|The Emerging Role Of The Gatekeeper
The driving force behind the IP revolution is the ability to use packet networks like the Internet for real-time voice and video communications. The International Telecommunications Union�s H.323 specification provides the technical framework for supporting voice and video over IP. The specification defines a �gatekeeper� as an optional network component for call control, managing network resources, and setting policies for how the network can be used (and by whom). As large-scale converged networks are deployed for IP telephony and multimedia conferencing, gatekeepers are transcending their original definition.
- Have emerged as the IP networks central intelligence agent and control
center for converged voice/video/data networks;
- Provide a portal for integrating multiple protocols needed for achieving true end-to-end
interoperability in a hybrid network that links the existing PSTN with the IP world;
- Provide the underlying technology needed for implementing soft-switch PBX
- Provide the vehicle for delivering compelling new IP services and applications.
All gatekeeper implementations use the same building blocks, but IP
telephony deployments in enterprise and carrier/ISP environments face different challenges
and thus call for different gatekeepers. Indeed gatekeeper-enabled
capabilities are emerging as competitive differentiators among the product and service
offerings of key players in the rapidly growing IP telephony market.
THE ENTERPRISE MARKET
The enterprise market is concerned, first and foremost, with workforce productivity. Hand
in hand with this demand for productivity increase is a need to measure sustained hardware
and services return on investment (ROI). Upgrading a corporate intranet to support
IP-centric, real-time multimedia communications capabilities positions an enterprise to be
able to reap the benefits of enhanced productivity as well as increased revenues resulting
from more efficient and effective collaboration among workers, with customers, and with
supply-chain vendors. Additional benefits of a converged voice/video/data network include
cost savings for IP telephony toll-bypass applications, and simplified network management.
Gatekeeper-Enabled Network Management
Enterprise gatekeepers enable IT managers to implement new converged voice/video/data
services using existing corporate IP networks without compromising existing mission
critical services. Gatekeeper-enabled network management tools provide IT managers
powerful, yet easy-to-use controls for defining how voice and video traffic is managed
over IP networks just how much bandwidth may be used for a given call, and what
type of calls get priority. Through the gatekeeper, network managers can configure,
monitor, and manage the activity of registered network users. They can define who can make
calls along with what kinds of calls can be made. Network administrators can also access
online event logs to monitor network activity and adjust policies to optimize network
Other unique next-generation gatekeeper capabilities offered by vendors include a
database of neighbor gatekeepers for optimizing and controlling
inter-gatekeeper communications. The database also contains network topology information.
This information allows network managers to divide the network into components and use
topology island information for efficient subnet routing, enabling least cost routing
schemes and load balancing across gateways.
The New Softswitch Enterprise PBX
Next generation enterprise gatekeepers provide their greatest benefit in the form
of a compelling softswitch alternative to traditional proprietary PBX
capabilities such as voice mail, paging, and call waiting. However, gatekeeper-enabled
enterprise networks go well beyond simply matching typical PBX capabilities. Converged
networks inherently provide a platform for easier implementation of complex services
requiring tight integration between voice and data such as follow-me call
routing and unified messaging. Because gatekeeper logic in new IP-centric
softswitch architectures is separate from the switching logic of H.323
gateways, the gatekeeper acts as the programming platform to easily implement new
services. Ease of service definition and management through the gatekeeper is in turn
dependent on the power and depth of API implementations offered by different gatekeeper
Field service cost savings are also inherently provided through the gatekeepers
ability to automatically register end points (e.g., phones) as personnel move from one
location to another whether it is across the hall or to a separate geographic
location miles away, eliminating moves, add, and changes (MAC) service
THE CARRIER MARKET
Whereas the adoption of IP communications in the enterprise is being driven by
enhanced productivity and cost savings associated with more efficient network management,
increased revenue generation is the business reason for carrier and service provider
deployment of IP telephony. To heighten competitive advantage in the increasingly
competitive global telecommunications marketplace, service providers are designing
converged networks capable of supporting new IP services that in turn will generate new
revenue streams. In addition to being the vehicle for implementing next-generation IP
services, the gatekeeper is also the component that can bridge the existing
PSTN with IP networks a critical need for end-to-end interoperability across a
global telecommunications network.
Public expectations for high-quality, low-cost transport, next-generation networks require
carrier-class gatekeepers to transport calls in the most cost-effective way to enhance
revenues. Meeting these demands requires high performance, scalable, carrier-class
Service-class networks must be high performance, moving the greatest number of calls
or service requests in the most efficient and reliable manner. Performance
is important in large enterprises but it is critical to the service providers core
revenue-generation business model. As enterprise-class gatekeepers emerge with access to a
host of services that enhance workforce productivity, carriers will use their
gatekeeper-driven networks to manage and transport vast amounts of network traffic based
on these new IP services. Guaranteed transport will become a primary revenue stream, based
on a coupling of least-cost routing mechanisms, high call volume performance, and tie-ins
to third-party billing systems. Distributed H.323 and new decomposed gateway architectures
using centralized media gateway controllers (such as MGCP architectures) will provide this
performance without sacrificing quality of service or compromising service levels.
