Techniques and mechanisms for compressing the size of SIDs to be smaller than a complete IPv6 address (or “micro SIDs”), and scaling micro SIDs across a multi-domain environment using micro SID-domain-blocks. Segment routing over IPv6 (SRv6) uses 128-bit IPv6 addresses as SIDs for segment routing. According to this disclosure, multiple SRv6 SIDs may be expressed in a compact format such that a 128-bit IPv6 address, such as the destination address field of the IPv6 header, may store multiple micro SIDs. Further, SID-domain-blocks may be assigned to each domain in a multi-domain network such that micro SIDs may be expressed in the context of a given domain, rather than being shared in the global multi-domain network. In this way, lists of domain-specific SIDs may be fully expressed in the IPv6 destination address of the packet to scale micro SID into large, multi-domain networks.