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Oct/Nov 2008 | Volume 3/Number 5
Featured Articles

Session Border Control and IMS — Best of Friends?

By Richard "Zippy" Grigonis
Once upon a time telecom experts wondered if SBCs would play any role in a complete IMS architecture. Obviously, they do. When it was first formulated years ago, IMS reflected the centrally-managed telecom infrastructure of the time. Now in a world of open networks, SOA, Web Services and legacy TDM, a multiplicity of network boundaries cry out for session border control to provide interworking, transcoding, monitoring and security.

One name that shows up on any list of SBC solutions vendors is Acme Packet, which recent introduced its Net-Net 4500, a new member of the Net-Net 4000 series that increases performance and capacity by 100 percent or more in SBC, Multiservice Security Gateway (MSG) and Session Routing Proxy (SRP) product configurations. Positioned between the Net-Net 4250 and Net-Net 9200 in terms of price, performance and capacity, the Net-Net 4500 targets service provider, large enterprise and contact centers and can be situated at either network access or interconnect border points.

This is all part of Acme Packet’s recent deployment of its Open Session Routing (OSR) architecture and products, and its ecosystem of companies, for delivering SIP-based interactive communications within and between mobile, fixed-line and transit networks. Acme Packet’s Net-Net Session Router and its OSR ecosystem members’ products and services operate in several tier-1 service provider networks around the world. In contrast with traditional session-stateful approaches, these solutions are designed to simplify core and internetwork session routing and reduce capital and operational expenditures as service providers transition to and further evolve their next-gen networks.

Acme Packet’s OSR architecture relies on Acme’s Net-Net Session Router (SR), a session routing proxy, working in conjunction with routing database products and services from Acme Packet OSR ecosystem members, which offer centralized routing databases and database provisioning tools for dynamic route selection. Acme Packet’s Net-Net SR, as well as the Net-Net Session Director SBC, queries the members’ databases using standard ENUM, SIP and DNS protocols. The Net-Net SR’s local route tables may also be provisioned by these members’ products or the Acme Packet Net-Net EMS using XML. Using these databases, dynamic routing decisions within the core IP network and to the PSTN and other IP networks may be made using a wide selection of parameters.

Seamus Hourihan, Vice President of Marketing and Product Management at Acme Packet, says, “We recently conducted an analysis of our own business relative to our role in IMS deployment. We probably have more experience than any other vendor on the planet. We have over 90 projects that are in various stages of progress. A good 50 percent of those are in Europe, as you might expect, followed by Asia PAC. In some cases projects are running in parallel with IMS services. For example while BT has the 21C program, it doesn’t mean that all of their voice services will run under than umbrella. In fact, they’ve got many projects that are not really under the 21C umbrella, but are services like their BT Broadband Talk that continue to generate revenue for the company. [BT Broadband Talk uses your broadband connection in the manner of an extra phone line. You plug a conventional phone into your home hub or router and dial as usual, and BT Total Broadband customers pay no extra rental.]”

Acme Packet’s Jonathan Zarkower, Director, Product Marketing, says, “If you take a look at these deployments in terms of full wireline access versus wireless access, about 50 percent are wirelinefocused. That means that the wireline vendors are looking to IMS for several reasons, such as to reduce costs as much as possible, but also hopefully set them up for new services deployment.”

“One of the new trends in the industry is driven by the service providers themselves who are looking to drive standards around the use of IMS infrastructure for IPTV,” says Zarkower. “Today IPTV standards are somewhat proprietary; Cisco, Alcatel-Lucent, Microsoft and others also have their standards or modified standards for IPTV delivery. The use of IMS — more specifically the SIP protocol — enables service providers to use a session control protocol to do such things as determine whether sufficient bandwidth exists in the network.”

“Currently, in wireless networks, in terms of the service delivery infrastructure elements, we’re still using TDM — circuitswitched voice over wireless — for the main part of it,” says Zarkower. “Some wireless providers are looking to IMS to offer additional applications such as video sharing or push-to-talk using SIP, but they’re in the minority at this time. When we finally evolve to IP-based 4G networks, there will be much greater interest in the use of at least pragmatic IMS architectures.” “Our products’ focus in the architecture is pretty much still on the scenario of service providers offering services to their subscribers,” says Zarkower. “We don’t focus as much on the ‘inner-connector’ peering side of the architecture.”

The Big Mix

Covergence was founded in 2003, to tackle the limitations that were preventing organizations from fully exploiting the abilities of real-time communications and collaboration. The Covergence Session Manager (CSM) extends functionality of the traditional SBC by enabling organizations to define, enforce, and audit finegrained security, control, routing, monitoring, and interoperability policies on VoIP, video, IM, presence, and other real-time services. CSM’s policy enforcement and auditing assures the security, reliability and quality as VoIP and real-time collaboration supplant legacy communications in enterprise and service provider networks.

Ken Kuenzel, Covergence’s CTO, says, “We see SBCs as obviously as part of an IMS architecture. I guess what we see is that IMS, in concept and in principle, is finally starting to take off with regard to telcos and carriers. As is the case with early versions of protocols and architectures, IMS is not exactly what everybody thought it was going to be. But more and more we see both our service provider and enterprise partners embracing IMS and formulating applications and moving into the telco cloud. We certainly do IMS-style interfaces but we also made considerable investments in Web Service-style interfaces too, which are increasingly becoming part of telco and enterprise architectures, as we all move from traditional computing models to Web 2.0 models, Web Services interfaces and IMS-style policy control over applications.”

