SIP network border elements typically handle SIP-specific functions such as security; NAT and FW traversal; and routing decisions within the network. Since SBCs are typically required to be transaction or call stateful, and due to the functions they are required to perform, they tend to be a single point of failure and a target for security attacks. Additionally, SBCs don’t have an external load balancing solution that views clusters of SBCs as available resources to monitor for status and load based on performance and SIP service decisions.
Scalability and Performance
Large scale deployments require systems to scale as deployment increases in a “scale as you grow” approach with complete transparency from the carrier and user perspective. This approach requires both the option to add more servers to scale the system and to offload traffic between locations. Additionally, performance acceleration is of the essence to increase system capacity and thus increase ROI. Answering this need requires a SIP-aware solution that can handle session persistency based on varying SIP parameters as well as transport and security offload from core network mission-critical components to accelerate traffic handling.
High Availability, Fail-over and Disaster Recovery
High availability and system resilience are key and mandatory requirements for deployment of mission-critical SIP border elements in carrier networks. These capabilities are implemented not only in the scope of the actual product but require both a local and global system view (multi location view). Carriers expect such products to be easily scalable and support high availability and resilience features such as local and global server clustering, mid-call failure recovery and health monitoring for servers and services. Current solutions available for solving these challenges are limited to non SIP-aware external solutions that don’t provide a comprehensive solution beyond the layer 4 scope.
Security
Deploying the application in the network exposes it to security threats such as DoS/DDoS attacks, worms and other SIP vulnerabilities. Floods of unsolicited SIP messages can easily consume CPU resources of the SIP servers. Similarly, state management of UDP packet floods can hog bandwidth resources and degrade voice and video service quality. Even though border elements are aware of such threats they are at the same time a target for them. This imposes significant load and risk on the mission critical border element. Therefore, offload of this requirement to an external solution is required to reach higher capacity and performance saving slots in its system which in turn increases ROI.