Huawei Huawei Huawei An IGP Flexible Algorithm (Flex-Algorithm) allows IGPs to compute constraint-based paths. IGP Flex-Algorithm can be used with Segment Routing (SR) or IP data plane. When used with SR data plane, Flex- Algorithm requires to allocate algorithm specific Prefix Segment Identifiers (SIDs) or algorithm specific SRv6 Locators. When used with IP data plane, Flex-Algorithm requires to allocate algorithm specfic IPv4 or IPv6 prefixes. This increases the complexity and overhead of managing, advertising and maintaining additional SR SIDs, SRv6 Locators and IPv4 or IPv6 prefixes, which may not be affordable to some networks and network devices. This document extends IGP Flex-Algorithm to allow the use of common SR SIDs, SRv6 Locators and IP prefixes among multiple Flex- Algorithms.