More MSOs are about to jump on the early deployment
bandwagon in IP telephony, even though new developments are complicating the process of
developing standards for cable in this area.
That's the word from officials of the former Bell
Communications Research (Bellcore), which announced a new name for itself last week,
Telcordia Technologies Inc., in keeping with stipulations deriving from its purchase by
Science Applications International Corp. from the Baby Bells two years ago.
"We're seeing tremendous demand for this
technology from cable companies in Canada, the United States, Europe and other parts of
the world," said Sanjiv Ahuja, president and chief operating officer of Telcordia.
"We believe that customers are very happy with the
features, functionality and interfaces that are part of the system that we're
delivering this year," Ahuja said. "For anybody to wait to move forward until
standards are completed is not a good decision."
As Bellcore, Telcordia had announced contracts for supply
of what it calls "Next Generation Network" technology to Sprint Corp. for its
ION (Interactive On-Demand) initiative and to Canadian MSO Le Groupe Vidéotron Itée for
deployment of IP (Internet-protocol) telephony starting later this year.
Telcordia officials heavily stressed this side of the
company's agenda as it moves ahead under its new ownership.
"Cable is a very important part of our market
now," Ahuja said. Out of the approximately $1.2 billion that Bellcore registered in
revenues last year, more than $500 million came from outside of its traditional regional
Bell operating company base, he noted.
"This whole transition [from switched circuit to IP]
is going faster than we thought it would," added Telcordia CEO Richard Smith.
"It's going to come sooner than later."
Telcordia's message is that by June, it will have the
IP-based platform available to support provisioning of first-line-quality services over
cable and other types of networks.
This will include the means of setting up and managing
calls and provisioning the one-dozen or so most popular features of the
intelligent-networking capabilities of switched systems.
But where a few months ago, it looked as though the
architecture that Telcordia's system is based on would be the one of choice in the
specifications being devised by the PacketCable task force, the matter is far less certain
today.
"We expect that there will be evolution of the
technology, and we will continue to support these innovations as industry standards
evolve," Ahuja said.
Noting that there are "more object-based [software]
standards being talked about, like DOSA [Distributed Open Signaling Architecture],"
Ahuja added, "We are absolutely committed to supporting those as they get more mature
over time."
But for AT&T Corp., the driving force behind the DOSA
architecture, the goal isn't to evolve to this platform, but rather to launch on it
as the company transitions from switched-circuit telephony over cable to IP.
"You might see some field trials based on [the
alternative architecture supported by Telcordia], but AT&T wants to go commercial on a
platform that scales to its requirements and that fits in with the legacy network that it
already has in place, which is what DOSA is all about," said a vendor official
working with the carrier, who asked not to be named.
The Telcordia architecture makes use of a protocol known as
Multimedia Gateway Control Protocol. MGCP uses a simple set of "primitives," or
basic instructions, to allow an IP-telephony network or large segments of it to function
as a "virtual switch."
A centralized "call agent," or controller,
interacts with distributed end-user gateways as if they were line cards interfacing with
the external networking environment.
MGCP supports the "dialogue" between the call
agent and the gateways, allowing IP calls to be originated from simple, relatively
unintelligent pulse code-to-IP signal translators attached to standard touch-tone
telephones.
But it is not designed to exploit the richer functionality
environment that comes with a distributed architecture that employs more intelligent
end-user devices, noted Jeff Orwick, field-systems engineer for NetSpeak Corp.
Orwick is one of the brains behind SGCP (Simple Gateway
Control Protocol), which is the basis, along with IDCP (Independent Device Control
Protocol), for MGCP.
In contrast, as described by Chuck Kalmanek, division
manager at AT&T Labs and a member of the DOSA team, DOSA ties together three key
points within the HFC (hybrid fiber-coaxial) voice-over-IP cloud:
The end-user BTI (broadband-telephony-interface
device), which connects standard telephones, as well as Web phones, to the network;
The CMTS (cable-modem-termination system), which
controls distribution of data signals over the HFC plant from the headend; and
The gateway controller, or call agent, which
interfaces with both the BTI and the CMTS.
In its simplest articulation, the system operates via an
initial request for call authorization from the BTI to the controller, which sends the
authorization to the CMTS based on policies established using the industry standard COPS
(Common Open Policy Services) protocol.
By using the gateway controller both to authorize calls and
to convey policy, the architecture is "going in the same direction where things like
VPNs [virtual private networks] are going, where the authorization of resources is being
pushed to the edge routers," Kalmanek said.
Thus, a wide range of resources can be added to the
authorization process, depending on the types of services that the end-user is paying for
and equipped to receive.
At the same time, the system uses the Resource Management
Protocol as the means of communicating between the BTI and the CMTS, assuring that the
right amount of bandwidth is allocated in the downstream and upstream directions for the
particular application, Kalmanek added.
To enhance the instruction-transmitting capabilities of
this architecture, AT&T and other entities, including MCI WorldCom, are looking at an
alternative -- or, at least, a supplement -- to MCGP, now referred to as
"SIP-Plus." This is based on additions of IN-function instructions to the
Session Initiation Protocol.
SIP-Plus goes in the same architectural direction
envisioned by DOSA, where intelligence, in the form of client servers, is distributed
throughout the network with the flexibility to operate at very simple levels on very thin
clients or to perform highly complex tasks on personal computers and other high-level
processors.
"Our goal is to balance all of the resources within
the broadband network so that we can provision the fullest range of services with maximum
efficiency, and SIP appears to be an important piece of that," Kalmanek said.
Orwick said discussions are under way with Henning
Schulzrinne -- the Columbia University researcher who is the widely acknowledged
mastermind behind SIP -- to add the enhancements.
"It's pretty straightforward, and he seems
receptive," Orwick said.
The first iteration of the Telcordia system will rely on
creating the IN functions from within, but it will be enhanced during the second half of
the year to import SS7 (signaling system 7) functionality from outside resources, Ahuja
said.
However, he added, "Our customers are not relying on a
class-5 switch to be there."
The differing agendas, architectural solutions and
timelines for deployment pose new challenges to the PacketCable task force, noted Raja
Natarajan, director of product marketing for voice-over-IP at Motorola Inc.'s
Internet-networking group.
"The main concern is scalability," he said.
"In a network-centric approach, you need a really big machine to keep track of every
call, and eventually, that can be a hindrance to scalability."
