Traditionally, intelligence has always been added mainly to the switching component of the telecommunications infrastructure. The other two components of a telecom network, access (local loops) and transmission (transport) have so far merely played the role of circuit termination and information carrier, respectively.
Biography
The enormous growth in transport technology in the optical domain and the increasing information-carrying capacity of optical media have exposed wavelength as the basic ingredient of the transport component. Similar to the switching paradigm where service logic reserves resources for each connection/call during setup and delivers the service to the end user, the promise of wavelength-based services has led the transport component to be treated more as a service platform/enabler. Many different approaches have been proposed to benefit the end user in terms of such transport services.
In the emerging next-generation transport networks, referred to as optical networks, dense wavelength-division multiplexing (DWDM)-based optical network elements like optical cross-connects (OXCs) and optical add-drop multiplexers (OADMs) will have full control of the wavelengths and knowledge of:
With such intelligence, these network elements could create self-connecting and self-regulating networks. Many services have been explored in terms of how they can be delivered intelligently by the optical network and provide bearer services to the end user.
The Feature Topic "Intelligence in Optical Networks" is well timed considering the planning and R&D efforts going on in the optical market in building intelligence in optical networks. The Feature Topic attempts to survey:
The term intelligence in optical networks could mean different things. The term encompasses transport infrastructure aspects (intelligent optical layer/transport plane), distributed intelligence that would reside in network elements (intelligent control plane), and network management capabilities (intelligent management plane).
According to some, it means to adapt IP-like routing/signaling capability for topology/route discovery and connection setup in the optical/transport infrastructure; others aim to offer a multiservice-capable and client-transparent transport infrastructure with different quality of service (QoS) and 50 ms synchronous optical network (SONET)-like protection/restoration support. For some, the need for intelligence is not limited to the core of the transport network, but is also at the access/metro segments since they have devices running at optical line rates that need on-demand optical layer availability in term of wavelengths.
A good collection of five articles in this Feature Topic tries to address different aspects of building intelligence in optical networks. The key aspects are:
The first article, by David Benjamin et al., sketches a services view of intelligent optical networks. It examines what kind of services needs to be enabled in so-called intelligent optical networks such as wavelength and bandwidth-managed services, optical virtual private networks (VPNs), and so on.
This article presents a network framework that will allow carriers to more readily develop, deploy, and manage these new optical services. This framework addresses the need for standards, service delivery, and control at the edge of the network, and a strong service management layer.
The second article, by Eve L. Varma et al., proposes the architecture of a service optical network (SON) to realize an intelligent optical core to support "on-demand" switched connections and service management over an optical transport network (OTN).
It describes the key network infrastructure and control element components of intelligent optical networking solutions. It envisions leveraging state-of-the-art transport infrastructure capabilities, in conjunction with a distributed control plane that supports the associated intelligence. The core networks may include OTN and/or SONET/synchronous digital hierarchy (SDH) transport infrastructure capabilities, depending on the services offered (i.e., wavelength-managed, bandwidth-managed) and required switching granularity. This article also focuses on the key architectural aspects of an OTN infrastructure, and an optical control plane based on evolving automatically switched transport network/generalized multiprotocol label switching (ASTN/GMPLS) standards that supports realization of intelligent optical networking in core networks.
The third article, by Chunsheng Xin et al., focuses on the design and implementation aspects of an optical control plane. It describes how IP protocols could be adapted in the optical control plane as multiprotocol lambda switching (MP*S), Resource Reservation Protocol with Traffic Engineering (RSVP-TE), and Constraint-Routed Label Distribution Protocol (CR-LDP) to add intelligence in transport networks. With intelligence of the control plane, OXCs would behave as intelligent network-level devices like routers in an IP network rather than as dumb physical layer devices. This article augments the ongoing similar research efforts on introducing intelligence into optical networks.
The fourth article, by A. McGuire et al., examines how intelligence can be distributed between the management and control planes. It describes the differences between soft permanent connections, where setup and teardown are initiated by the management system, and switched connections supervised by the control plane.
It also highlights the major features required by the control plane and projects that this would largely depend on the type of connection offered, whether it is vertically integrated (management controlled) or bears a peer relationship (distributed control), and the ability offered to the end user to manage the connection (bandwidth).
The article suggests that a control plane may well be more beneficial for networks with large volumes of low-bandwidth connections, rather than those with a relatively small number of high-bandwidth connections. It also proposes the need to complement the control plane with service management capabilities for effective operation support systems (OSSs).
The fifth and last article, by Hui Zang et al., discusses the implementation aspects of establishing a lightpath, an all-optical connection in wavelength-Routed WDM networks. It reviews routing and wavelength assignment (RWA), signaling, and resource reservation as the control mechanisms to set up connections intelligently. Two control protocols, one based on link-state routing and another based on distance-vector routing, are described in detail
The editor acknowledges and thanks the authors for their time in making timely contributions on a topic that is still going through active research and field trials. The author also thanks all the reviewers for their time and valuable comments.
Anant Kumar Jain [SM] has been a member of technical staff at Lucent Technologies since 1997. He is a systems engineer in operations systems in the Optical Networking Group. He has an M.B.A. degree from Northeastern University, Boston, Massachusetts. He holds an M.E. in electrical communications engineering from the Indian Institute of Science, Bangalore (topped with distinction) and a B.Sc. (honors) in chemistry from Hindu College, University of Delhi, India. Prior to joining Lucent, he was a consultant for 10 years, working for clients such as Lucent, IBM, Nortel, and Harris Corporation, and was the project leader on various projects, especially Interface Approval of Nortel's Switch in India. He is very active in ComSoc. He was Chair of the Boston Chapter, 19992000; in 1999 the Boston Chapter was given the Chapter of the Year Award, and he wrote an invited article on the Boston Chapter in the July 2000 issue of IEEE Communications Magazine. He served as General Chair, IEEE Intelligent Networks Workshop 2001, which was held in Boston 69 May 2001 (http://www.comsoc.org/IN2001). He was also Co-Chair, Optical Networking Track, IEEE Electro/Nepcon East 2000, held in Boston in June 2000. He represents ComSoc on IEEE Standards Coordinating Committee 36 (SCC36) on the Utility Communication Industry. He has been selected as Accreditation Board of Engineering and Technology/Technology Accreditation Commission (ABET/TAC) Program Evaluator, a program supported and endorsed by IEEE Educational Activities Board. He serves on the Technical Program Committees of various international conferences such as IWAN 2000 and IEEE OpenArch '02, and serves as a reviewer for many magazines of international repute. His research interests include OSI and IP protocols, network management, optical networking, intelligent networks, active networks, programmable networks, and interprocess communications. He has written a white paper on "Intelligent Multiservice Networks."