SIP core network products such as IMS x-CSCFs and pre-IMS softswitches reside in the heart of the carrier’s and operator’s network and thus are mission-critical entities. This in turn imposes strict requirements on TEMs developing these solutions.
Interoperability and Constant Standard Updates
Even though SIP is an IETF standard defined in RFC 3261 there are many extensions and implementations of the protocol. Extensions include support for IMS (3GPP & TISPAN) as well as support for more advanced features and services. Additionally, SIP continues to constantly be extended and modified in the standard bodies, requiring constant follow-up, short cycle product updates, and frequent interoperability validation. This requires R&D centers to be extremely flexible in order to facilitate short cycles for new feature developments and modifications. This contradicts the common development practice of TEMs and vendors for these types of solutions.
Core network products impose greater interoperability and feature support requirements as they reside in the heart of the network and are required to communicate with all of the SIP entity types of multiple vendors.
High Availability, Fail-over and Disaster Recovery
High availability and system resilience are mandatory requirements for deployment of core network products 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 products in their core network to support high availability and resilience features such as local and global server clustering, mid-call failure recovery and health monitoring of 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.
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 depending on peak time needs. 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.
Time-to-Market
Building a solution that solves the challenges of high availability, resilience, scalability and security will usually result in a long development cycle, which in turn causes delays in the release of products to market. Core network solution providers (TEMs and vendors) are looking for ways to reduce time-to-market cycles and minimize development investment.