Solution Overview

With the growth of LTE devices, the increased number of interfaces in the EPC (Evolved Packet Core) network, and the migration of SS7 signaling to Diameter, the number of Diameter messages in the EPC network has greatly increased. This growth has led to the need for carrier-grade infrastructure to support the scalability and reliability of the Diameter protocol in the EPC network. For the SS7 network, the STP (Signal Transfer Point) node was used to support carrier-grade infrastructure. For the Diameter protocol, the Diameter Signaling Controller (DSC) is used to provide a similar infrastructure in the EPC network.

The growth of traffic at unpredictable rates coupled with the rapid pace of network deployment (LTE Long Term Evolution) is producing a fundamental shift in the core network from SS7 signaling to Diameter signaling. This situation has led to a new class of products called DSCs (Diameter Signaling Controllers), which are associated with growth and expected load through efficiently routed signaling traffic.

Just as important as the STP node for SS7 networks, the DSC node has become critical to support Diameter signaling.

The Diameter Routing Engine™ (DRE) includes the Diameter DRA (Diameter Routing Agent), the Diameter DEA (Diameter Edge Agent). These functions can be configured according to network requirements.


In addition to reducing Diameter signaling in the underlying network, the Diameter Routing Engine provides many other benefits to the network:

Application SelectionThe DRE allows users to write their own applications and integrate them into the DRE platform.
Congestion ManagementLocal and remote congestion can be detected and traffic can be rerouted or discarded to overcome peak traffic conditions. This improves the quality of service on the network.
Improved balancingDiameter message routing rules can be configured using any AVP from the Diameter message, providing complete flexibility in server selection in a distributed network.
Support for cross-release conversionsClients and servers from different vendors may support different releases and versions of Diameter interfaces. Therefore, it should be possible to provide rule-based compatibility.
Interoperability functionalityDRE provides interoperability functionality for the diameter and SS7 protocols, which can be dynamically changed via scripts or plugins.
Load balancingLoad balancing of messages using multiple AVPs across multiple instances of the same server provides the ability to distribute traffic and provides scalability.
Performance and scalabilityVery high performance with minimal latency and scalability within a single site, and the ability to distribute the solution across multiple sites allows the network to scale continuously.
ReliabilityHigh availability within a single site and multi-site geo-redundancy in the event of a site failure ensures the reliability of Diameter signaling. Thus, it facilitates network scaling, reducing necessary time and risk.
SecurityTLS support allows secure access to Diameter signaling, and therefore protects the network from untrusted domains.
Session bindingDiameter messages are routed to the same PCRF contained in routing information stored in the subscriber terminal or PDN packet data network, providing scalability.

Solution for operators

The deployment of 4G LTE networks is under strong price and time pressure due to the rapid and widespread growth of Diameter traffic. However, with any new technology comes several challenges for mobile operators. Service providers must overcome these challenges to provide reliable services.

Traffic Management

A centralized signaling management system that controls the growth and complexity of Diameter messages in a mobile operator's network is indispensable. Diameter interfaces are point-to-point interfaces without centralized management. This results in a meshed organization with no scalability or low network reliability, leading to potential traffic congestion and network problems.

Traffic control

DRE functions as a Diameter Routing Agent and provides:

  • Flexible load balancing to maximize server utilization with failover and failback mechanisms
  • Advanced routing to provide flexible network configuration and independent scalability for clients and servers
  • Session bindings and congestion control with diameter throttling mechanism


Diameter interfaces need to secure and conceal the topology of Diameter internal servers. Ensuring security in inter-operator networks is a major challenge for mobile network operators.


DRE, which functions as a DEA (Diameter Edge Agent), provides security at several levels, including TLS (Transport Layer Security), IPsec (Internet Protocol Security), firewall and access control lists. It acts as the entry point to the home LTE network and supports all Diameter interfaces from the guest LTE network. Security is provided over all untrusted domains, and the guest network does not need the home network topology information. Home networks can scale and reconfigure without affecting guest network configuration.

