The traditional IP addressing model associates both Location and Identity to a single IP address space, making mobility a very cumbersome process since identity and location are tightly bundled together. Because LISP creates two separate name spaces, separating IP addresses into Route Locators (RLOC) and End-point Identifiers (EID), and provides a dynamic mapping mechanism between these two address families, EIDs can be found at different RLOCs based on the EID-RLOC mappings. RLOCs remain associated with the topology and are reachable by traditional routing. However, EIDs can change locations dynamically and are reachable via different RLOCs, depending on where an EID attaches to the network. In a virtualized data center deployment, EIDs can be directly assigned to Virtual Machines that are hence free to migrate between data center sites preserving their IP addressing information.

The decoupling of Identity from the topology is the core principle on which the LISP Host Mobility solution is based. It allows the End-point Identifier space to be mobile without impacting the routing that interconnects the Locator IP space. When a move is detected, the mappings between EIDs and RLOCs are updated by the new xTR. By updating the RLOC-to-EID mappings, traffic is redirected to the new locations without requiring the injection of host-routes or causing any churn in the underlying routing.