The Locator/ID Separation Protocol (LISP) is a network architecture and protocol that separates the IPv4 or IPv6 addresses into two new namespaces: Endpoint Identifiers (EIDs) and Routing Locators (RLOCs).

  1. Endpoint Identifiers (EIDs): These are the addresses assigned to end-hosts. EIDs are used in the source and destination address fields of packets.

  2. Routing Locators (RLOCs): These are the addresses assigned to devices (primarily routers) that make up the global routing system. RLOCs are used by the underlying routing system to move packets between source and destination EIDs.

The idea behind LISP is to make the Internet routing architecture more scalable and flexible. As the Internet grew, the size of the global routing table also grew, making it more and more complex to manage and less efficient. LISP helps by separating the locator and identifier functions of IP addresses, which makes it easier to manage routing tables and helps reduce their size.

LISP also facilitates mobility and multi-homing, as an EID can be associated with multiple RLOCs, and these associations can be changed dynamically without affecting the EID. This is beneficial for mobile devices, which can change their RLOC as they move across different networks, while keeping the same EID.