Editor’s Note: Welcome to our weekly Reality Check column. We’ve gathered a group of visionaries and veterans in the mobile industry to give their insights into the marketplace.
The rise of Diameter traffic is analogous to the early days of SS7 traffic growth. In the 90s, service providers began struggling with an exponentially growing mesh of SS7 connections as they added more equipment to support subscriber growth. The solution was to standardize around a core routing function called the signal transfer point to create a reliable, scalable SS7 network.
The result was an architecture that lowered operating costs, supported multiple interfaces and industry standards and provided flexible configurations. This permitted service providers to cost-effectively grow their networks and work with one another on essential capabilities such as subscriber roaming and the delivery of revenue-generating services.
Today, operators are starting to see the complications of deploying Diameter-based elements in next generation networks. Mobile data usage is generating an explosion of policy, charging and authentication traffic in 3G networks which will accelerate when mobility management becomes Diameter-based in 4G LTE and IMS networks. Diameter traffic underpins each of these network functions, but vendors implementing Diameter on individual network elements haven’t focused on the effects of Diameter traffic on the network as a whole.
Therefore, key network management functions are lacking, such as congestion management, link failure detection and alternate routing. In addition, there’s little ability to troubleshoot Diameter networks to understand subscriber, device and network activities. And unlike SS7 networks, the industry has not yet fully standardized on a single architecture to manage all of this traffic. But thanks to the STP, the industry has a precedent.
The Diameter router
A Diameter signaling router replicates many of the STP’s functions and can be used to create a core network layer dedicated to Diameter traffic. At a high level, a DSR offloads Diameter routing functions from endpoints and places them in a central location. This new network element connects with mobile management entity, home subscriber servers, policy and charging rules functions, and online and offline charging systems, among other equipment.
When new equipment is added to networks, operators only have to update routing logic in the diameter signaling router, instead of at each endpoint. Further, the DSR mediates different Diameter variants regardless of the vendor and various protocol extensions, giving operators the ability to create a network comprised of best-of-breed products.
Specific core network functions include:
–Routing: The DSR provides a 3GPP-compliant Diameter Relay Agent to forward messages to the appropriate destination based on information contained within the message, including header information and applicable attribute value pairs. Functions of the relay agent include: Routing to Diameter peers based upon user-defined message content rules, priorities and weights; alternate routing on connection failures, answer timeouts or user-defined answer responses; and route management based on peer transport connection status changes or Oracle access manager configuration changes.
–Load balancing: In addition to the basic DRA function, the DSR supports the concepts of routes, route groups and route lists to provide a very powerful and flexible load balancing solution. Priorities and weights can be assigned to optimize and manage the flow of traffic through the network.
–Congestion control: The DSR supports local congestion control via the use of congestion levels. Congestion levels are defined where only a percentage of request messages will be processed during the congestion period. Congestion levels correspond to minor, major and critical alarms associated with resource utilization. Remote congestion control is implemented using communication between the DSR and its peers. This is designed to inform the DSR of the peer network element’s level of congestion, enabling the DSR to implement alternate routing to avoid the congested peer.
–Centralized Diameter troubleshooting: With its location in the core of the Diameter network, the DSR offers the perfect vantage point from which to collect network traffic and subscriber data for troubleshooting, managing traffic, roamers, services and revenue. The DSR provides the following functions: Filtering on xDR content, covering detail records for all subscriber activity; online and offline viewing of system generated message traces; alarm forwarding for signaling and system alarms; data feed to a centralized monitoring system; and monitoring of Internet protocol security-encrypted traffic.
The Diameter router has the opportunity to replicate the functionality and value of the STP in next-generation networks. Just as the STP solved an emerging problem two decades ago, a Diameter router brings simplicity, reliability and flexibility to operators, offering cost savings and the ability to more easily generate revenue.
Jason Emery (@jgemery ) is Director of Product Management at Tekelec. He has more than 20 years of next-generation signaling experience, and has authored or co-authored more than 10 U.S. patents and invention disclosures.
