LISP started as yet-another ocean-boiling project focused initially on solving the “we use locators as identifiers” mess (not quite), and providing scalable IPv6 connectivity over IPv4-only transport networks by adding another layer of indirection and thus yet again proving RFC 1925 rule 6a. At least those are the diagrams I remember from the early “look at this wonderful tool” presentations explaining for example how Facebook is using LISP to deploy IPv6 (more details in this presentation).
Somehow that use case failed to gain traction and so the pivots1 started explaining how one can use LISP to solve IP mobility or IP multihoming or live VM migration, or to implement IP version of conversational learning in Cisco SD-Access. After a few years of those pivots, I started dismissing LISP with a short “cache-based forwarding never worked well” counterargument.
Minh Ha left this comment on the Packet Forwarding 101 blog post. As is usually the case, it’s fun reading and it would be a shame not to repost it as a standalone blog post (even though I don’t necessarily agree with all his conclusions).
I always enjoy Bela’s great insights, esp. on hardware and transport networks, but this time I beg to differ. LISP, is a false economy. It was twisted from the start, unscalable right from the get-go. In Networking and OS, to name (ID) something is to locate it, and vice versa. So the name LISP itself reflects a false distinction. Due to this misconception, LISP proponents are unable to establish the right boundary conditions, leading to the size of xTRs' RIB diverging (going unbounded). In a word, it has come full circle back to BGP, an exemplary manifestation of RFC 1925 rule 6.
I got several questions along the lines of “why is Cisco pushing LISP instead of using EVPN in VXLAN-based Enterprise campus solutions?”
Honestly, I’m wondering that myself (and maybe I’ll get the answer in a few days @ NFD16). However, let’s start at the very beginning…
Last week Stephen Foskett and Greg Ferro brought back their merry crew of geeks (and a network security princess) for the third Networking Tech Field Day. We’ve met some exciting new vendors (Infineta and Spirent) and a few long-time friends (Arista, Cisco, NEC and Solarwinds).
Infineta gave us a fantastic deep-dive into deduplication math, and Spirent blew our socks off with their testing gear. As for the generic state of the networking industry, the “I’m excited” rating from last autumn changed to this (HT @reillyusa):
Immediately after VXLAN was announced @ VMworld, the twittersphere erupted in speculations and questions, many of them focusing on how VXLAN relates to OTV and LISP, and why we might need a new encapsulation method.
VXLAN, OTV and LISP are point solutions targeting different markets. VXLAN is an IaaS infrastructure solution, OTV is an enterprise L2 DCI solution and LISP is ... whatever you want it to be.
In early autumn of 2010, a “DRAFT on Cisco Nexus 1000V LISP Configuration Guide” appeared on CCO. It’s gone now (and unfortunately I haven’t saved a copy), but the possibilities made me really excited – with LISP in Nexus 1000V, we could do close-to-perfect vMotion over any IP infrastructure (including inter-DC vMotion that requires stretched VLANs and L2 DCI today). Here’s what I had to say on this topic during my Data Center Interconnect webinar (buy a recording).
I’ve been mentioning LISP several times during the last months. It seems to be the only viable solution to the global IP routing table explosion. All other proposals require modifying layers above IP and while that’s where the problem should have been solved, expecting those layers to change any time soon is like waiting for Godot.
If you’re interested in LISP, start with the introduction to LISP I wrote for Search Telecom, continue with the LISP tutorial from NANOG 45 and (for the grand finale) listen to three Google Talks from Dino (almost four hours).