LISP Overview...

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.

How Does LISP Solve the Problem?

The concept of a "location/ID separation" has been under study by the IETF and various universities and researchers for greater than 15 years. The concept of Locator/ID Separation has long been considered important to resolving the DFZ routing table scaling issues. By splitting the device identity, its Endpoint Identifier (EID), and the device location, its Routing Locator (RLOC), into two different namespaces, improvements in scalability of the routing system can be achieved through greater aggregation of RLOCs.

What else does LISP do?

LISP was initially conceived to address Internet DFZ scalability issues. However, once the functionality of splitting IP identity and location is available, many potential benefits are possible. Some of the important use cases being developed include:

* Low OpEx, BGP-free multihoming with site-based policy control (ingress tunnel engineering) Low OpEx multihoming with ingress traffic engineering (TE) capabilities provides control and management of the utilization of the ingress bandwidth that is being paid for. This is accomplished while eliminating the need for Border Gateway Protocol (BGP) peering with upstream service providers. This case also supports eliminating the need for site renumbering and the associated complexities and costs when changing service providers by decoupling site addressing from core addressing.

* Multi-Address-Family Support LISP supports IPv4 and IPv6, natively, identically (v4/v4, v4/v6, v6/v4, v6/v6). IPv6 Transition support provides inherent, day-one Address-Family agnostic flexibilities. Incorporating LISP into an IPv6 transition or coexistence strategy can both speed and simplify the initial rollout of IPv6 by taking advantage of the LISP mechanisms to encapsulate IPv6 host packets within IPv4 headers (or IPv4 host packets within IPv6 headers). Incorporating LISP into an IPv6 transition strategy has demonstrated quick deployment times, low deployment and operational costs, little or no need for additional equipment or modifications, and high user-satisfaction.

* High-Scale virtualization/VPN support, with or without encryption Virtualization/Multi-tenancy support provides the capability to segment traffic with minimal infrastructure impact, but with high scale and global scope. Control plane and data plane traffic are segmented by mapping VRFs to LISP "instance-id's," making this overlay solution highly flexible, highly scalable, and inherently low OpEx.

* Data Center Host Mobility "extending subnets" or "across subnets" Data Center VM-Mobility support provides location flexibility for IP endpoints within the data center network and across the Internet due to the servers’ identifiers (EIDs) being separated from their location (RLOC). By using Cisco LISP VM-Mobility, you can deploy IP endpoints such as virtual machines anywhere regardless of their IP addresses and can freely move them across data center racks and rows, to separate locations, and globally across organizations.

LISP is a simple, incremental, network-based implementation that is deployed primarily in network edge devices. It requires no changes to host stacks, DNS, or local network infrastructure, and little to no major changes to existing network infrastructures. You can learn more about LISP in this quick video.

LISP Open-Source LISP is also available as an open-source implementation through LISPmob.org. LISPmob runs on Linux, Android, and OpenWRT -- and supports router mode (xTR), Map-Server (MS), RTR and LISP Mobile Node (Android and Linux, check the App at Googe Play. You can also contribute to LISP by joining the LISPmob community. Subscribe through LISPmob.org!