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Global Standardization Activities

Standardization of IP and Optical Networking Technologies

Ichiro Inoue, Eiji Oki, Tomonori Takeda, Kohei Shiomoto, and Wataru Imajuku


Internet protocol (IP) and optical networking technologies based on generalized multiprotocol label switching (GMPLS), path computation element (PCE), and layer-1 virtual private network (L1VPN) enable unified control and management of future backbone network layers that will be able to cope with unexpected situations such as drastic changes in demand and multiple failures effectively and quickly according to an operator's policy and that will let us create new network services. This article describes the latest standardization of IP and optical networking technologies in IETF (Internet Engineering Task Force) and ITU-T (International Telecommunication Union, Telecommunication Standardization Sector).

NTT Network Service Systems Laboratories
Musashino-shi, 180-8585 Japan

1. Importance of IP and optical networking technology standardization

The backbone networks are currently experiencing great changes, more than ever before, in traffic demand with the wider penetration of broadband access and appearance of unforeseen new applications, but service quality is degraded if there are failures and the impact is heavier than before. Future backbone network should be capable of (1) controlling and managing multiple layers, (2) coping with unexpected situations quickly, (3) applying the operator's policy, (4) providing rate- and format-free flexibility, and (5) providing on-demand services [1].

ITU-T (International Telecommunication Union, Telecommunication Standardization Sector) has been working very hard on NGN (Next Generation Network) standardization to enable various applications over managed packet networks. IETF (Internet Engineering Task Force), on the other hand, has been standardizing Internet protocol (IP) and multiprotocol label switching (MPLS) as de facto technologies, which are now international standard technologies recognized within ITU-T. IETF has been aggressively working on the standardization of IP and optical networking technologies such as generalized multiprotocol label switching (GMPLS), unified optical and IP network architectures (multilayer and multiregional network architectures, and MPLS and GMPLS interworking), flexible and complicated traffic engineering according to operator policy (path computation element (PCE)), and layer-1 virtual private network (L1VPN), which provides protocol-free layer-1 paths on demand. An overview of standardization areas for IP and optical networking technologies is shown in Fig. 1.

Fig. 1. Standardization areas for IP and optical networking technologies.

2. GMPLS standardization

GMPLS generalizes the label concept of MPLS, which identifies a packet layer data flow, so that the label can be applied to data flows of other layers such as layer-1 connections. Other GMPLS label examples include time slot, wavelength, physical port for fiber, and even packet flow like MPLS labels (see Fig. 2).

Fig. 2. GMPLS label applications.

The basic set of protocols including extensions of RSVP (resource reservation protocol), OSPF (open shortest path first), and LMP (link management protocol) have been standardized reflecting interoperability test results in the IETF common control and measurement plane (CCAMP) [2] working group (WG). The scope of CCAMP WG is shown in Fig. 3. This WG is mainly discussing GMPLS applications.

Fig. 3. Scope of the CCAMP WG.

The first application of GMPLS is interworking between MPLS and GMPLS and migration from MPLS to GMPLS, where routing and signaling interoperability and migration framework and requirements have now reached the stage of being request for comments (RFC).

The second application is GMPLS-based network architectures where requirements and analytical results of existing GMPLS protocols are now stable and expected protocol extensions are being WG draft status.

The third application is technology- and implementation-specific aspects including control transition of a path from an operating system provision basis to a GMPLS basis (semipermanent connection to switched connection), protocol extension for Ethernet switching capability, and extensions specific to all-optical networks including reconfigurable optical add/drop multiplexers (ROADMs), which are now being deployed worldwide.

IETF and ITU-T have recently been collaborating on GMPLS, where GMPLS applicability to the ITU-T-based transmission network architecture called ASON (automatically switched optical network), and the next generation time-division multiplexing transmission technologies such as LCAS (link capacity adjustment scheme) and VCAT (virtual concatenation).

3. PCE standardization

PCE (path computation element) [3] is a route calculating element that is functionally decoupled from network elements such as routers and switches in which the calculating function was traditionally embedded. The decoupling of the function enables multidomain and multilayer traffic engineering and lowers the burden of calculation scalability and complexity. IETF established the PCE WG based on proposals from NTT and other members in 2005. The basic set of protocols and architectures is stable and nine PCE protocol implementations have been reported, as of December 2007.

Current discussion of enhancements includes, firstly, protocol extensions targeting interdomain and interlayer calculation, global optimization where multiple paths are simultaneously optimized, excluding specific nodes, and VPN multicasting. These extensions are expected to be standardized soon after the basic protocol standardization has been finalized around the first half of 2008.

The second discussion area includes technologies for PCE to be managed and operated in real networks. Some examples are a PCE discovery protocol, PCE performance monitoring protocol, and new architecture for incorporating network policy into PCE calculations.

ITU-T already has an international standard for PCE in the context of ASON, which is G.7715.2. Refer to Fig. 4 for the detailed scope of the PCE WG.

Fig. 4. Scope of PCE WG.

4. L1VPN standardization

L1VPN [4] provides virtually dedicated layer-1 network resources to each customer. It is being standardized in IETF's L1VPN WG, which was established after proposals by NTT and other members in 2005.

The framework is already standardized: it defines three L1VPN modes. Protocols related to the basic mode (i.e., signaling and discovery) have passed through the working group level last call. Currently, the most advanced enhanced mode is being worked on through detailed analysis and applicability evaluation of GMPLS protocols for achieving the enhanced mode. ITU-T has already established L1VPN basic international standards based on NTT proposals. Details of the scope of the L1VPN WG are given in Fig. 5.

Fig. 5. Scope of L1VPN WG.

