The Survivable Network Design Library (SNDlib) is a data library for fixed telecommunication network design, accessible at http://sndlib.zib.de. Version 1.0 of SNDlib contains data related to 22 networks, resulting in 830 network planning problem instances. The library provides a mathematical model for each planning problem and describes the data concepts. It includes statistical information and details about the origin of the data sets. SNDlib aims to become a standard for testing and demonstrating the effectiveness of new optimization models and algorithms in network design. The library is structured into two parts: an SNDlib network instance, which describes nodes, links, demands, and capacities, and an SNDlib model instance, which specifies design parameters such as demand and link models, capacity models, and survivability concepts. The paper also presents a mathematical reference model for the SNDlib problems, including constraints and objective functions. The 22 networks in SNDlib have diverse backgrounds, including industrial projects, international research projects, and other sources, covering a wide range of problem sizes and complexities. SNDlib also provides a platform for sharing additional information, such as bibliography entries, conference lists, and a mailing list.The Survivable Network Design Library (SNDlib) is a data library for fixed telecommunication network design, accessible at http://sndlib.zib.de. Version 1.0 of SNDlib contains data related to 22 networks, resulting in 830 network planning problem instances. The library provides a mathematical model for each planning problem and describes the data concepts. It includes statistical information and details about the origin of the data sets. SNDlib aims to become a standard for testing and demonstrating the effectiveness of new optimization models and algorithms in network design. The library is structured into two parts: an SNDlib network instance, which describes nodes, links, demands, and capacities, and an SNDlib model instance, which specifies design parameters such as demand and link models, capacity models, and survivability concepts. The paper also presents a mathematical reference model for the SNDlib problems, including constraints and objective functions. The 22 networks in SNDlib have diverse backgrounds, including industrial projects, international research projects, and other sources, covering a wide range of problem sizes and complexities. SNDlib also provides a platform for sharing additional information, such as bibliography entries, conference lists, and a mailing list.