Even though virtualization of servers, switches and other infrastructure components is commonplace these days,...
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virtualized routers -- using virtual routing software -- remain sparse by comparison. It's not that routers can't be virtualized. In fact, there are many virtual router options available today. The main issue with deploying virtual routers, as opposed to physical router appliances, has less to do with availability and more to do with the duties a router is required to perform.
In this article, we're going to look at the benefits and drawbacks when virtualizing router services in enterprise networks. And, ultimately, we'll help you determine which environments are right for virtualization and when you might be better off deploying traditional, physical appliances.
Virtual routing software benefits
Flexibility and scalability are the two immediate benefits when moving to a virtual router platform. If your physical hardware can support it, you can add any number of virtualized router interfaces to tackle large infrastructure deployments.
Virtual routers are also useful in situations where you operate in multi-tenant environments. Instead of purchasing separate, physical router appliances for every tenant, you simply spin up a virtual routing software instance for each company or department. Then, simply let those individual IT departments manage the configuration and firmware maintenance.
Lastly, virtual routers may be your only option. This is almost always the case for popular public cloud service providers, such as Amazon Web Services, Microsoft Azure and Google Cloud.
Virtual routers can also be a cheaper long-term option for businesses of all types. If you've already spent money on a blade-server chassis for your data center, you can forgo the capital expenditure of purchasing a physical appliance and instead opt for a lower-cost -- or sometimes free -- virtualized router option. Virtualization also equates to a smaller data center footprint. By consolidating more functionality into a blade server, it means you have less physical rack space and devices to power. For large organizations, this is a cost savings that cannot be ignored.
Drawbacks of virtual routing software
One of the first stumbling blocks you will likely come across when considering a virtual router is the physical connectivity types that may be required. While the Ethernet protocol is the de facto standard on LANs and within many enterprise data centers, you should consider that routers often must integrate with traditional telecommunications technologies, including T1s, T3s and asynchronous transfer mode. Once you leave the relative comfort zone found with Ethernet connectivity, virtual router limitations are exposed.
The other major drawbacks for virtual routers tend to revolve around the topic of data security. Many network administrators prefer deploying purpose-built hardware and software appliances. This is especially true when you are dealing with network perimeters, such as the internet or the WAN. While this concern is somewhat debatable, it's still on the minds of many IT decision-makers.
A more valid security concern is exposed when you opt to deploy virtual routers in a multi-tenancy environment. Because you are sharing the same physical hardware, it raises the possibility that another tenant could potentially affect your network performance, or possibly even bring it to a halt. An example of this would be a denial-of-service attack on one router that can affect other virtualized components on that blade server.
Depending on your deployment type and dependency on shared physical resources, this may be more or less of a concern. But any time you share hardware with multiple virtualized devices, it is something to think about.
The final thing to think about when considering virtual routing software is the fact you may not have control over the physical server on which it's operating. If that's the case, you need to trust another group within your IT department -- or a third-party service provider. You must have the utmost confidence with whoever is managing your virtual router, as it's undoubtedly a critical component of your overall network architecture.
As you can see, there are definite benefits and drawbacks when it comes to deciding on whether to deploy a virtual or physical router appliance. Fortunately, there are some obvious deployment scenarios where one choice stands out from the rest. For example, virtual routers are ideal in situations where you don't manage the underlying physical infrastructure in the first place. The most common example of this would be an infrastructure-as-a-service cloud deployment. Here, a virtual router is the most obvious choice. And as we mentioned earlier, it's also often the only choice.
Virtual routers are also most at home within data centers. Here, the flexibility and scalability options shine. You also can take advantage of multi-tenancy capabilities if that's a requirement for your data center.
Physical router appliances, on the other hand, are still the preferred option at the network edge. The far greater variety of interface options when compared to virtual routers are one clear reason why physical routers are still being deployed at internet and WAN boundaries. Another benefit rests in the confidence that purpose-built appliances hold in regard to hardening the security of critical network intersections where you connect your LAN to the outside world.
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