proposed OSPF-TE, with particular emphasis on OSPF-TE protocol traffic overhead and the impact of new link state advertisement triggering mechanisms on traffic-engineered routing accuracy.

Extensions to MPLS Networking for Enhanced Multiplatform Multicasting Services

Abstract This paper addresses the required extensions to the MultiProtocol Label Switching (MPLS) [1] signaling protocols (i.e., Resource Reservation Protocol [2] with Traffic Engineering extensions (RSVP-TE) [3] and Label Distribution Protocol (LDP) [4]) to support effective MPLS network multicasting functionalities for various Internet protocol (IP) based multicasting routing algorithms, such as, Distance Vector Multicasting Routing Protocol (DVMRP), Multicast Extensions for Open Shortest Path First (MOSPF), Protocol Independent Multicast-Dense Mode (PIM-DM), Protocol Independent Multicast-Sparse Mode (PIM-SM), and Core Based Tree (CBT). The multicasting extensions for MPLS networking proposed in this paper will not only enable the MPLS networking layer to support full multicasting services corresponding to the IP based multicasting algorithms, but will also enable the traffic engineering (TE) advantages of MPLS to support the multicasting operations [1].

Dynamic routing of restorable bandwidth-guaranteed tunnels using aggregated network resource usage information

The paper presents new algorithms for dynamic routing of restorable bandwidth-guaranteed paths. We assume that connections are requested one-by-one and there is no prior knowledge of future arrivals. In order to guarantee restorability an alternate link (node) disjoint backup (restoration) path has to be determined, as well as an active path, when the connection is initiated. This joint on-line routing problem is particularly important in optical networks and in MPLS networks for dynamic provisioning of bandwidth-guaranteed or wavelength paths. A simple solution is to find two disjoint paths, but this results in excessive resource usage. Backup path bandwidth usage can be reduced by judicious sharing of backup paths amongst certain active paths while still maintaining restorability. The best sharing performance is achieved if the routing of every path in progress in the network is known to the routing algorithm at the time of a new path setup. We give a new integer programming formulation for this problem. Complete path routing knowledge is a reasonable assumption for a centralized routing algorithm, but is not often desirable, particularly when distributed routing is preferred. We show that a suitably developed algorithm which uses only aggregated information, and not per-path information, is able to perform almost as well as one using complete information. Disseminating this aggregate information is feasible using proposed traffic engineering extensions to routing protocols. We formulate the dynamic restorable bandwidth routing problem in this aggregate information scenario and develop efficient routing algorithms. The performance of our algorithm is close to the complete information bound.