Vendor Compatibility

EPC (Evolved Packet Core) provides an architecture that allows a user to connect to a network via multiple vendors supporting different protocol versions. Different vendors may also implement the standard differently. They may also have non-standard specific implementations. It is important for the operator to have confidence in the compatibility of EPC components in a multivendor environment.


DRE provides a flexible Diameter conversion capability to adapt to non-standard Diameter releases. Diameter interfaces can be dynamically modified via scripts or plugins. DRE, acting as a Diameter Translation Agent (TLA), allows adding, deleting, modifying, regrouping, or rearranging AVPs (Attribute Value Pairs). Conversions can be performed at the point-to-point level. Operators can control the integration of 3-party clients and servers, especially for roaming, where there is no vendor control.

Compatibility with legacy networks

4G networks need to interoperate with 3G networks, but not all carriers are migrating to 4G at the same time, leading to hybrid 3G and 4G network elements.

Legacy network compatibility

DRE in IWF (Diameter Interworking Function) mode provides Diameter and SS7 interworking functionality which can be dynamically modified via scripts or plugins. It supports MAP to/from Diameter (e.g., S6a, S6d, S13, S13' to GSM MAP and ANSI-41 MAP) and CAP/WIN to/from Diameter (e.g., Gy, Ro to CAP and IS-826 WIN) conversions. The DRE interfaces with existing equipment in 2G/3G and uses them in the 4G network, allowing roaming with carriers that have not yet migrated to 4G.

Migration of services

It is a definite challenge for operators to adopt the safest and smoothest migration path. For example, this is the case when migrating from 2G/3G services based on SS7 (using GSM/ANSI41 MAP,CAP or WIN protocols) to 4G LTE network services. It is most likely that 4G network interaction with 3G networks will be required, since not all operators are migrating to 4G at the same time, resulting in hybrid 3G and 4G network elements.

Service migration

DRE, performing the IWF (Diameter Interworking Function), provides interworking functionality for Diameter and SS7 protocols, which can be dynamically modified using scripts or plugins. Conversion of the MAP (Mobile Application Part) protocol to/from Diameter (S6a, S6d, S13, S13' to GSM MAP and ANSI-41 MAP) and CAP/WIN to and from Diameter (Gy, Ro to CAP and IS-826 WIN) is supported. DRE supports the existing capital investment (CAPEX) in 2G/3G elements and allows them to be used for the 4G network, allowing roaming with carriers that have not yet moved to the 4G network.


Security is a major consideration when launching any 4G service, primarily for those calls that involve roaming on other networks. Operators must be careful when exposing their nodes to outside entities.

When DRE is deployed in the underlying network, it acts as an entry security point. In this configuration, DRE provides security mechanisms such as TLS (Transport Layer Security) and IPsec (Internet Protocol Security), which provide only authorized access to the network.


The DRE application provides the following functionality:

  • Flexible rule-based routing using configurable AVPs with modification
  • High availability (HA) solution at a single site provides at least 99.999% reliability
  • Geographic Redundant (GR) solution across multiple sites for disaster recovery capability
  • Capacity up to 100K messages/sec per server/blade
  • Scalability up to 1M messages/sec per cluster
  • Advanced routing and load balancing
  • Application selection feature
  • Diameter protocol conversion feature
  • Session tracing with configurable filter rules using AVPs or combinations of AVPs
  • Binding sessions with routing protocol messages to the same PCRF according to routing information stored in the subscriber's terminal or packet PDN

DRE Benefits

DRE has the following operator benefits:

  • Simplification of routing and provision of advanced protocol traffic load balancing
  • Ability to design a highly complex environment to meet interoperability requirements
  • Cluster architecture providing high availability of the solution
  • Providing easy-to-use, centralized OA &M (Operations, Administration and Maintenance) functionality with a graphical user interface (GUI) to manage incidents, configuration, statistics and reports
  • Ability to use legacy network elements
  • Provides network protection against untrusted domains