Cost/survivability analysis of multi-layer restoration strategies in broadband transport networks

Service survivability, i.e., continued service provision amidst network facility failures is an important feature of broadband transport networks. Due to the multitechnology (e.g., IP, ATM, SONET, WDM) and multiservice (e.g., low delay, low loss, etc.) aspects of the present day broadband transport networks, multi-layer restoration strategies that take advantage of the particular networking technology and the restoration objectives of the particular service will be very useful. However, with the potential advantages of multi-layer restoration are a variety of tradeoffs. Thus, a systematic methodology that can help analyze the cost-survivability performance tradeoffs is essential to a good network engineering and design. We propose a methodology that can be used to analyze the cost/survivability performance tradeoffs of single- and multi-layer restoration strategies. We also use the proposed methodology to analyze the performance of a multi-layer restoration strategy for ATM-SONET networks, and compare the performance of the proposed multi-layer restoration strategy with single-layer strategies such as the single-layer SONET 1:1 APS, ATM switch-based restoration strategies and the popularly used self-healing bi-directional line switched rings (BLSRs).