Segment Routing (SR) is a source routing paradigm that can significantly reduce the state that must be maintained in individual nodes in order to forward packets. SR involves defining segments in the network, computing the end-to-end route of a flow or packet as a sequence of segments and encoding the route in the packet header as a label stack, where each label is a Segment ID (SID) that identifies a segment. A network where a set of SIDs is used is known as an SR domain. SR is particularly suitable for Software-Defined Networks (SDNs) since the controller can compute the segment routes and configure them at the source of each flow within an SR domain. One type of SID is a Node SID where the Node ID of the tail node of a segment is used to identify the path to that node. When using Node SID, the number of SIDs that any given node must be aware of is |V |, the number of nodes in an SR Domain. However, for large networks, this might be more than the capacity of the forwarding table in a given node. In this paper, a method to partition the domain into subdomains is discussed and the reduction in the requirement for forwarding entries is studied. Experimentation with a test topology shows that a logarithmic reduction in the table size is possible by repeatedly applying this method. © 2019 IEEE.