Locator/ID Separation Protocol LISP
LISP is a network architecture and set of protocols that implements a new semantic for IP addressing. LISP creates two namespaces and uses two IP addresses: Endpoint Identifiers (EIDs), which are assigned to end-hosts, and Routing Locators (RLOCs), which are assigned to devices (primarily routers) that make up the global routing system.
What's the Problem?
Traditional Internet routing and addressing architectures use a single namespace, the IP address, to simultaneously express two functions about a device: its identity, and its location within the network. The often-quoted "Yakov's Law" states [“Addressing can follow topology or topology can follow addressing; choose one” – Y. Rekhter]. A very visible and detrimental effect of this single namespace is manifested in the rapid growth of the Internet's DFZ (default-free zone) as a consequence of multihoming, traffic engineering, non-aggregatable address allocations, and business events such as mergers and acquisitions. The Internet Architecture Board's October 2006 Routing and Addressing Workshop recogized that the negatvie effects of the growth of the Internet routing table, as documented in RFC 4984, and initiating invesitgations of ID/locator separation options. Prior to LISP, the concepts of separating the locator and the identifier has been discussed for many years as a way to greatly reduce the size of the Internet DFZ. The protocol known as LISP comprises the development of specifications for the IETF. For routing to scale, locators need to be assigned according to topology and change as topology changes. LISP accomplishes this by adding the level of indirection between host IPs and Locator IPs.
This problem has been further exacerbated by two further conditions. The first is IPv4 address space depletion which has led to a finer breakup of IPv4 addresses with less aggregation potential, especially in the case of Provider Independent (PI) addressing. The second is the increasing occurance of dual-stack routers supporting both IPv4 and IPv6 protocols. IPv6 did not change anything about the use of IP addresses (no inherent locator separation) and so it suffers from the same problems as IPv4 - only with larger addresses.
From a Customer perspective, they face significant challenges in many aspects of operating their networks. Some of the more important areas of concern include:
* the complexity of todays networks, especially when multi-homing is required for increased bandwidth and availability and for resiliency. Often times a network staff with a "PhD in BGP" is required to support routine operations.
* the complexities and expenses associated with site re-numbering when changing services providers inhibits competition, and is detrimental to the development of new services.