What would you say if I told you that one of the most visited websites on the Internet enabled IPv6 connectivity to their site in the course of an afternoon for zero dollars using existing Cisco hardware? How about if I told you that the site was Facebook? Most people would assume I was joking or exaggerating. However, by using LISP, Cisco Certified Internetworking Expert Donn Lee pulled off this seemingly impossible feat and then presented a paper at the North American Network Operators Group (NANOG) about the experience. You can even watch the video here.
What is LISP?
Let’s start by understanding the problem that LISP solves. An IP address serves two distinct functions: It identifies the endpoint host, but also suggests the location because the high order bits identify the network on which the device is located. If you move a device from one subnet to another, the address has to change since the device location changes. The endpoint identification from the previous location gets lost when the device moves, unless some form of tunneling or mobility protocol is employed.
LISP introduces a distributed database which maps IP addressed endpoints (EIDs) to so-called route locators (RLOCs) in a way which is invisible to the endpoints. The routing elements of the LISP network identify each other and the endpoints they serve in such a way that the address of the endpoint becomes nothing more than an identifier of the host. The RLOCs pass information and traffic among each so that endpoints can use this overlaid network infrastructure transparently, without any host-side changes. A side effect of separating the routing and identification elements of a device is that address family traversal becomes a trivial matter.
Here’s the short version: Using only a LISP capable Cisco router, you can enable a global IPv6 prefix on a subnet in an afternoon and start servicing IPv6 customers just like Facebook did. Or, if you don’t yet want to be part of the IPv6 Internet, you can also use LISP to interconnect internal islands of IPv6 networks over your existing IPv4 network to start building out your IPv6 (and LISP) experience.
If you already run IPv6, you can experience Facebook’s LISP network first-hand by visiting http://www.lisp6.facebook.com, whether you run LISP or not. You can learn more about LISP at the official page http://www.cisco.com/go/lisp or the engineer-maintained http://lisp.cisco.com/ (which itself runs over LISP)!
How to start using LISP?
These two scenarios described above (IPv6 islands and IPv6 Web Presence) are shown in more detail in the Cisco Locator/ID Separation Protocol IPv6 Transition Strategy brochure, and the detailed sample configurations associated with those scenarios can be found in this white paper. These two links form your reading assignment, and the white paper provides the “lab guide.” As always, we welcome your questions and discussion at the World IPv6 Day – IPv6 Transition support forum!