Network security is designed around a strong security framework, available tools, and standardized protocols. In complex multi-vendor environments, standards-based security solutions can ensure interoperability and operational efficiencies in realizing end-to-end security. Network providers depend upon security information available to them to help plan, design and implement and maintain their networks in order to meet the security objectives. Standards-based systematic methodology and guidelines identify and address critical security challenges of network and information security. This supplement establishes guidelines for implementing system and network security with a focus on telecommunications networks. This supplement provides security guidelines for critical activities during the network life-cycle. These guidelines address four areas: 1) technical security policy, 2) asset identification, 3) threats, vulnerabilities and mitigations, and 4) security assessment. The guidelines and associated templates help in systematically addressing the security of networks.