Session Border Controllers: Rationalizing the Border of the Network
As today’s communications networking environment rapidly changes and becomes increasingly complex and highly nuanced, an increased emphasis on IP has become the new method for delivering voice and video services. Meanwhile, converged applications are also growing quickly and IP video traffic is exploding – this makes sense given the growing array of combined services that are in demand by consumers. More and more IP networks are being installed and used as core networks. Until recently, these were considered “adjunct” networks connected to “core” time division multiplexing (TDM) networks through gateways.
Core IP networks used as primary service delivery networks translates into multiple networks – both internal and external to service providers – being available for providing end-to-end services to customers. Since global communications will still include a large TDM component into the foreseeable future, “all-IP” networks will still need to interconnect with existing TDM networks. This means that there will be service delivery challenges encountered in making these disparate networks work well together. This will place a premium on technology solution providers.
As such, service providers are looking for solutions that provide a broad set of capabilities that enable both IP and TDM networks. A new set of requirements relating to end-to-end service integrity, network security, and application support has emerged due to the blended nature of services being offered today that may involve multiple participants in the service delivery supply chain in order to connect customers and content.
As service providers transform their core networks to IP, Session Border Controllers (SBCs) are taking on a new role. SBCs not only provide functionality at the borders between networks to support baseline voice services, but they also enable and support a host of new IP-based services and applications, including high-definition (HD) voice and real-time video communications.
SBCs: What and Why
Traditionally, service providers used SBCs as an “interconnect” device located at the “peering” border, or Network-to-Network Interface (NNI), between interconnecting different service providers and as a border element between the service provider core network and their access network connecting to enterprises and residential customers.. But as more and more IP “sessions” are going through SBCs, this promotes larger capacity and higher-performance devices, and separate load-balancing systems. The contemporary SBC, or at least its media control element – the Border Gateway Function (BGF) – can be seen as an IP “gateway” connecting IP networks with each other. It performs functions similar to traditional media gateways that bridge IP and TDM-based networks.