“The ‘big picture’ of IMS is getting and controlling applications, and applying policy,” says Kuenzel. “You can argue about an interface here and there, or what belongs in an SBC or this network element or that element. You can pick the IMS nomenclature out of alphabet soup. But I think the ‘right’ piece of IMS is the application architecture and that’s really a distributed model. It maps onto the way the whole industry is moving. Look, in the case of anything that’s five or six years old, nobody’s got it right. No one is smart enough to come up with an endgame architecture for everything, but I think if you look at things stylistically, you see what’s getting built out, and as you drill down into the underlying technologies of what companies are doing and how they’re doing it, we find that they’re more interested in SOA [Service-Oriented Architecture]-style Web Services interfaces on the other side. Yes, there’s DIAMETER running up in the carrier clouds, and many things are SIP-based, but the infrastructure that’s often controlling things is a more traditional application infrastructure as opposed to the IMS-style DIAMETER infrastructure, although that’s still there and gaining ground. But when you look at things such as Microsoft’s Connected Framework in the telco space, or pair a BT interface and something like the Parlay standard interface [which allows Web Services to be “telecom-enabled”] you see Web Services becoming more and more part of the whole picture, and yet it overlays the IMS architecture and becomes part of it. So I think these advanced concepts will be embraced as we move forward.”

“The good thing is that those applications are becoming IMSstyle applications and the infrastructure that’s used to build it out is still a little bit ‘mushy’ and still is subject to some debate,” says Kuenzel. “But they’re building it.” “We see that some of the overall principles of the IMS architecture model, particularly the aspect of calling out a separate control plane for real-time applications, are being adopted even by large enterprises as they move to reengineer voice,” says Kuenzel. “So there’s a merging of these concepts and ideas – IMS and now concepts of cloud computing, Web 2.0, Web Services and these more common interfaces. They’re all part of the mix. This ‘fusion’ is providing both a model and set of pragmatic approaches for customers to be able to reengineer their voice networks.”

“Large telcos are very sensitive to the workings of large enterprises, as they should be, since they’re big cash cows,” says Kuenzel. “Still, the whole model is moving toward the IMS distributed application, or ‘application in the cloud’ type of model. You will have to debate what goes into it and what the protocols are, but that computational style is finally beginning to take off. It’s all jelling together. I think you’ll see over the next two or three years a sort of a ‘honing in’ regarding how all of the architectural pieces will collaborate. Where both Covergence and SBCs fit into all this is that we can support whatever comes along. We support enterprise-style policy interfaces and we also support IMS-style policy interfaces, such as DIAMETER up in the cloud, along with standard SIP methodology.”

To P-CSCF or Not to P-CSCF, that is the Question

Another company known for their SBCs was NexTone Communications of Gaithersburg, Maryland. This merged with Reef Point Systems in December 2007 to form NextPoint Networks, which in turn has recently been acquired by Plano, Texas-based GenBand, which also makes SBCs used to set up calls in VoIP networks. GenBand’s acquisition of NextPoint gives it a greater ability to compete directly with SBC makers such as Acme Packet and Starent Networks.

Just prior to GenBand’s acquisition of NextPoint, Yours Truly spoke with Aaron Sipper, Senior Director, Partner Sales, who said, “There’s clearly a need for SBCs in the network. They’re not going away. It could be that we provide the Proxy-CSCF [P-CSCF], a SIP proxy that’s the first point of contact for the IMS terminal, or the BGF [Border Gateway Functions], or we work with a partner and we’re sitting in front of their P-CSCF and our device is doing interworking. Our equipment is really positioned to work in both places, depending on what a service provider needs or what one of our partners need. The interworking between IMS and the NGN networks is still a paramount driver for us right now. We’re doing trials involving services based on voice, video, presence, IM, and so forth. One of the big debates when describing SBCs has centered on the question, ‘Is your equipment a P-CSCF?’. As it turns out, look at TISPAN, which logically broke down the SBC into the interconnect and the access SBC parts. In fact, the P-CSCF actually resolves to the broad functionality that an SBC would provide anyway.”

Mark Neider, Senior Partner and Sales Director, at NextPoint (now Genband), said, “Because we’re cost-based and COTS [Commercial Off-the-Shelf ] hardware-based, we can leverage Intel processors, such as boards in an AdvancedTCA [ATCA] form factor, or devices that will fit inside of a regular server. Thus, we can offer a server or an ATCA form factor device. Sometimes one of our partners will use that concept in multiple ways. They can take a blade and drop the SBC into their ATCA chassis, or perhaps they’re providing a P-CSCF function and we’re providing a pre-P-CSCF with some additional security to that platform. NextPoint is really very flexible in how we deploy or help our partners deploy that functionality. That’s a great advantage for NextPoint.”

“In terms of differences, it’s predominantly a software interoperability issue,” said Neider. “It’s about adding the right message sets and specific features that enable us to do IMS-to-NGN interworking and things like that. It’s not so much a hardware question, although I will say that, in working with service providers, when you look at the SBC landscape, as more features are required, be it interworking or DTMF translation or things like that, you end up having to demand more processing performance from the platform to achieve the same basic calls per second. Our solution allows operators to deliver high performance without degradation caused by the addition of features. As we deploy, our scaling abilities have become of more pronounced interest, whether it involves companies deploying straight VoIP or NGN style technology, or whether they’re looking into IMS.”

SBCs in the Saddle

One reason session border controllers remain viable is that there is no cookie-cutter set of standard SBC functions. Like IMS itself, SBCs continue to evolve to handle Quality of Service (QoS), security, interoperability and other intricacies relating to voice and multimedia services when they stream through an IP infrastructure, be it under the provenance of the service provider or enterprise.

Richard Grigonis is Executive Editor of TMC’s IP Communications Group.

Companie's Mentioned in this Article:

Acme Packet

Convergence (News - Alert)

GenBand / NextPoint (News - Alert) Networks

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