"Session Border Control in Access and Interconnect Networks" white paper


Session Border Controllers (SBCs) are playing an increasingly critical role in two key areas of emerging next generation carrier networks. Access SBCs and Interconnect SBCs both manage and secure signaling and media functions in next generation architectures, such as those defined by the 3GPP LTE Advanced standards, but they have distinctly different responsibilities. The Perimeta portfolio of Session Border Controllers, from Metaswitch, is uniquely designed to meet these diverse requirements.

Perimeta in the Access layer

With the continuous registration requests originating from SIP User Agent endpoints, SBCs deployed in access infrastructures experience higher traffic loads than devices deployed at other points in a network. As these endpoints evolve from plain old telephony to delivering a unified communications experience, the number of distinct SIP messages Access SBCs must handle will increase exponentially. This will include not only multiple registrations but also instant messaging, SMS and presence traffic that could break the classic scaling models of integrated SBC platforms.

The traffic loads on Access SBCs are also unpredictable. Local or regional events, promoting telephony service usage, or even intermittent network instability can result in peaks and valleys in signaling messages. Access SBCs must also support trusted and untrusted endpoints, so they are also more susceptible to attacks from nefarious sources or simply unsupported user agents that might unwittingly flood signaling functions with non-conforming messages. Access SBCs must therefore use complex traffic profiles, policies, rules and traffic normalization techniques.

Operating as an Access SBC, Perimeta features a unique access control list implementation, granular rules and SIP normalization though our exclusive message manipulation framework (MMF), coupled with an architecture designed for independent scaling of signaling verses media data. Representing a new class of Access SBC, Perimeta can meet stringent demands without compromising on throughput or capacity. 

Perimeta at Interconnect peering points

With more predictable pre-registered traffic patterns, from trusted internetworking peers that have already normalized SIP messages, Interconnect SBCs have far more predictable call flows and message profiles than Access SBCs. However, with multiple peering partners it is more important to route traffic depending on dynamic metrics, such as link cost and loading.

As an Interconnect SBC, Perimeta features superior message and packet processing combined with unmatched, independent scaling of signaling and media to handle the high loads of peering traffic efficiently and cost effectively. Extending exceptional tuning capabilities, Perimeta provides powerful Least Cost Routing, load balancing, and structured routing rules and algorithms, enabling the most efficient use of critical trunk interfaces.