Issue link: https://cp.revolio.com/i/141720
small and using routing across subnets remains the right thing to do. When is the last time you've designed a large flat L2 network and have survived to tell the story? If L3 overlays can enable agile cross-subnet connectivity across PODs, flexibility can be obtained without sacrificing traditional best practices, and subnets can be kept small and manageable. To be practical, we should always justify technology with use cases. I might be too cynical, but I believe that extra flexibility always comes at a cost; does the cost of extra flexibility come with significant enough benefits/ROI? Only use cases can keep us grounded in reality. Sometimes the cost is fully justified, other times it's not. I completely buy "migration" as a legitimate use case for L2 overlays, but it troubles me that L2 overlays are presented as an "allor-nothing" alternative to VLANs. They should be able to co-exist with VLANs and be inserted more gently when and where they're actually needed. Instead, if I want to preserve the ability to do a migration, I need to use VXLAN, NVGRE or STT all the time. To me it's like forcing me to live in an RV the whole year just because one day I might want to take a road trip. In a way, I wish VXLAN was a bit more like OTV: OTV coexists with VLANs, and doesn't displace them. I have to admit I'm still struggling to see the real applicability of L2 overlays in many of the use cases where they're touted to be better than the old. It might just be a technology maturity problem, but in the back of my mind I'm afraid the industry just might have overreacted, responding to a management plane problem with a {management plane + data plane} solution. We keep hearing about VLANs being the problem that needs fixing, and frankly sometimes it feels a bit like an irrational witch-hunt. If VLANs were the problem, then certainly VXLAN might be the solution. But here's a revolutionary thought: what if instead the problem is Ethernet? If Ethernet is the problem, a good emulation of Ethernet is going to suffer from exactly the same limitations of the original Ethernet. Do VLANs have a control plane and a data plane? No, Ethernet does. All VLANs have is an (almost non-existent) management plane. The only significant faults of VLANs are that they're hard to create/delete/prune and that they're limited to a maximum of 4,000 partitions of a physical Ethernet network. The bigger scalability issues are all due to Ethernet, the completely random 6 bytes addresses and the broadcast-based discovery services that have been built on top of it. Anything that emulates Ethernet scales as much as Ethernet does. And if that's true, IP and routing is what saves us and makes us scale. It helped us scale in the old world, and it still will in this shiny new virtual world. Don't throw away your old networking books just yet. I bet on IP. n About the Author: Marco Di Benedetto is Co-Founder and CTO of Embrane. SprngDCJ_8375w525_3fx.q8_DCJ Half page ad 3/28/13 9:34 AM Page 1 END-TO-END RELIABILITY: MISSION CRITICAL FACILITIES DRIVING PERFORMANCE 2013 SPRING CONFERENCE Register online today at www.7x24exchange.org CONFERENCE KEYNOTE Going for the Gold 2013 Spring Conference Corporate Leadership Program Partners (at press time) Mike Eruzione MARQUIS PARTNER Captain of the 1980 U.S. Olympic Hockey Team and Subject of the Hit Film, Miracle GOLD PARTNERS How to Stop Hackers Affecting Your Performance SILVER PARTNERS Kevin Kealy Senior Vice President of Enterprise Networking Fidelity National Information Services ViaWest – Performance Challenge: Tier IV, PUE 1.2 Modular Build Out Dave Leonard BRONZE PARTNERS Senior Vice President, ViaWest Gary Orazio, P.E. TM PRINCE WILLIAM C O U N T Y, V I R G I N I A TM President, Swanson Rink Robert Yester, P.E. ATD www.datacenterjournal.com Executive Vice President, Swanson Rink MEDIA PARTNERS THE DATA CENTER JOURNAL | 29 Questions? call 646.486.3818 www.7x24exchange.org June 2 - 5, 2013 | Boca Raton Resort & Club | Boca Raton, FL