As more users migrate to LTE networks supported by Internet Media Subsystem underpinnings, mobile operators have to deal with a rise in diameter signaling traffic.
Cisco has reported that global mobile data traffic grew by 69% in 2014, and 26% of global wireless connections – including machine-to-machine – are expected to be on LTE networks by 2019, up from 6% last year. Industry observers and vendors have been anticipating the impact (or hype) of LTE-related “signaling storms” for some time. Oracle noted in a white paper that signaling storms can come from two directions: radio frequency signaling that can gum up the Radio Access Network, and diameter signaling in the core network.
Ben Volkow of F5 has cited a number of reasons, including traffic growth, the evolution to all-IP networks and the fragmentation of networks, as driving the need for diameter signaling management. Those needs have led vendors including Ericsson, Sonus, Dialogic, Tekelec and more to introduce diameter-related solutions such as the Diameter Signaling Controller as an aggregation point for diameter signaling within mobile networks; and the Diameter Signaling Router. Part of the reason is also that there is more messaging involved in diameter than in predecessor SS7 networks, according to John Baker, GM of Spirent’s mobility business.
“In terms of the number of messages, just setting up a phone call is probably four to five times that of what was on a SS7 network,” said Baker. Spirent is jumping in to address the growth of diameter signaling with a new mechanism for stress-testing diameter capacity within networks. Baker said that the amount of signaling impacts the capacity of the Internet links in networks, and that operators need better insight into just how much “signaling overhead” they need when thinking about the network connection capacity they are purchasing or installing.
“The concern is, you’ve got a heavy signaling load already, and you put buggy apps on top of that, and suddenly you don’t know where you are” in terms of network functionality, Baker said. The diameter protocol is responsible for authentication, authorization, accounting, policy and charging and mobility management in LTE networks, expanding its 3G role in policy and charging – meaning that issues with diameter not only have the potential for slow networks or dropped connections, but lost billing information.
“There is a direct correlation between diameter traffic and data revenue,” according to Cisco. “As service providers begin to monetize their IP networks, the volume of diameter signaling increases.”
Baker said that the new Landslide solution from Spirent is “essentially a load tester for all the elements in the network” that enables the loading of diameter interfaces across a network through either the use of Landslide as a network emulator or in using it to inject mobile handset traffic into a real platform; such capabilities have not previously been available in the testing market, according to Baker. It also includes the ability to test virtual diameter interfaces, he added, with the expectation that such interfaces will be used in roaming scenarios.
In the past, Baker added, operators often focused on the basics of building functional network connections between new networks — now the connections continue to be important, but the size of the pipe and the proper, efficient routing of traffic that can traverse multiple service providers while maintaining service level agreements.
“As more operators deploy LTE, VoLTE, and enhanced IP services, the amount of diameter messages within and between operators is growing. Optimizing the signaling plane has become a necessity,” said Diane Myers, principal analyst of Infonetics, part of IHS, in a statement.
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