As LTE and IMS networks proliferate, so does the need for roaming and interworking between MNOs. Whether through direct interworking with adjacent networks or via intermediary roaming hubs, there is a quickly accelerating requirement for Public Land Mobile Network (PLMN) interworking which is addressed by the IR.88 LTE Roaming Guidelines specification and its definition of the Diameter Edge Agent (DEA). In addition, critical requirements for security, accounting, and interoperability must be considered.
The DSC addresses the Edge Router use case. It provides configurable security, edge agent functionality, the ability to enforce inter-operator SLAs, and compensation for variances in message content and format through use of advanced scripting technology. The DSC addresses both generic LTE routing and LTE Legacy Interworking as described in GSMA PRD IR.88 and 3GPP TS 29.305.
As the MNOs shift to LTE access technology and the corresponding EPC (Evolved Packet Core), inter-MNO roaming is required. Roaming presents a number of challenges that must be addressed.
Interworking – Basic interworking, as described in GSMA’s IR.88 specification, must be supplied.
Interoperability – Mobile Network Operators typically deploy different equipment, with different interpretations of the standards, and at different implementation and standards levels. Enabling interoperability between these variants is also an essential part of the operator’s requirement. Significant levels of testing effort can be required to ensure smooth operation as new inter-MNO connections are introduced.
Security – As the MNOs interconnect their networks, each network must be protected from the other from both a malicious and an accidental damage perspective. Further, both must be protected from outside attacks. The use of encryption becomes an essential first barrier. Content-based monitoring and restriction mechanisms become second level barriers in order to prevent unauthorized service and data access and to enforce service level agreements between MNOs.
Service Level Agreement Support – MNOs will deploy the roaming capability under conditions of SLAs. These agreements will have features, such as total traffic throughput limitations and charging requirements that will require direct support in the Edge Agent.
Routing – MNOs will require a variety of routing capabilities at the network boundary to fulfill differences in applications and relationships with other MNOs. Included in these requirements are realm-based routing, IMSI-based routing, and routing based upon the content of one or more AVPs in a message.
TOPOLOGY HIDING – An important aspect of inter-MNO operation is cooperation without disclosure of competitive information. Topology hiding prevents inadvertent disclosure of proprietary information such as network addresses at a boundary as well as removing opportunities for inadvertent access to restricted network elements.
The DSC Solution
The DSC provides Edge Routing capability exceeding the basic functionality specified in the IR.88 standard, and addressing the challenges of operation in support of both Mobile Network Operators and Roaming Hub operators.
The DSC provides a scripting mechanism that can compensate for differences in interpretation of standards and standard levels in real-time. This mechanism can examine and modify any part of a message to compensate for differences as needed.
The DSC provides IPSEC and TLS encryption support, providing the first layer of defense for malicious attacks. The DSC also provides for White-List and Black-List security controls – enabling MNOs to control who can access their network and limiting access to only those devices that are preauthorized.
The DSC provides features to enable SLA support. In addition to security features, and ad hoc enforcement via scripting, the DSC provides for limits on total traffic throughput at the Edge Routing boundary and provides for Call Detail Record (CDR) generation to charge for roaming activities.
Learn more about DSC.