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Like many network infrastructure devices, session border controllers, or SBCs, were engineered for dedicated hardware. Similar to how Layer 4-7 switches initially required custom application-specific integrated circuits to process packets, SBCs relied on purpose-built hardware to perform their functions in managing how calls are handled over a voice over IP network.
That all changed as Intel chips became more powerful. SBCs, as with switches and other components, no longer needed custom hardware. Instead, they could run on commodity hardware. And, once a network function can be accomplished on a standard Intel platform, it's a candidate for virtualization.
Let's take a look at the benefits of the virtual session border controller.
The quickest way to understand those benefits is to acknowledge the advantages of virtualization in general: hardware savings, better resource utilization and deployment flexibility. You get all that and more with virtual SBCs. Here are a few in particular.
Better investment protection versus hardware. One of the challenges of implementing any hardware-based network infrastructure component is selecting the correct size for your network. A lower-end SBC would be less expensive but could become a bottleneck as demands grow. A higher-end SBC might cost too much and leave you with excess capacity.
With virtual SBCs, those resource issues disappear. The host system running your virtual SBC can also be used to run other VMs, providing you with additional flexibility.
Scalability. This leads us right into scalability. When functions were tied to hardware, adding capacity required a forklift upgrade as lower-end hardware was replaced with more power components. This is not an issue with virtual SBCs.
Instead, companies need only assign more hypervisor resources. Oracle's small virtual SBC, for example, can scale up to four virtual CPUs and 16 GB of capacity to handle higher session counts. Keep in mind that some vendors might cap their virtual SBCs at a certain level, requiring customers to upgrade their licenses if their session count demands escalate.
Availability. High availability (HA) is always good, but at what price? With hardware, HA meant purchasing a redundant system engineered to take over if the primary SBC failed. With virtual session border controller designs, HA means allocating a standby VM that can run the virtual SBC if circumstances warrant. That's a more affordable option than costly redundant hardware.
These are just a few of the advantages virtualization can offer to companies considering a migration to virtual SBCs. One caveat: SBC features, such as transcoding, require digital signal processers that are not a resource typically virtualized by hypervisors. Make sure you inform your SBC vendor about your exact requirements.
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