IP over Optical Networks: A Framework 

Source: IETF  draft-ietf-ipo-framework-00.txt -  Expires on: 1/13/2002

This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress."

Table of Contents ----------------- 1

Abstract........................................................1

2. Conventions used in this document...............................3 

3. Introduction....................................................3 

4. Terminology and Concepts........................................4

5. The Network Model...............................................8

5.1 Network Interconnection.....................................8

5.2 Control Structure..........................................10

6. IP over Optical Service Models and Requirements................12

6.1 Domain Services Model......................................12

6.2 Unified Service Model......................................13

6.3 Which Service Model?.......................................14 

6.4 What are the Possible Services?.............................14 

7. IP transport over Optical Networks.............................15 

7.1 Interconnection Models......................................15 

7.2 Routing Approaches..........................................16 

7.3 Signaling-Related...........................................19 

8. IP-based Optical Control Plane Issues..........................22 

8.1 Addressing.................................................23 

8.2 Neighbor Discovery.........................................24 

8.3 Topology Discovery.........................................25 

8.4 Restoration Models.........................................26 

8.5 Route Computation..........................................27 

8.6 Signaling Issues...........................................29 

8.7 Optical Internetworking...................................31 

9. Other Issues...................................................32 

9.1 WDM and TDM in the Same Network...........................32 

9.2 Wavelength Conversion.....................................32 

9.3 Service Provider Peering Points...........................32 

9.4 Rate of Lightpath Set-Up..................................33 

9.5 Distributed vs. Centralized Provisioning..................34 

9.6 Optical Networks with Additional Configurable Components..34 

9.7 Optical Networks with Limited Wavelength Conversion Capability......................................................34 

10. Evolution Path for IP over Optical Architecture..............35 

11. Security Considerations.......................................36 

12. Summary and Conclusions.......................................36 

13. References....................................................36 

14. Acknowledgments...............................................38 

15. Author's Addresses............................................38

Abstract 

The Internet transport infrastructure is moving towards a model of high-speed routers interconnected by optical core networks. The architectural choices for the interaction between IP and optical network layers, specifically, the routing and signaling aspects, are maturing. At the same time, a consensus has emerged in the industry on utilizing IP-based protocols for the optical control plane. This draft defines a framework for IP over Optical networks, considering both the IP-based control plane for optical networks as well as IP- optical network interactions (together referred to as "IP over optical networks").

Introduction:

Optical network technologies are evolving rapidly in terms of functions and capabilities. The increasing importance of optical networks is evidenced by the copious amount of attention focused on IP over optical networks and related photonic and electronic interworking issues by all the major network service providers, telecommunications equipment vendors, and standards organizations. In this regard, the term "optical network" is used generically in practice to refer to both SONET/SDH-based transport networks, as well as transparent all-optical networks. It has been realized that optical networks must be survivable, flexible, and controllable. 

There is, therefore, an ongoing trend to introduce intelligence in the control plane of optical networks to make them more versatile [1]. An essential attribute of intelligent optical networks is the capability to instantiate and route optical layer connections in real-time or near real-time, and to provide capabilities that enhance network survivability. Furthermore, there is a need for multi-vendor optical network interoperability, when an optical network may consist of interconnected vendor-specific optical sub-networks. 

The optical network must also be versatile because some service providers may offer generic optical layer services that may not be client-specific. It would therefore be necessary to have an optical network control layer that can handle such generic optical services. There is general consensus in the industry that the optical network control plane should utilize IP-based protocols for dynamic provisioning and restoration of light paths within and across optical sub-networks. This is based on the practical view that signaling and routing mechanisms developed for IP traffic engineering applications could be re-used in optical networks. Nevertheless, the issues and requirements that are specific to optical networking must be understood to suitably adopt the IP-based protocols. This is especially the case for restoration. Also, there are different views on the model for interaction between the optical network and client networks, such as IP networks. Reasonable architectural alternatives in this regard must be supported, with an understanding of their pros and cons.  

Thus, there are two fundamental issues related to IP over optical networks. The first is the adaptation and reuse of IP control plane protocols within the optical network control plane, irrespective of the types of digital clients that utilize the optical network. The second is the transport of IP traffic through an optical network together with the control and coordination issues that arise there from.

For more information on this article, please write to:

moreipo@infomatek.com

Click below for more developments and tutorial articles:

[ Home ] [ Orthogonal Frequency Division Multiplexing ]

Send mail to webmaster@infomatek.com with questions or comments about this web site.
Copyright © 2001 Infomatek Consulting and Marketing Services