The VoIP Peering Puzzle�Part 53: SBC Architectures�U4EA Technologies

U4EA Technologies—pronounced euphoria and headquartered in Fremont, California, with facilities in Nice, France and Bristol, UK, and manufacturing in Shenzen, China—is a privately-held company with a great deal of experience developing systems that support high quality voice transmissions. So experienced, in fact, that they have developed their product around a process that the company calls Guarantee of Service, or GoS™. The word guarantee seems like a lofty claim to make, so let’s peek under the hood and see what this technology is all about.

Transporting real time traffic within a data network has some significant challenges, principally because it is difficult to retransmit a garbled message and still keep the end-to-end delay within a reasonable limit, such as the 150 millisecond maximum delay that is frequently specified. And adding to that challenge is that this 150 millisecond figure represents the total delay, which includes both the carrier portion and the end-user hardware, plus any additional systems that might also be in the path from the source to the destination—some of which the carrier can control, and some of which it can’t.

In the last few years, many vendors and standards organizations have developed Quality of Service (QoS) mechanisms that attempt to minimize this delay, seeking to provide a voice call via a packet network that rivals the quality of the PSTN. Algorithms such as Integrated Services, Differentiated Services, Weighted Fair Queuing, Random Early Detection, and others have been debated by vendors and network managers for several years, with most everyone having a favorite.

U4Ea’s view, however, is that these traditional QoS mechanisms only have three options for arriving packets: They can transmit the packet immediately (and risk blocking the link), they can queue the packet for later transmission (and risk increasing the delay), or they can discard the packet (and increase the packet loss).

The U4EA approach builds a mathematical model that generates a relationship between packet throughput, delay, and loss. Once one of these parameters is specified, the other two can be predicted. U4EA’s system operates by dividing the incoming traffic into what they call Quality Groups, which can then be policed and shaped to enforce bandwidth requirements. The guarantee results from the statistical model that predicts the result.

U4EA’s flagship product is named the ICAD 40 Business Gateway, an all-in-one router, session controller, and gateway that is designed to allow carriers to deliver converged services to small and medium enterprise (SME) customers. In addition to providing a demarcation point between the carrier and customer networks, the gateway offers a mechanism to effectively manage the real-time IP communication, and measure the service level agreement (SLA), or operational efficiency of the link between those two networks. That mechanism is based upon U4EA’s GoS system.

The ICAD 40 incorporates a number of key features that that support voice, video, and data transport connections.

First, the product incorporates a MGCP/SIP session controller that allows end users to establish policies for VoIP calls. The controller has a capacity to handle up to 500 concurrent calls, with call rates exceeding 20 calls per second. The session controller also interacts with internal firewall and network address translation (NAT) functions, thus providing protection for the VoIP sessions. The session controller can also switch local calls, so that inter-office calls can still be placed even if the WAN link has gone down. In addition, emergency calls can be switched to a backup FXO (foreign exchange office) line.

However, the session controller’s integration with the QoS mechanism is perhaps the product’s real distinguishing feature, as the bandwidth allocation can be determined by the current call requirements. This is designed to guarantee that the call sessions receive the network bandwidth that they need, and that other high priority traffic does not interfere. For example, the system will returns a busy signal if it determines that a WAN link’s capacity would be exceeded by allowing an additional call.

The system’s network management capabilities are also especially strong, and include the ability to monitor every call, and generate voice quality reports after calls complete. A number of call statistics are generated and available for export, including standard scores of the Perceptual Speech Quality Measure (PSQM, defined in ITU-T Recommendation P.861), Mean Opinion Score (MOS, defined in ITU-T Recommendation P.800), and the R-Factor (a multi-parameter transmission rating factor defined as part of the E-Model in ITU-T Recommendation G.107). The system also supports the Simple Network Management Protocol (SNMP) to facilitate integration with other network management systems.

The ICAD 40 is packaged in a form factor about the size of a large book, and is equipped with two telephony, one WAN and two LAN ports, with an external serial interface to a console. Further details on the U4EA architecture and products can be found at |}{ Our next tutorial will continue our examination of vendors’ SBC architectures.

Copyright Acknowledgement: © 2007 DigiNet Corporation ®, All Rights Reserved

Author’s Biography
Mark A. Miller, P.E., is President of DigiNet Corporation®, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including Voice over IP Technologies, and Internet Technologies Handbook, both published by John Wiley & Sons.

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