October 1999

H.323 Video Conferencing
THE INTRICACIES UNRAVELED

BY PEG LANDRY

When the H.323 protocol was introduced in 1996, it was seen as a consumer luxury promising to unify voice, video, and data across a single network. Today, H.323 is still considered an infant protocol, and has had to prove itself when compared to "old reliable," H.320. Despite myths of lower Quality of Service (QoS) and bandwidth limitations, H.323's flexibility and scalability has spurred the growth of real-time multimedia applications over IP networks. Developments such as continuous presence and streaming media are enhancing business applications like corporate training and executive board meetings, inciting new and innovative uses of H.323 technology.

Since the technology first became available in 1990, Fortune 500 companies started investing large sums of money in dedicated H.320 video conferencing systems and the networks to support them. The expense of these costly systems was justified by reduced travel costs, shortened decision making cycles, and increased productivity (due to less time spent away from the office).

Company executives recognized the value of meeting face-to-face with key customers, suppliers, and employees, but wanted something less expensive. The desire for cost savings and the demand for more broad-based implementation of real-time, two-way multimedia communications created the need for these companies to migrate from their ISDN transports to Internet Protocol (IP).

H.323 provides the essential interoperability between communication endpoints and promotes scalability, convenience, and productivity; high cost, diminished network capacity, and lower QoS become misconceptions. Transitioning to H.323 protects the investment in a legacy conference system as it's leveraged onto an existing corporate infrastructure.

Planning For H.323 Deployment
The requirements that real-time multimedia conferencing place on a network are not much different than that of traditional IP traffic. Network administrators should evaluate and plan before deploying this new communications medium. There are several important considerations:

Evaluate Current Network Capacity. How much bandwidth is currently being consumed on your existing local or wide area network (LAN/WAN)? With many network diagnostic tools available, administrators can evaluate current usage on all segments of your network and identify any potential bottlenecks.

Characterize The Type And Frequency Of H.323 Conferencing. Once you determine how much bandwidth you expect conferencing to consume, calculate how many clients can be safely deployed and determine if network upgrades are necessary to accommodate increased traffic.

Define User-Specific Needs. Do you plan to use conferencing for small two-way point-to-point sales meetings, or will it be used for CEO’s quarterly communication to employees at multiple sites around the world? Conference variables used to determine bandwidth consumption include the kind of media (audio, video, or data) that will be used in conferences; the types of codecs (compression/decompression algorithms) used by client endpoints; and parameters such as video resolution, frame, rate and sound quality.

Review Firewall Design. Does your existing firewall device have enough bandwidth for H.323 multimedia traffic? An H.323 call is made up of numerous simultaneous connections, so multimedia traffic can have greater continuous bandwidth than data traffic. It is essential to guarantee that your firewall has the network capacity to transmit H.323 traffic. Consult your firewall documentation or contact your vendor to find out whether your firewall supports this traffic.

Implement QoS Measures. You can control QoS on your LAN/WAN by properly engineering your IP network. Deploying gatekeepers is key to maintaining QoS for H.323 conferencing. Gatekeepers promote admissions control, bandwidth control, and zone management. Linking distributed Multipoint Control Units (MCUs) can optimize the use of resources on your network. QoS is also enhanced through the implementation of IP multicast, which is an extension to the IP networking standard, addressing the need to handle group communications. MCUs can use multicast to efficiently distribute data streams to multiple conference participants over an IP network.

With your network optimized for H.323 conferencing, you are now ready to deploy it within your organization. There are many aspects to a properly configured H.323 network. The following phases outline the steps you should take in deploying H.323 on your network. Take time to test performance on your network as you complete each phase. This will help you identify and isolate any problem areas.

PHASE 1:
Pilot Test On A Dedicated LAN

• Install client endpoints and test in a point-to-point conference to make sure clients are properly configured and can establish an H.323 connection. Ensure that clients are set with proper audio and video codecs and performance is acceptable.
• Install and start the MCU and the gatekeeper that will control multipoint conferencing on your network. Do this on the same subnet where you installed the H.323 clients. Allocate bandwidth as determined in your pre-deployment planning stages.
• Conduct a small multipoint conference on your MCU. Connect three endpoints through the gatekeeper to start. Use network monitoring devices to determine how much actual bandwidth is being consumed.
• Continue to add client endpoints to the multipoint conference one at a time. Check performance and bandwidth use as you add each client.

PHASE 2:
Extend To LAN/WAN

• Install client endpoints at remote locations on your WAN. Connect these clients over your WAN to your MCU. Check performance and bandwidth use with each client you add.
• To optimize bandwidth over your WAN and distribute the bandwidth load, install an MCU in each remote location. Connect client endpoints to their local MCU and link MCUs across WAN links.

PHASE 3:
Secure H.323 Internet Conferencing

• If your organization has a firewall, configure it to accept H.323 traffic.
• Allow H.323 client endpoints to connect to multipoint conferences controlled by a gatekeeper and MCU on your corporate network, traversing your firewall if applicable.

