Tekelec product manager, Jason Emery, spoke with Telecom Engine on Diameter routing and how the Diameter Signaling Router (DSR) product supports multiple networks, including LTE, through the centralization of routing, traffic management and load-balancing tasks:
TelecomEngine: How is the Diameter Signaling Router (DSR) applicable for both LTE and 3G networks?
Jason Emery: The Diameter Signaling Router has five different categories of use cases, and of the five use cases there are three that are particularly applicable to both LTE and 3G networks: charging proxy, policy proxy and core routing.
The charging proxy functionality is a load balancing, topology hiding and session binding capability that operators place in the middle of their offline or online charging solutions. Topology hiding masks the address of the end server from the server that’s connecting to it. For example, if a gateway has a subscriber attached to it, it doesn’t need to know the address of a charging server in the network. It only has to know the address of the DSR. The DSR then picks a charging server to serve that gateway and by doing that operators reduce opex because they don’t have to constantly update all of the gateways in the network with the charging server addresses. It also does load balancing, which is picking a server to deliver the charging information. The last task in this use case is session binding, which makes sure that once a charging server is selected, all the billing records about an individual session go to the same charging server. This is important to eliminate a lot of post processing of billing information that would otherwise have to happen.
Senior Product Manager Susan Hackman provides a brief update on the Diameter Signaling Router, including Tekelec’s win with Verizon Wireless and the Diameter Learning Center.
Director of Product Management Jason Emery discusses 3G use cases for Diameter routing in his latest “Reality Check” column for RCR Wireless, including offline charging proxy and policy server load distribution and session binding. Excerpt:
“The 3GPP specifies the Rf Diameter interface for offline charging. In the 3GPP model, the charging trigger, which can reside in a number of network elements including gateway GPRS support nodes (GGSNs) and signaling gateways (SGs), is directly connected to offline charging systems (OFCSs). In real networks, there may be many SGSNs, SGs and OFCSs. As the network grows, the mesh-like architecture created by the direct connections between the elements becomes more unreliable and increasingly difficult to manage.
Without a centralized Diameter routing infrastructure, the SGSNs and SGs must support load distribution and failover for Diameter messages toward the charging servers. Operators must also independently test the same failover models on each client type added to the network, a costly approach that delays time to market.”
Are you interested in learning more about Diameter? Diameter is the signaling protocol used predominantly in operators’ all-data networks for policy, charging, mobility management and IMS functions. While it’s considered a key next-generation signaling protocol, how to implement and deploy Diameter networks isn’t well defined and education is needed in the industry to make the best implementation and deployment decisions.
As a key provider of the next generation of signaling infrastructure, Tekelec has created an online learning center focused around the Diameter protocol. The Diameter Learning Center is your go-to resource for all things Diameter, including whitepapers, on-demand webinars and the latest industry trends and news.
The center will be frequently updated so be sure to check back regularly. If you have any suggestions as to how we can improve the center, please contact us.
Dramatic growth in mobile data traffic, fueled by the proliferation of data-enabled devices and applications, is creating a byproduct many 3G operators haven’t anticipated – a surge in Diameter signaling, which provides the framework for policy, charging and authentication functions. Diameter, using transmission control protocol (TCP) and stream control transmission protocol (SCTP) for transport, serves as the interface between numerous network resources. Without a separate Diameter signaling core, each endpoint must have a direct TCP connection or SCTP association with every element to which it is connected. These point-to-point connections form a mesh-like architecture in which each resource must handle all session-related tasks. As Diameter signaling swells, scalability, network management, protocol mediation, and interoperability testing (IOT) challenges develop. These challenges will multiply in 4G networks, which rely heavily on Diameter protocol.
Tekelec recently released a brief that reviews three use cases for Diameter signaling:
Offline Charging Proxy
Online Charging System (OCS) Load Balancing
Policy Server Load Distribution and Session Binding.
Tekelec’s Diameter Signaling Router is a world class solution with many substantial benefits. Tekelec’s Susan Hackman and Sridhar Karuturi explain how the DSR differs from competitors’ solutions.
Tekelec’s Diameter Signaling Router (DSR) has been named a finalist for ‘Best New Product or Service of the Year’ by the 2011 American Business Awards (aka the Stevie Awards). Vote for the Tekelec DSR by visiting the People’s Choice Stevie Awards and entering short code T238L. Voting ends June 3.
The Tekelec DSR product centralizes routing, traffic management and load-balancing tasks to create an architecture that enables your IMS and LTE networks to grow incrementally to support increasing service and traffic demands. And, as the first point of contact at the network’s edge, the DSR is the ideal vantage point from which to defend your network against potential overloads or attacks. It can be deployed as an IETF Diameter Agent, 3GPP Diameter Routing Agent (DRA) or GSMA Diameter Edge Agent (DEA).
For more information on the DSR, explore the links below.
The Diameter protocol is widely used in 3G, IMS and LTE architectures to transport policy, charging, authentication and mobility management messages – traffic that will rapidly rise as mobile data usage increases.
To best manage the growth of Diameter traffic, operators are examining how to create a separate Diameter signaling infrastructure at the network core. The goal is to facilitate signaling between network elements, eliminating a mesh-like architecture of direct connections between endpoints such as mobility management entities (MMEs) and home subscriber servers (HSSs). This would relieve endpoints of handling all session-related tasks such as routing, load balancing, congestion control and failover management.
Initially, implementing an IMS or LTE network without a signaling core may be sufficient, but as traffic levels grow, the lack of a capable signaling infrastructure poses a number of challenges, including:
Scalability: Each endpoint must maintain a separate SCTP association with each of its Diameter peers as well as the status of each, placing a heavy burden on the endpoints as the number of nodes grows.
Congestion control: Diameter lacks the well-defined congestion control mechanisms found in other protocols such as SS7.
Protocol mediation: Vendors are likely to use their own variants of the Diameter protocol based on how they believe a specific interface should be implemented. This implementation can vary slightly from those of another vendor, creating potential interworking issues when multi-vendor equipment is combined in one network, a common approach for operators that take a best-of-breed approach.
Network interconnect: A fully meshed network is completely unworkable when dealing with connections to other networks because there is no central interconnect point. This also exposes the operator’s network topology to other operators and can lead to security breaches.
Interoperability testing (IOT): Protocol interworking becomes unmanageable as the number of devices supplied by multiple vendors increases. With no separate signaling or session framework, IOTs must be performed at every existing node when a new node or software load is placed in service.
Support for both SCTP- and transmission control protocol (TCP)-based implementations: SCTP-based elements cannot communicate with TCP-based elements unless they are upgraded or all of the elements support both protocol stacks.
Subscriber to HSS mapping: When there are multiple HSSs in the network, subscribers may be homed on different HSSs. Therefore, there must be some function in the network that maps subscriber identities to HSSs.
Policy and charging rules function (PCRF) binding: When networks require multiple PCRFs, operators must have a way to ensure that all messages and sessions associated with a particular user are processed by the same PCRF.
Centralizing Diameter routing creates a signaling architecture that reduces the cost and complexity of the core network and enables core networks to grow incrementally to support increasing service and traffic demands. It also facilitates network monitoring by providing a centralized vantage point in the signaling network. A centralized Diameter router is also the ideal place to add other advanced network functionalities like address resolution, Diameter interworking and traffic (roaming) steering.