Gatekeeper-enabled global carrier networks must be able to scale exponentially, well
beyond the scope of enterprise-class gatekeepers that are typically equipped with only a
limited number of end points (hundreds). Offering any particular service on demand to one
or thousands of end points requires rapid setup and teardown scalability, only
achievable on telecom-grade hardware built to five-nines reliability, coupled with equally
reliable, robust gatekeeper software. In carrier environments, one of the primary
competitive advantages of deploying gatekeeper-enabled IP telephony networks is the
elimination of the need for centralized provisioning entities. Unlike switched networks,
clients and servers can be individually added to gatekeeper-enabled converged networks
without mandating centralized provisioning.
Besides the obvious need for high performance and scalability, other carrier-class
gatekeeper requirements include:
- Policies: Gatekeeper-enabled architectures provide effective management
of underutilized bandwidth through a robust set of predefined or customized policies.
These policies provide for tighter bandwidth management, least-cost routing, and detailed
call activity logging. Customized policies guarantee fulfillment of service level
agreements structured on new criteria such as total number of simultaneous calls in a set
bandwidth, or total bandwidth consumption in a specified time increment versus the current
cents per minute scenario in circuit-switched environments.
- Systems Interface Support: Connections to LDAP, RADIUS, and DIAMETER
for directory services and other critical authorization, authentication, and accounting
information needed for call detail records and billing/rebilling.
- Interoperability: Ties into other telephony protocols including the SS7
signaling protocol used in the PSTN, and new emerging IP telephony protocols such as MGCP
for decomposed IP gateways, as well as other communication interfaces for vendor-to-vendor
inter-gatekeeper communication for dial-around capabilities for accessing
multiple service providers.
- Distributed architecture: Based on a modular, flexible, distributed
design ideal for large service providers seeking to escape more rigid, tiered
switching and network architectures that have forced CLECs and other alternative carriers
to rely on co-location at competitors POPs.
- Robust API: APIs allow carriers/service providers to integrate
gatekeeper operations with customized IP services logic and external databases. The APIs
further facilitate formation of a SUPER gatekeeper composed of multiple GK
components. This feature is critical in design of scalable and reliable networks. Support
for third-party plug-in modules enables carriers and service providers to
quickly introduce new gatekeeper-enabled value-added applications.
- Network management tools: Tools for rapid and accurate assessment of
all call activity and network load are critical for maintaining network performance and
efficient call routing based on available network resources.
For carriers and next-generation IP telephony service providers, the gatekeeper
provides the essential building block needed for gatekeeper-enabled IP service creation.
Gatekeeper-enabled service creation environments are built around carrier-class platforms
that provide high performance and fault tolerance. These open service creation
platforms are key to creating new revenue-generating IP services such as Internet call
waiting, calling card services, one-number services, follow-me/find-me services, modem/fax
emulation, etc. (Table 1.)These platforms are aimed at speeding service
providers ability to offer value-added services for converged networks that span
across PSTN and IP data networks.
||Voice + Web Call Centers
||Voice + Web + Transaction Call Centers
||Voice + Video + Transaction Centers
||Internet Call Waiting
||Follow-Me/Find-Me Voice Services
||Intelligent Appliance Calling Interfaces
||Self-Serve (HTML-based) Multipoint Audio,
Data And Video Conferencing Calling
||Self-Serve Community And Content Services
||Voice-Activated Services Menu
||Internet Voice Messaging
||Internet Voice To E-mail,
E-mail To Voice
Fax To Voice
|All Earlier Services, Plus Personal Video
It has been just three years since the intellectual property embodied in the ITU H.323
specification became commercially available in the form of the H.323 protocol, and
gatekeeper-enabling technology from companies. Since that time, the IP communications
revolution has taken hold, and real-time voice and video communication over converged
networks is being deployed globally in enterprise and carrier environments. Today, there
are hundreds of thousands of people around the world using gatekeeper-enabled IP telephony
products and services. As the number of IP-connected devices and people grows and reaches
critical mass, IP-centric communications will be commonplace and the gatekeeper will
continue to play an increasingly important role as the heart of a host of
compelling new applications and services for converged networks.
Michelle Blank is Vice President of Global Marketing, RADVision, Ltd. RADVision
provides core technology components for building complete H.323 multimedia networking
solutions. For more information, visit their Web site at www.radvision.com