Just how robust is software SBC infrastructure really? - QKON SA

The integration of software Session Border Controller (SBC) infrastructure is associated with advantages like a reduction in Opex and Capex, flexibility, improved ROI, as well as a prolonged infrastructure life cycle. However, while momentum in this area of the market is on the increase, there is still a debate amongst telecommunication specialists as to whether software SBCs can truly replace the functionality of their hardware counterparts.

A software SBC is a SBC application running on an off-the-shelf server, or on a virtual machine. A hardware SBC is proprietary hardware purposely built for SBC applications. 

An evaluation of the suitability of the infrastructure is based on aspects such as cost, capabilities, installation location, and the specific application. It is a topic of growing interest and one that leading UC product distributor Q-KON South Africa continues to follow very closely. 

Q-KON SA has been a leading value added distributor since 2005, focussing exclusively on the VoIP, SIP trunking, and Unified Communication markets.  

The company’s distribution portfolio includes gateways, MSBRs, edge SBCs, core SBCs, SBAs, UC Phones, VoIP recording platforms and billing solutions from industry leaders such as AudioCodes, Sonus, RedBox, BroadSoft and PhonEX One. 

Many of these industry specialist manufacturers have conducted research in order to make the market more aware of the different considerations and the impact these have on infrastructure procurement, integration and application.  

In its whitepaper on the subject, software and hardware SBC manufacturer AudioCodes provides a useful and practical summary of the strengths of each option and specific considerations for the network engineer during network planning.  

Software SBCs with their large caches and high spec Intel CPUs are quite capable of taking care of the SIP Encryption, NAT traversal, and DoS protection required on the signalling layer. On the data layer, the software SBC processes the RTP packets with ease.  

It is on the media layer, where voice transcoding, T.38 fax transcoding, and DTMF detection is done, where it gets more difficult. Hardware SBCs use Digital Signal Processor (DSP) chips to handle media layer activities. DSPs are highly optimized for this application. Software SBCs using a general purpose CPU, support a wide set of instructions unrelated to the handling of media, and as such, are less efficient compared to DSPs. Intel cores are also unbalanced when comparing their signalling and media throughput with their transcoding throughput. 

So which SBC applications are suitable for software SBC’s and which are not? Regardless of the SBC application, whether it is in the enterprise or on the service provider’s edge, or part of the service provider’s network, the answer lies in the number of transcoded sessions required. If a large number is required, say more than two hundred or three hundred sessions, the answer is hardware SBC. 

“We agree with the point raised by AudioCodes that the advent of new technologies, such as WebRTC, introduces additional vocoders. This means that, at least for the foreseeable future, large scale transcoding will be needed - and, as such, hardware SBCs and software SBCs, will need to co-exist for some time to come” says Tjaart de Wet, Managing Director of Q-KON SA.