Squire Technologies DIAMETER Case Study 1 Integrating an OCS platform to facilitate 3G < > 4G Roaming -
The background to DIAMETER DIAMETER is a protocol that provides: Authentication identify the user is legitimate Authorisation What the user is allowed to do Accounting Monitoring, recording and limiting the user s usage Diameter came about in 2000 when a working group was looking for a successor to RADIUS protocol 2 DIAMETER traffic is being driven by its use in 4G / VoLTE networks, IOT, autonomous vehicles and VoIP, with the market forecasted to grow at compound annual growth rate of 44.19% from 2017 to 2023. 4G IoT (source Market Research Future)
DIAMETER background continued DIAMETER consists of a base protocol that all devices must support. Vendors, standards bodies etc RFC6733 are able to define their own interfaces for their specific applications on top of the base protocol. Underlying architecture of 4G networks is defined by 3GPP IP Multimedia Subsystem (IMS) that defines which DIAMETER interfaces are used to connect to specific network components. 3 In order to manage the flexibility of DIAMETER and the forecasted volumes of signalling data the industry has developed a set of standard DIAMETER based network products.
Diameter Signalling Controller DSC A DSC consists of 3 components. Any combination of components can be deployed in a single or distributed architecture: DRA Diameter Routing Agent for scalable centralised routing of Diameter messages in a multivendor, multi node environment within a service providers IMS core. DEA Diameter Edge Agent for secure exchange of authentication, authorisation and subscriber policy across LTE networks. 4 IWF Interworking Function provides DIAMETER to SS7 CAMEL and MAP, RADIUS insuring seamless interworking with legacy networks.
Online Charging System (OCS) Case Study We are working with a mobile operator who has deployed a state-of-the art OCS in their 4G network. The operator is at the stage where they re testing their roaming services When a subscriber roams outside the 4G network into a 3G network the OCS needs to be able to communicate with the 3G network. The OCS supports the Diameter Ro or Gy interface while all charging functions in a 3G network are handled over the legacy SS7 CAMEL protocol. 5 Pay The operator therefore needs to deploy a DIAMETER Interworking Function (IWF).
OCS Case Study continued $ Charging for pre-pay subscribers is by its very nature more complicated as there are constant checks being made to insure the subscriber has enough credit. The pre-pay subscribers in the 3G network were doing these credit checks/updates over USSD (Unstructured Supplementary Service Data) a protocol commonly used in 3G networks for billing, location based services, mobile money and menu based information services. 3G NETWORK 6 So in addition to providing CAMEL to DIAMETER there was now an additional requirement to provide USSD to DIAMETER.
Telephony Application Server IWF as with all Squire Technologies products is tightly integrated with the SVI_TAS Telephony Application Server. The SVI_TAS provides flexible API s to allow rapid deployment of new interfaces. 7 Used in this instance to provide USSD to DIAMETER interface. API
Telephony Application Server The SVI_TAS allows clients to easily and rapidly extend their service offering enabling inter-op to a range of interfacing technologies such as XML, SOAP, SQL, RADIUS, HTTP, and proprietary API s etc. Our client was able to extend functionality by utilising the HTTP interface supported on the OCS platform and implement a full USSD menu based application for their subscribers. 8 They were also able to develop the DIAMETER Ry interface to accommodate a proprietary Advice of Charge message sent over USSD.
Physical Deployment The IWF is physically deployed and embedded in a pair of DRA s (Diameter Routing Agents). The DRA s provide resiliency through redundancy, load sharing and balancing via sophisticated on-board routing. In the scenario where there is IWF node failure all on going sessions are maintained. 9 If the OCS platform is unavailable access would be granted and a CDR generated for billing reconciliation.
Optimizing for network demand As network demand increases an operator will want to launch new instances of the OCS platform. Each OCS will be configured to point its DIAMETER interface at the pair of DRA s which will automatically route messages to and from the appropriate OCS. Sophisticated load balancing can be configured so that, for example if OCS version.1 is congested then the DRA will automatically route to next available OCS. Full support for session binding insures correct online credit control is being performed when multiple simultaneous services are being billed for a single subscriber. ----- ---- ----- YouTube @ 10
Optimizing for network demand This model allows for ease of deployment in a cloud based NFV network allowing OCS resources to be easily deployed or removed as network demand dictates. NFV NETWORK 11
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