Locator/ID Separation Protocol (LISP)

LISP is a networking technology that has been searching for a relevant problem for a decade and a half (the LISP IETF working group started in the spring of 2009). Initially, I was cautiously optimistic. However, as LISP pivoted from an IPv6-over-IPv4 solution to a multihoming solution, then VM mobility and IP endpoint mobility solution, until it finally landed in Cisco Campus BU as the foundational technology of Software-Defined Access, I lost all hope.

LISP started as a DNS-like cache-based packet forwarding technology. Eventually, reality intervened, and the LISP believers rediscovered the flaws of cache-based forwarding. It looks like LISP pivoted to become a topology-driven PUB-SUB protocol. Assuming that’s correct, there’s little conceptual difference between LISP and EVPN. It’s just a question of defining a suitable set of policy mechanisms and developing an optimal implementation.

Discussing the benefits and drawbacks of LISP or EVPN thus makes as much sense as debating the number of angels dancing on the head of a pin, but that has never stopped people from doing one or the other.

Just in case you want to know more, you will find some details in the LISP-related blog posts I wrote since 2010:

• Introduction to LISP (2010)
• VXLAN, OTV and LISP (2011)
• We Just Might Need NAT66/NPT66 (and Not LISP) (2011)
• Networking Tech Field Day #3: First Impressions (2012)
• Mobile ARP in Enterprise Networks (2012)
• Hot and Cold VM Mobility (2013)
• VXLAN and OTV: The Saga Continues (2014)
• Why Is Cisco Pushing LISP in Enterprise Campus? (2017)
• When All You Have Are Stretched VLANs... (2020)
• Grasp the Fundamentals before Spreading Opinions (2020)
• Packet Forwarding 101: Header Lookups (2022)
• Cache-Based Packet Forwarding (2022)
• Repost: LISP Is a False Economy (2022)
• Should We Use LISP? (2022)
• So-Called Modern VPNs: Marketing and Reality (2022)
• Multihoming Cannot Be Solved within a Network (2022)
• LISP vs EVPN: Mobility in Campus Networks (2024)