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
www.acmepacket.com
Convergence (News - Alert)
www.convergence.com
GenBand /
NextPoint (News - Alert)
Networks
www.nextpointnetworks.com
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