Optical Networking

Rajiv Ramaswami, IBM

Scope and Audience

This tutorial is intended for engineers and scientists wishing to get an introduction to the emerging field of optical networks, from a practical as well as theoretical standpoint. For researchers working in this field, the tutorial will cover recent developments and testbeds and provide an overview of the problems to be solved to enable widespread deployment of optical networks.

Abstract

This tutorial describes architectures for a new generation of optical networks using wavelength division multiplexing (WDM) that exploit the bandwidth and protocol transparency properties of optical fiber. While there is a huge installed base of optical fiber today, only a miniscule fraction of its 25 THz of bandwidth is being utilized. This bandwidth can be tapped by WDM which uses multiple wavelengths (channels) to provide orders of magnitude increase in network capacity. These different wavelengths are independent of each other and may carry different kinds of data and use different bit rates and protocols. High-capacity WDM multiprotocol links are already a commercial reality today and prototype networks have been demonstrated. The tutorial will cover the current state of optical networking technology and speculate on where it is headed.

Outline

Overview. Motivation and capabilities of optical networks
Applications in
- point-to-point links
- crossconnect MANs and WANs
- packet-switched LANs.
Introduction to lightwave transmission
- Single-mode and multi-mode propagation
- Attenuation, dispersion and bandwidth
- Amplified vs. repeatered systems
- Direct and coherent detection
Multiplexing: WDM, TDM, SCM, CDM
Components:
- Fixed and tunable transmitters
- Receivers
- Tunable filters
- Optical amplifiers
- Optical switches and wavelength routers
- Wavelength converters
Broadcast and select networks
- Comparison of star and bus topologies
- Media-Access Protocols:
  - Random access
  - Reservation based
  - Support of multiple traffic classes
  - Performance evaluation and comparison
- Scheduling:
  - Relationship to satellite scheduling
  - Scheduling algorithms
Wavelength routing networks.
- Concepts
- Fixed routing
  - Results on permutation routing, routing with blocking
- Reconfigurable networks
  - Routing and wavelength assignment problems.
  - Performance bounds
  - Routing heuristics
- Network design
  - Design of rings and star networks
  - Logical (virtual) multihop topology design-link with ATM
- Network control and management
  - Distributed control protocols
  - Fault management
Practical systems
Experiments, demonstrations and field trials of optical networks
- Bellcore lambdanet, BT early experiments
- NTT 128 wavelength experiments
- IBM Rainbow
- AT&T MIT DEC testbed
- Bellcore Columbia testbed
- New ARPA efforts

Lecturer

Rajiv Ramaswami received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Madras, in 1986, and the M.S. and Ph.D. degrees in Electrical Engineering and Computer Science from the University of California, Berkeley in 1988 and 1990, respectively. He is the manager of the optical network systems group at the IBM T. J. Watson Research Center. His group does applied research and product development in the area of optical networks.

He currently serves as an Editor for the IEEE/ACM Transactions on Networking, as a Guest Editor for a special issue on optical networks of the IEEE Journal of Selected Areas in Communication and the IEEE/OSA Journal of Lightwave Technology, and as an Editor-At-Large for optical communication topics for the IEEE Communications Society.

Rajiv Ramaswami
IBM Research
30 Saw Mill River Rd.
Hawthorne, NY 10532
rajiv@watson.ibm.com
914-784-7356

Last modified: October 18, 1995