PHASE 4:
Incorporate H.320 Endpoints Via Gateways

• Set up an H.323 to H.320 gateway device on your network. Gateways bridge packet-based and circuit-switched networks enabling H.323 endpoints to communicate with H.320 endpoints.
• Allow H.320 client endpoints to connect through the gateway to multipoint H.323 conferences controlled by a gatekeeper and MCU on your corporate network.

TROUBLESHOOTING
Audio/video communication requires low latency between sender and receiver in order to maintain quality because audio and video data lose relevancy to the receiver if not delivered in a timely manner. Troubleshooting multimedia networks involves a good deal of trial and error, and some of the potential problems that could arise include bandwidth shortage, network latency, and client/MCU limitations.

Moving Forward
Network administrators can be comforted by the fact that they won’t have to waste money getting rid of their old ISDN-based H.320 systems and starting from scratch. With the recent developments in video conferencing technology, the time to transition is now in order to reap the full benefits of the technology and be better equipped for what’s to come.

As video conferencing continues to permeate the business market, more and more companies will be attracted to the ease and flexibility the IP network infrastructure offers them. With people relying more and more on the Internet for conducting business, companies still need to recognize the importance of face-to-face interaction. H.323 desktop conferencing offers the best of both worlds: virtual communication between multiple parties without spending the time, money, or aggravation of always having to leave the office.

Through up front evaluation and planning, corporations today are successfully integrating H.323 conferencing into their existing networks providing a valuable new method of communication to their employees, partners, and customer base.

Peg Landry is Director of Marketing, for White Pine Software. For more information, please visit their Web site at www.wpine.com.

BY STACY SAXON

Video conferencing is becoming valued as a business-critical application. Lower equipment costs, increased market pressures, and increasingly dispersed work groups having been driving up video usage rates at an annual rate of over 30 percent. As video conferencing products become more affordable, systems can be widely deployed throughout organizations. In Fortune 500 organizations, and government and education markets, customers are evaluating Internet Protocol (IP) and the Local Area Network (LAN) as the preferred transport for video conferencing.

As an alternative to conferencing over a circuit-switched network (such as ISDN), IP conferencing offers a number of benefits, including lower cost and improved network utilization. Video over IP delivers a cost-effective conferencing solution by leveraging existing networks and infrastructure.

Moving Toward H.323
As with any new standard, there are difficulties when implementing video over IP as a reliable, robust solution. Moving video from the circuit-switched (H.320) world to IP means losing Quality of Service (QoS), as video over IP requires working with a less mature standard (H.323) that is not yet as feature rich as the H.320 standard.

IP-based video conferencing systems have been available from a number of vendors over the past two years — some hybrid IP/circuit-switched systems and some IP-only systems. The majority of IP-only video conferencing systems are now pilot implementations residing on parallel networks, as customers aim to understand the impact of video on the LAN. The hybrid IP/circuit-switched video conferencing systems provide the reliability of circuit-switched networks while moving toward IP implementation.

Some customers are beginning their IP-conferencing network deployments with voice over IP (VoIP), which addresses a few of the video over IP issues, such as latency. This will facilitate the successful deployment of video over IP, although the increased bandwidth requirements and feature robustness for video over IP must still be resolved.

Interoperability is yet another consideration. The current IP conferencing standard, H.323, is still immature — about at the level where circuit-switched/H.320 video conferencing was six years ago. Given the infancy of the standard, interoperability among endpoints, as well as with network devices, including gateway to gateway interoperability, is not guaranteed. However, the standard is maturing very quickly.

The Future Of IP Conferencing
As the H.323 standard evolves, we will see greater interoperability and enhanced features supported in a H.323 environment. This will enable a significant movement toward establishing a level of QoS that is required by customers. In addition to H.323, other standards, including MGCP and SIP, are evolving to support video over IP. Industry organizations such as the IMTC are working toward promoting standardization of IP conferencing protocols. It remains to be seen if any one protocol will become the de facto standard for video over IP. In the end, IP conferencing may exist as a multi-protocol environment.

Endpoint and network device vendors must work together with service providers and carriers to identify and provide solutions to customers for IP-conferencing networks — solutions that address QoS and interoperability, as well as enhanced feature support.

The majority of the market is not expected to fully migrate to IP-based video conferencing until the year 2002. Meanwhile, customers will continue to conduct pilot implementations, and move into early, small-scale deployments. Enterprise-wide deployment will not occur until QoS and interoperability issues are resolved. Customers who are not currently in pilot stages with IP video conferencing are, at a minimum, architecting and augmenting their network to support video conferencing. As the number of IP-capable video conferencing systems is expected to double over the next year, there will be greater movement towards full-scale deployment of video over IP.

As networks are developed to support IP conferencing, more and more applications will migrate to IP, which will become the primary means of conferencing for the converged voice, video, and data network.

Stacy Saxon is Director of Product Marketing, Video Conferencing Division for Polycom. For more information, please visit their Web site at www.polycom.com.