Pipeline Publishing | OSS and BSS News and Info

Pipeline Publishing, Volume 7, Issue 10

	This Month's Issue:
	Unlocking Next Gen Networks

The road to LTE is paved with Diameter

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Network interconnect: A fully meshed network may expose the operator’s network topology to other operators and could lead to security breaches because there is no central interconnect point.
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. IOT activities consume a considerable amount of operator time and resources, with costs increasing in proportion to the number of tests that must be performed.
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. With no separate Diameter signaling infrastructure, that task must be handled by a standalone subscription locator function (SLF), or by the HSS itself. Either approach wastes MME (or call session control function [CSCF]) processing and can add unnecessary delays. The HSS approach wastes HSS resources and may even result in the need for more HSSs than would otherwise be necessary.
Policy and charging rules function (PCRF) binding: When multiple PCRFs are required in the network, there must be a way to ensure that all messages associated with a user’s particular IP connectivity access network (IP-CAN) session are processed by the same PCRF.

Operators used to managing SS7 networks also should know that certain “common rules” no longer apply in LTE, and they will need to take other measures to get the same network behavior as with SS7.

Centralizing Diameter routing reduces the cost and complexity of the core network.

One example is network failures. In SS7, the network is designed and configured to route around a failed path, and the signaling is optimized upon detection of a failure. For Diameter, the failed path must be re-discovered every time a request is sent over the network. In this example, Diameter signaling is less efficient.

The Need for Centralized Routing

Centralizing Diameter routing reduces the cost and complexity of the core network and enables core networks to grow incrementally to support increasing service and traffic demands. A centralized node can then proxy information for decentralized elements like HSSs, MMEs or PCRFs.

When connecting to a Diameter-based network element in another operator’s network, there is always the risk that the Diameter implementations will not match perfectly, even if the elements are provided by the same vendor. Therefore, a Diameter agent is required to adapt Diameter messaging. By implementing the functionality at the central network core level, operators can perform IOTs faster and more cost effectively.

Tekelec’s Diameter Signaling Router (DSR) creates a centralized core Diameter signaling layer that relieves LTE and IMS endpoints of routing, traffic management, and load balancing tasks and provides a single interconnect point to other networks. Each endpoint only needs one connection to a DSR to gain access to all other Diameter destinations reachable by the DSR. This approach eliminates the Diameter/SCTP (or TCP) mesh that is created by having direct signaling connections between each network element. Having one or more SCTP hubs that centralize the SCTP connections to all end nodes simplifies interoperability between different network elements and enhances network scalability.

The path to 4G is evident. As operators move to LTE, centralized Diameter signaling can help them better manage costs and the scalability of the network.

About Tekelec: Tekelec, the broadband data management company, enables billions of people and devices to surf, talk, and text. Our solutions allow service providers to give consumers a consistent and tailored broadband experience. We handle network complexity with a portfolio that manages and capitalizes on the exponential growth in data applications and traffic. Tekelec has more than 25 offices around the world serving customers in more than 100 countries.

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