5. Conclusion

In addition to producing the next-generation network services and technologies, in order to cope with unexpected situations effectively and provide new competitive services quickly, IP and optical networking technologies are expected to play a fundamental role in future telecommunications. IETF and ITU-T have been standardizing GMPLS and other IP and optical networking technologies and NTT has contributed in terms of both technology and management. NTT had contributed 18 major IETF specifications as editor, first author, or coauthors, as of January 2008 (Fig. 6). NTT also provided Japan's second WG chairperson in the area. Recently, other Japanese providers and research institutes have been becoming active and contributing many technical proposals. NTT will continue to contribute to the maturing of technology in both standardization and deployment.

Fig. 6. IETF standardization process.


[1] Special Feature on The Future of IP and Optical Networking, NTT Technical Review, Vol. 5, No. 3, pp. 48–71 Mar. 2007.
Ichiro Inoue
Senior Research Engineer, Supervisor, Backbone Networking Systems Group, Broadband Network Systems Project, NTT Network Service Systems Laboratories.
He received the B.E and M.E. degrees in electrical engineering from the University of Tokyo, Tokyo, in 1988 and 1990, respectively. He joined NTT in 1990. Since then, his research interests have included telecommunication protocols such as IP and ATM. He was engaged in research and international standardization of the ATM adaptation layer protocol for data and control plane applications over ATM networks. He joined the xbind program investigating end-to-end high-level network service virtualization technologies as a Visiting Scholar at Columbia University, NY, USA, from 1995 to 1996. After that, he became a technical manager responsible for an audio-visual conferencing network architecture and its trial and commercial service at an NTT division. After returning to NTT Network Service Systems Laboratories, he conducted many R&D projects for broadband IP core and edge routers and networking. In 2001, he began researching international standardization of IP and optical networking technologies such as a multilayer service network architecture and layer-1 VPN. He has been active in standardization such as ISO/ISC (as a national committee member), ITU-T, and IETF. He is a member of IEEE and the Institute of Electronics, Information and Communication Engineers (IEICE) of Japan. Since 2007, he has been a Secretary of the IEICE Communication Society's Technical Committee on Network Systems.
Eiji Oki
Senior Research Engineer, Backbone Networking Systems Group, Broadband Network Systems Project, NTT Network Service Systems Laboratories.
He received the B.E. and M.E. degrees in instrumentation engineering and the Ph.D. degree in electrical engineering from Keio University, Kanagawa, in 1991, 1993, and 1999, respectively. He joined NTT Communication Switching Laboratories in 1993. Since then, he has been researching multimedia-communication network architectures based on ATM techniques, traffic-control methods, and high-speed switching systems. From 2000 to 2001, he was a Visiting Scholar at Polytechnic University, Brooklyn, New York, where he was involved in designing terabit switch/router systems. He is now engaged in R&D of high-speed optical IP backbone networks. He received the 1998 Switching System Research Award and the 1999 Excellent Paper Award from IEICE, and the 2001 Asia-Pacific Outstanding Young Researcher Award presented by IEEE Communications Society for his contribution to broadband network, ATM, and optical IP technologies. He co-authored “Broadband Packet Switching Technologies,” published by John Wiley, New York, in 2001 and “GMPLS Technologies,” published by CRC Press, Boca Raton, in 2005. He is a Senior Member of IEEE and a member of IEICE.
Tomonori Takeda
Engineer, Backbone Networking Systems Group, Broadband Network Systems Project, NTT Network Service Systems Laboratories.
He received the M.E. degree in electronics, information and communication engineering from Waseda University, Tokyo, in 2001. He joined NTT in 2001 and has been engaged in research on the next-generation network architecture, IP optical network architecture, and related protocols. He currently co-chairs the L1VPN WG in IETF. He is a member of IEEE and IEICE.
Kohei Shiomoto
Senior Research Engineer, Supervisor, Group Leader, Backbone Networking Systems Group, Broadband Network Systems Project, NTT Network Service Systems Laboratories.
He received the B.E., M.E., and Ph.D. degrees in information and computer sciences from Osaka University, Osaka, in 1987, 1989, and 1998, respectively. He joined NTT in 1989 and engaged in R&D of ATM traffic control and ATM switching system architecture design. During 1996–1997, he was engaged in research on high-speed networking as a Visiting Scholar at Washington University in St. Louis, MO, USA. During 1997–2001, he was directing architecture design for the high-speed IP/MPLS label switching router research project at NTT Network Service Systems Laboratories. Since July 2001, he has been engaged in the research fields of photonic IP router design and routing algorithms and in GMPLS routing and signaling standardization, first at NTT Network Innovation Laboratories and then at NTT Network Service Systems Laboratories. He is active in GMPLS standardization in IETF. He is a member of IEEE, IEICE, and the Association for Computing Machinery. He was the Secretary for International Relations of the Communications Society of IEICE from June 2003 to May 2005. He was the Vice Chair of Information Services of the IEEE ComSoc Asia Pacific Board from January 2004 to December 2005. He has been involved in the organization of several international conferences including HPSR 2002, WTC 2002, HPSR 2004, WTC 2004, MPLS 2004, iPOP 2005, MPLS 2005, iPOP 2006, and MPLS 2006. He received the Young Engineer Award from IEICE in 1995 and the Switching System Research Award from IEICE in 1995 and 2000. He is one of the authors of “GMPLS Technologies: Broadband Backbone Networks and Systems”.
Wataru Imajuku
Senior Research Engineer, NTT Network Innovation Laboratories.
Since joining NTT Laboratories in 1994, he has been engaged in R&D activities related to optical amplifiers, high-speed photonic transmission, and photonic IP networking. He led the development project on GMPLS in NTT Laboratories, authored and co-authored more than 70 publications, and holds about 30 patents in his research field.