When you think of your ideal campus network, the term “web-scale” may not immediately come to mind. After all, the term web-scale is something you’re more likely to associate with the cloud than with your network. But you might be surprised to learn that your ideal campus network fits the definition of a web-scale network to a T.
Fundamentally, a web-scale network functions as a single unit that can grow and change on demand, without requiring hands-on reconfiguration of multiple switches or mass hardware replacement. And because it functions as a single unit, a web-scale network can also give you full visibility into the health of your network, end-to-end.
The primary way web-scale networks achieve this flexibility and visibility is by decoupling or disaggregating the hardware and the network operating system (NOS) that runs on the hardware. Since the advent of specialized hardware networking devices, the operating system and hardware have been tightly coupled together. Proprietary NOSes often have platform-independent code that runs only on specialized hardware. Because of that, upgrading to a new software version often means buying new hardware. In some cases, that may be as simple as buying additional RAM to support the new version. In more extreme cases, it means buying a new switch because your existing hardware simply isn’t compatible. Regardless, upgrading hardware requires substantial downtime.
This has led to many organizations opting to stay on old, inflexible and insecure software versions. Eventually, when the need for increased capacity necessitates new hardware, it often happens that the new NOS that ships with the new hardware can’t accept the old configuration as-is. Configurations have to be reworked and retested to ensure they perform as expected. Late nights and bad experiences reinforce the notion that it’s better to just leave the network alone. “If it ain’t broke, don’t fix it,” is often the prevailing attitude. Unfortunately, the old paradigm is broken, but nobody knew how to fix it.
Nobody until now.
Fast-forward to today. With web-scale networking, you’re no longer locked into one vendor’s hardware. Many different manufacturers are producing white-box switches capable of running a variety of network operating systems. The hardware comes in all shapes and sizes, ranging from small switches you stick into a dusty closet, to enormous modular switches that require three Olympic deadlifters to install.
And the flexibility extends beyond just the switch hardware. You can also choose the optical and electrical pluggables you want to use. For example, if you require specific optics to support your existing fiber runs, you have a variety of vendors to choose from — you don’t have to purchase from the same vendor that makes your switch. You can buy the hardware that suits your needs without having to worry whether it’s compatible with your switch or NOS.
Having the freedom to mix and match hardware makes it easier to stay within budget. You can purchase switches from different manufacturers, knowing that they’ll all work together. If vendor A is cheaper, you can buy from them. Tomorrow, when you need to add more buildings, or even just replace a switch, and you find that vendor B is cheaper, you can go with them.
Agility through automation
Although disaggregating the hardware and software is important for flexibility, scalability and cost, the ability to grow and change your network on demand happens using automation. With automation, all of your configurations are stored in one place. If you need to make a change to multiple switches, you don’t have to log into a dozen switches and start typing. Using automation, you make your changes in one centralized repository and push them out to your switches with the flip of a switch.
This makes network upgrades much easier. Not only can you rip and replace hardware, knowing that it will be compatible, but you can also easily push the existing configuration to the new switch, and it will just work.
But the benefits of automation don’t just apply to switch replacements. You can quickly and safely make sweeping changes that would otherwise require careful switch-by-switch configuration. For example, you can define a set of baseline security controls that you automatically push out to all switches. If a worm gets loose in your network and starts replicating, you can respond quickly with the push of a button by blocking the appropriate ports or addresses throughout the network.
Of course, network automation isn’t new. All of the big switch vendors have their own automation tools. But if you want to use automation with a proprietary NOS, you’ll likely have to use the vendor’s product, which you may not like. However, a Linux-based NOS (such as Cumulus Linux) swings the door wide open for you to use whatever automation tools you like. Ansible, Chef and Puppet are popular automation tools that run on Linux, which means they can run on the Linux-based NOS of your choice. Once again, this gives you the flexibility to choose the automation tool that works for you.
Web-scale networks are all about choice
Ultimately, your campus web-scale network should be one that can adapt to ever-changing network needs. It gives you the freedom to choose your switch hardware, software and tooling. Web-scale networks also adapt to your budget. If you decide that a particular hardware vendor isn’t right for you, you can migrate to a new vendor in a modular fashion, replacing one switch at a time as needed. You don’t have to rip-and-replace a collection of switches at a time just to maintain compatibility.
Best of all, you don’t have to wait to get started with web-scale networking. You can start small with just one or two switches and experiment with different NOS’s. You can see how well those switches play with your existing gear, try out different automation tools and get comfortable with the idea of disaggregation. Once you get your hands on a white-box switch running an open NOS, you’ll probably find yourself thinking, “Why didn’t I do this sooner?”
Need more resources and information to help you get started? Head over to the web-scale networking 101 page for a crash course in all things web-scale!