Network 2.0: Virtualization without Limits
So the theme of the day is Network Virtualization, Software defined networks and taking virtualization to its logical conclusion i.e. server, storage and network in a giant resource pool that can be allocated/assigned any which way. Although its easier said then done. Server and Storage virtualization were a bit simpler since we were dealing with one OS that needed to provide the right abstraction layer. The H/W resource pool (disk, cpu, network, memory, etc) was managed by the single OS so provisioning it between various virtual machines or storage pool was a bit simpler. The network by definition is useful only when multiple devices are connected and trying to treat them as a single resource pool is harder. A virtual networks has to deal with not just links, bandwidth, latency and queues but also
higher level functionality like routing, load balancing, firewalling, DNS, DHCP, VPN, etc. etc. And we haven’t even talked about how this all will hook up together along with virtual machines and virtual storage pool in a easy manner. Now before you argue that every component is already virtualized (which is very true), one could argue that it still doesn’t give me a virtual network. It is same as someone wanting a dinner and is instead served raw potatoes, onions, tomatoes, eggs, etc and shown the stove to make his own Omelette.
So having pioneered virtual switching and resource control in the server OS (Solaris to be specific – the project was called Crossbow that I started in 2003 and got integrated in OpenSolaris in 2008), I set out to do the same for larger networks in the form of Pluribus Networks Inc and apply the hard lessons we learned from enterprise customers. This is what we call Network 2.0: Virtualization without Limits. The real reason it is a tough problem to solve is due to switching needing to be very high performance and low latency. It forces all the switching functionality to be inside a very highly complicated ASIC which does all the hard work in shuffling 1.2 Terabits per seconds of data and sub micro second latencies and as such doesn’t need much software on top. The embedded OS controlling the switch is mostly used for just configuring the switch chip using a cli (command line interface) that allows the administrator to control and configure each component on the switch but almost nothing else. So when we started playing with some of the prototype next generation boxes that our friends at Fulcrum and Broadcom gave us, we just kept asking if I could have a real OS running the chip to be able to do something more useful. So we asked our friends again if there was someway to put a full fledged OS on top (being the OS person I have been for most of my life). And that was when I realized that to solve the network virtualization problem, we really need a OS that understand resource pools and virtualization on the chip. But a single switch by itself is not very interesting so we need a OS that controls all the switches. Hmm – one OS that controls them all (borrowing from LOTR which reminds me to ask Peter Jackson whatever happened to the prequel)!! So before we can even start building anything more complicated, we built a network hypervisor that has semantics similar to a tight coupled cluster but controls a collection of switches and scales from one instance to hundred plus instances.
The Network OS is finally taking life and is able to treat the network exactly as a one giant resource pool. Please don’t confuse the Network OS with typical management layer that manages a collection of devices. We do still need a management layer to configure and manage the OS but the policy enforcement, congestion control and resource management across all devices is done by the OS. It is same as a server cluster doesn’t get rid of the management layer but actually gives the management layer something that is more manageable.
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