VoIP Infrastructure in Service Provider Networks with BIG-IP Devices

Scaling VoIP

VoIP can be considered either a lucrative opportunity or a competitive threat, depending on a service provider’s current business model. Either way, VoIP is inevitable for all service providers—even for those traditional mobile and wireline providers that continue to prefer traditional voice technologies.

According to a study by Frost & Sullivan, mobile VoIP alone (excluding fixed VoIP) will constitute a $30 billion business worldwide by 2015—up from just $600 million in 2008. For this reason, Frost & Sullivan is encouraging all mobile providers to begin embracing VoIP, as is research firm Ovum, based on its separate evaluation of the mobile market.*

F5 has been helping service providers successfully implement and scale their VoIP offerings for nearly a decade. Support for VoIP, IMS, and SIP is integral to F5’s solutions for service providers, and was designed specifically to satisfy the needs of even the world’s largest network operators.

The key to enabling a truly scalable integrated messaging network is by offering intelligence and flexibility throughout the Service Delivery Network (SDN), an architecture designed to manage service delivery to users and devices. The F5 BIG-IP platform acts as the strategic point of control for F5’s entire Service Delivery Network—including the service provider-class, NEBS-compliant F5 VIPRION. VIPRION provides scalability and mission-critical high availability with both local and global load balancing. A single VIPRION chassis holds up to four hotswappable blades, and is capable of supporting up to 64 million concurrent sessions—and millions more subscribers.

BIG-IP solutions also support separate Message-Based Load Balancing (MBLB), purpose-built for messaging protocols used for subscriber management and signaling. MBLB provides full support for load-balancing individual SIP messages that are routinely aggregated into shared TCP or Stream Control Transmission Protocol (SCTP) connections. While doing so, BIG-IP products must accurately aggregate/disaggregate the triplet combinations of IP addressand port and session ID employed by SIP to identify individual sessions.

MBLB carefully preserves both the SIP message sequencing and stateful session persistence for individual VoIP calls throughout their duration. The result is improved scalability and performance of SIP servers, session border controllers, and SIP proxies by relieving them of the responsibility of performing session separation. BIG-IP devices further offload the SIP servers by performing hardware-accelerated encryption/decryption of Secure Sockets Layer (SSL) and Transport Layer Security (TLS) packets, thereby improving server performance by up to 50 percent.

By integrating these key SDN functions into the same, shared platform—along with other key features such as rate shaping, application proxying, and IP/device management—F5 BIG-IP solutions deliver a unified, single point of control for all services.

High-availability load balancing is only part of the role of BIG-IP solutions in supporting the VoIP and messaging infrastructure. SIP is fairly extensible, which can create interoperability issues between IMS services. Operating as a proxy, BIG-IP devices can transform the SIP requests and/or responses as necessary to ensure compatibility end-to-end throughout the VoIP infrastructure. With support for the Real Time Streaming Protocol (RTSP), Real-time Transport Protocol (RTP), and media gateways that interface with the public switched telephone network, BIG-IP solutions provide traffic steering services for voice and data improving Quality of Service (QoS) throughout the SDN.

BIG-IP devices offer iRules—an event-driven scripting language—to give operators additional flexibility to change how SIP messages are directed and transformed. For example, iRules could be used to proxy between an existing authentication server and a home subscriber server or other IMS service. Inspection into the SIP packet provides access tothe entire call control context, including call ID, session ID, and caller ID.

*”Mobile VOIP Demand on the Rise, Report Says”, eWeek.com