The IP Multimedia Subsystem (IMS) is finally ready to deliver on the promise of ubiquitous VoLTE and converged rich communications services; but to fully realize the potential, network operators must think beyond simple virtualized network functions to fully cloud native IMS components.
Clearwater Core is Metaswitch’s implementation of IMS built exclusively using web development methods to provide voice, video and messaging services to millions of users or IoT endpoints. Architected from the ground up for massively scalable deployments within virtualized public, private or hybrid elastic compute clouds, Clearwater Core combines the economics of over-the-top (OTT) style service platforms with the standards compliance and reliability expected of telco-grade network solutions. The web services-oriented design, along with the component-centric micro services philosophies adopted when architecting Clearwater Core, makes it ideal for instantiation within either hardware VM-based hypervisor infrastructures (VMware or KVM) or emerging OS container-based (Docker) environments with (Swarm or Kubernetes) Cluster management.
Clearwater Core comprises all key IMS elements, including the I-CSCF, S-CSCF and BGCF. A Charging Collection Function (CCF) converts Rf-based billing streams into file-based CDRs while the HSS Mirror eliminates unnecessary queries of the global user database. Network operators can also deploy Clearwater Core in conjunction with other IMS components from Metaswitch, such as the Perimeta Session Border Controller (SBC) and our Access/Media Gateway Control Functions (A/MGCF). Clearwater Core works with the MetaView network management system - including the Service Assurance Server (SAS) - to present alarm monitoring, statistics and analytics.
When designing Clearwater Core, Metaswitch adapted web design principles to fit the requirements of SIP and IMS so that Clearwater Core could deliver dynamic, granular, elastic scalability and unmatched resilience even in IT-grade cloud infrastructures. Clearwater Core’s components scale individually using our unique stateless load-balancing techniques; it does not store long-lived states on individual nodes, which avoids the need for complex data replication schemes. Following the trend in innovative internet software architectures, Clearwater Core’s interfaces between the front-end SIP components and the back-end services use RESTful web services APIs while interfaces between the various components use connection pooling with statistical recycling of connections. This guarantees that traffic loads are spread evenly as nodes are added and removed from each layer.
Clearwater Core supports the management and orchestration options that are critical in software-defined service function chains built on NFV constructs. It works with a wide range of independent and open VNF managers plus management and orchestration (MANO) lifecycle operations anchored by OpenStack. This includes instantiation, configuration, startup, clustering, quiescing and termination.
Having now been live for twelve months, Perimeta and Clearwater have both been rock solid. Manx Telecom have a tradition of firsts, first 3G network in Europe, first fully digital telephone network in Europe, and we are glad we continued with that drive for innovation by selecting Metaswitch to provide our virtualized IMS core.