MERLiN

One such challenge is the development of standardized architectures and protocols for network and optical layers, appropriate at very high speeds, and for different environments (e.g., local access/metro and long haul). While experimentation on DARPA sponsored testbed will reveal useful field information about these issues, a simulation tool which can provide rapid and accurate analysis is now essential for timely resolution of the challenges of the integration of networking and optical layers. Building such a network evaluation tool with a high degree of link and optical layer detail (which is required at high speeds such as in excess of OC-48, for DWDM, and for low BER) is now feasible using physical device/component modeling and simulation tools that are under development or commercially available.

Second, a variety of optical networks (based on SONET, WDM, and perhaps TDM) will coexist with legacy networks in the next generation infrastructure. Accordingly, NGI network engineering tools must incorporate existing and emerging optical networking technologies, which have many design features different from those of conventional networks. For example, the distinction between virtual and physical topology designs is made in WDM networks. Network engineering issues also include design at different time scales: from capacity provisioning to handle traffic growth done on a scale of months, to split-second dynamic reconfiguration, with attendant packet/connection management, as an efficient response to fast traffic changes and mission critical applications. Additionally, multiple services with QoS differentiation must be optimally mapped to light-paths, and parameters of protection/restoration functions at optical and electronic layers must be engineered to avoid destructive interference. Furthermore, the accuracy of such tools is enhanced by incorporating optical network management and control functions either via models or by interfacing with actual management and control objects.

The High Speed Network Technologies group in the Advanced Networking Technologies proposes to develop an optical network modeling and planning tool (MERLiN), which is:

1) capable of rapid evaluation of protocols and architectures, with respect to their characteristics in different environments; and 2) also a network engineering tool that can inter-work with higher layer models, and device level simulators.

Modeling Evaluation and Research of Lightwave Network (MERLiN) is a Wavelength Division Multiplexing (WDM) network design and modeling environment that is currently under development at the National Institute of Standards and Technology. The main purpose for this tool is to allow the development and evaluation of algorithms for wavelength assignment, routing, dynamic reconfiguration and restoration mechanisms without the expense of building a real network. There are two major uses for MERLiN: as a tool for WDM network planning and as a tool for WDM protocol performance analysis.

As a planning tool, a network planner can run the simulator with various network configurations, traffic loads to obtain statistics such as wavelength utilization, throughput rates, blocking probabilities. It could be used to answer questions such as: what is shortest path between two nodes, how many wavelengths are utilized on a path, will adding a new connection cause congestion. Statistics and routes are displayed directly on the screen or could be logged in a data file for further processing.

As a protocol analysis tool, a researcher or protocol designer could study the total system effect of particular prototcol. For example, one could investigate the effectiveness of various reconfiguration algorithms for WDM networks and address such issues as: mechanisms for dynamic provisioning, protocol overhead, throughput. MERLiN can be easily extended to implement additional optical network control and management procedures such as performance monitoring, quality of optical service provisioning, and fault detection and recovery.

• The MERLiN Software, Version 1.1, Request Form (as of Aug15,2001)

• MERLiN, User's Manual and Programmer's Guide, Version 1.0, February 2000

For inquiries regarding this project, contact Oliver Borchert.