Optical Switching and Networking 6 (2009) 268–275 Contents lists available at ScienceDirect Optical Switching and Networking journal homepage: www.elsevier.com/locate/osn A concurrent two-layer restoration scheme for GMPLS WDM networks ✩ Rabindra Ghimire a , Seshadri Mohan b,* , Michael Leary c , Terry Tidwell c a Applied Science Department, University of Arkansas at Little Rock, Little Rock, AR 72204, United States b Systems Engineering Department, University of Arkansas at Little Rock, Little Rock, AR 72204, United States c Space Photonics, Inc., 700 Research Center Blvd., Fayetteville, AR 72701, United States article info Article history: Received 1 June 2009 Received in revised form 3 August 2009 Accepted 27 August 2009 Available online 4 September 2009 Keywords: GMPLS Multilayer restoration Optical network Survivability Wavelength routing WDM abstract Next generation backbone networks will likely consist of IP routers as well as optical cross connects (OXCs) and will deploy an optical control plane protocol. Generalized Multi Protocol Label Switching (GMPLS) has been proposed as the candidate of choice for the control plane. Optical fibers may carry large volumes of traffic and therefore adequate mechanisms must exist to enable the network to automatically recover from failures of fiber. In mission critical networks survivability becomes very important. We investigate the problem of autonomous recovery in such networks. The literature contains work in this area that investigates the problem of multilayer recovery. Such recovery had only been sequential in the sense that the published work recovers first in the optical domain, assuming the availability of redundant resources, and then proceeds to recover packet label switched paths. We report a recovery procedure for recovering packet label switch paths (packet LSPs) and lambda label switch paths (λLSP) concurrently. We have conducted an OPNET-based simulation study that compares the performance of the concurrent scheme with the previously published sequential two-layer recovery scheme. The study shows that the concurrent two-layer recovery scheme performs as much as forty-four percent faster than the sequential two-layer recovery scheme. © 2009 Elsevier B.V. All rights reserved. 1. Introduction With the explosive growth in internet traffic, the next generation backbone networks will likely consist of IP routers as well as optical cross connects (OXCs), hereafter referred to as photonic GMPLS router [1]. The network will have the capability to perform packet switching together with wavelength path switching in order to provide quality of service (QoS). Wavelength division multiplexing (WDM) and dense wavelength division multiplexing (DWDM) technologies are playing a dominant role in providing high bandwidth optical transport. GMPLS has emerged as the ✩ The research work was carried out in partnership with Space Photonics, Inc., and supported in part by the NSF Grant: EPS-0701890. * Corresponding author. Tel.: +1 501 683 7475. E-mail addresses: rxghimire@ualr.edu (R. Ghimire), sxmohan@ualr.edu (S. Mohan). leading control plane protocol for optical networks and utilizes the color of wavelengths as labels to establish lightpaths, referred to as lambda label switched path (λLSP) [2]. GMPLS controls both the establishment of packet label switched paths (packet LSPs) and λLSPs. In this paper, we refer to the λLSPs as the optical plane and the packet LSPs as the MPLS plane. Photonic GMPLS routers use GMPLS as the control plane protocol. The primary components of the GMPLS protocol engine include an OSPF-TE extension module, Path Com- putation Elements (PCE) and a Resource Reservation Pro- tocol module with traffic engineering (RSVP-TE). In order to provision or restore a connection, a route and a wave- length (label) must be identified for each connection. The OSPF-TE protocol distributes link state information, and determines a route for the connection; the RSVP-TE pro- tocol reserves the necessary resources along the identified route. Consider the case in which GMPLS routers generate 1573-4277/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.osn.2009.08.005