LISP - what is it

With traditional IP routing, an IP address has two functions:

  • Identity: To identify the device.
  • Location: The location of the device in the network; we use this for routing.

The Locator Identity Separation Protocol (LISP) separates these two functions of an IP address into two separate functions:

  • Endpoint Identifier (EID): Assigned to hosts like computers, laptops, printers, etc.
  • Routing Locators (RLOC): Assigned to routers. We use the RLOC address to reach EIDs.

Cisco created LISP, but it’s not a proprietary solution, it’s an open standard. Originally it was designed for the Internet, but nowadays, you also see LISP in other environments like data centers, IoT, WAN, and the campus (Cisco SD-Access).

Splitting EID and RLOC functions yields many benefits, including simplified and cost-effective multi-homing, ingress Traffic Engineering (TE) capabilities, IP address and host mobility, including session persistency across mobility event, IPv6 transition simplification, including incremental deployment of IPv6 using existing IPv4 infrastructure, and simplified, highly-scalable network virtualization.