Insieme’s Insides Use (Gasp!) an Overlay Protocol

Insieme's Insides Use (Gasp!) an Overlay Protocol

VMware employees should get a good chuckle out of Cisco‘s Insieme launch on Wednesday, because for all its trash talking about overlays, Insieme is using the VXLAN protocol to run its data-center fabric.

The network overlay model is being championed by a majority of the other vendors doing software-defined networking (SDN), especially VMware, which many believe is the rival that should worry Cisco the most. (Big Switch Networks on Insieme’s side in its dislike of overlays, but it’s hard to see Insieme going on stage and saying, “We’re just like Big Switch.”)

Since its public introduction in June, Insieme has said network overlays suck. The claim is that overlays ultimately won’t scale enough and that they reduce visibility, making network monitoring, troubleshooting, and policy enforcement more difficult.

But VXLAN isn’t so bad after all, apparently.

In launching Insieme’s products and architecture Wednesday, Cisco revealed that the Application-Centric Infrastructure (ACI) uses VXLAN in the fabric that connects leaf switches to spine switches. Blasphemy?

What Insieme Has in Common With QFabric

It’s a little bit like the debate that surfaced around Juniper‘s QFabric data-center fabric. Upon launching QFabric in 2011, Juniper stressed its support for open standards. But QFabric turned out to be running a proprietary protocol across its interior; that’s how it builds the connection between one switch and another.

That doesn’t cancel QFabric’s claims of openness, Juniper says, because nobody else besides Juniper is supposed to talk with that proprietary protocol. Other vendors would use open standards to connect to QFabric; they don’t get exposed to QFabric’s interior. In that sense, QFabric is still an “open” environment.

Similarly, Cisco is using VXLAN as an interior fabric protocol. In that sense, it’s hidden from the outside world.

Now, there’s a major semantic difference here. Juniper can still claim to be “open” because other companies can participate in QFabric in an open fashion. But in Insieme’s case, the network really is doing an overlay. You can’t get around that, because it’s what VXLAN does. It’s just a more contained overlay than what VMware and others do, confined to connecting top-of-rack switches to the data-center spine.

Insieme and Cisco probably won’t change their tune on overlays. It’s too good a debating point against VMware.

But yes, Insieme uses an overlay protocol to build its data-center fabric. And you know, that’s not all that shocking; Cisco helped create VXLAN, after all. For what it’s worth, Insieme is also setting up the Nexus lines to participate in overlays if they really have to — its upgrades to the NX-OS operating system include full, unashamed support of overlay networks through VXLAN bridging and routing. (Most vendors do just the bridging part, Insieme says.)

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  1. Nigel StephensonNigel Stephenson says

    I’ll let my former Juniper colleagues respond to the ‘is QFabric just a header?’ question – but the answer is no IMHO 😉

    Overlays are great when looking from the top down. They make a great logical map on the management screen and for applications’ use. Personally I think they are the future.

    However, the very thing that makes them powerful COULD be their downfall in a practical deployment: the abstraction from the physical network.

    This extraction is great (and needed) for agility and flexibility, but to deploy any form of tunneling without some level of understanding of the physical infrastructure could be inefficient at best and dangerous at worst. So the key question becomes: ‘how do I deploy overlay technologies while still accounting for physical infrastructure characteristic?’. One answer is to make the physical infrastructure act (physically not logically) as a single switch. That in essence is QFabric.

    Stitching spine and leaf together with an overlay may simplify the management, but at the physical layer you still have multiple switches and associated latency and jitter to contend with.

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