Fabric switching systems have been a popular solution for many companies in the past few years. Juniper has QFabric and Brocade has VCS. For those not invested in fabrics, the trend has been to collapse the traditional three tier network model down into a spine-leaf architecture to optimize east-west traffic flows. One must wonder how much more optimized that solution can be. As it turns out, there is a bit more that can be coaxed out of it.
Shine A Light On Me
During Interop, I had a chance to speak with the folks over at Fiber Mountain (@FiberMountain) about what they’ve been up to in their solution space. I had heard about their revolutionary SDN offering for fiber. At first, I was a bit doubtful. SDN gets thrown around a lot on new technology as a way to sell it to people that buy buzzwords. I wondered how a fiber networking solution could even take advantage of software.
My chat with M. H. Raza started out with a prop. He showed me one of the new Multifiber Push On (MPO) connectors that represent the new wave of high-density fiber. Each cable, which is roughly the size and shape of a SATA cable, contains 12 or 24 fiber connections. These are very small and pre-configured in a standardized connector. This connector can plug into a server network card and provide several light paths to a server. This connector and the fibers it terminates are the building block for Fiber Mountain’s solution.
With so many fibers running a server, Fiber Mountain can use their software intelligence to start doing interesting things. They can begin to build dedicated traffic lanes for applications and other traffic by isolating that traffic onto fibers already terminated on a server. The connectivity already exists on the server. Fiber Mountain just takes advantage of it. It feels very simliar to the way we add in additional gigabit network ports when we need to expand things like vKernel ports or dedicated traffic lanes for other data.
Quilting Circle
Where this solution starts looking more like a fabric is what happens when you put Fiber Mountain Optical Exchange devices in the middle. These switching devices act like aggregation ports in the “spine” of the network. They can aggregate fibers from top-of-rack switches or from individual servers. These exchanges tag each incoming fiber and add them to the Alpine Orchestration System (AOS), which keeps track of the connections just like the interconnections in a fabric.
Once AOS knows about all the connections in the system, you can use it to start building pathways between east-west traffic flows. You can ensure that traffic between a web server and backend database has dedicated connectivity. You can add additional resources between systems that are currently engaged in heavy processing. You can also dedicated traffic lanes for backup jobs. You can do quite a bit from the AOS console.
Now you have a layer 1 switching fabric without any additional pieces in the middle. The exchanges function almost like a passthrough device. The brains of the system exist in AOS. Remember when Ivan Pepelnjak (@IOSHints) spent all his time pulling QFabric apart to find out what made it tick? The Fiber Mountain solution doesn’t use BGP or MPLS or any other magic protocol sauce. It runs at layer 1. The light paths are programmed by AOS and the packets are swtiched across the dense fiber connections. It’s almost elegant in the simplicity.
Future Illumination
The Fiber Mountain solution has some great promise. Today, most of the operations of the system require manual intervention. You must build out the light paths between servers based on educated guesses. You must manually add additional light paths when extra bandwidth is needed.
Where they can really improve their offering in the future is to add intelligence to AOS to automatically make those decisions based on thresholds and inputs that are predefined. If the system can detect bigger “elephant” traffic flows and automatically provision more bandwidth or isolate these high volume packet generators it will go a long way toward making things much easier on network admins. It would also be great to provide a way to interface that “top talker” data into other systems to alert network admins when traffic flows get high and need additional resources.
Tom’s Take
I like the Fiber Mountain solution. They’ve built a layer 1 fabric that performs similarly to the ones from Juniper and Brocade. They are taking full advantage of the resources provided by the MPO fiber connectors. By adding a new network card to a server, you can test this system without impacting other traffic flows. Fiber Mountain even told me that they are looking at trial installations for customers to bring their technology in at lower costs as a project to show the value to decision makers.
Fiber Moutain has a great start on building a low latency fiber fabric with intelligence. I’ll be keeping a close eye on where the technolgy goes in the future to see how it integrates into the entire network and brings SDN features we all need in our networks.
That sounds very similar to what Plexxi were doing a year or so ago
Keys to making this kind of hybrid circuit/packet design work in real life are a physical layer (cabling, connectors, the PHY chip that drives the cable) cheap enough that you can use a lot more of them than traditional designs do; a place where having a lot of uplinks is affordable (perhaps the ToR switch rather than the NIC, on all but the largest servers); a default place to send traffic which isn’t the elephant flows, big storage users, or other high traffic (ie to the traditional switched spine); the instrumentation and analysis to figure out where the heavy traffic is; and some SDN software which keeps track of available circuit endpoints, programs circuit switch paths between them, garbage collects circuit paths which are no longer in heavy use; and somehow manages to inform the endpoints of the comings and goings of circuit connections.