SELSC has extensive experience with H.323 video conferencing and has determined which deployment techniques provide the most reliability. As a result, SELSC has established “Best Practices” for H.323 video conferencing.

This document describes the basic network design and Quality of Service (QoS) issues for H.323 and explains the results from testing various video systems.

This document also includes recommendations on the type of equipment and technology that best meets essential quality standards required for its video conferencing service. These recommendations are based on exhaustive test results and “lessons learned.”

If you have questions regarding these technology recommendations, please contact SELSC.

Register

Please contact the SELSC Support Center in order to register your video conference unit… Information required on the form includes:

• On-site Videoconferencing Specialist contact for the videoconference. (Must have videoconferencing expertise and be available during the conference)

• Type of equipment being used.

• IP addresses for the conference.

• Description of network.

• Register your information with SELSC well before your first event.

• Notify SELSC of changes in information (especially equipment and IP address changes.)

Important Note: Password on codec’s should be easy accessible. Please register your videoconferencing capabilities with us even if you do not have specific events scheduled. We can help you prepare for future events if we have information on file about your equipment, network, and videoconferencing needs.

Schedule

Once you have registered your information with SELSC and prepared for the optimal videoconference, it’s time to schedule your event. Only certified videoconferencing specialists may schedule videoconferences with SELSC.

  • All videoconferences must be scheduled with the SELSC support center.
  • Email cedric.banks@la.gov or call 1.225.342.4253
  • Website to schedule a videoconference http://76.165.208.7
  • One-time events must be scheduled with two (2) days prior notice.
  • Resources may not be available without adequate notice.
  • Classes/multi-day events must be scheduled 15-24 days in advance.
  • Resources may not be available without adequate notice.
  • Important Note: Please follow SELSC’s Videoconferencing Service Guidelines to
  • Ensure availability of services when you need them.

Set-up Time Test

The importance of testing cannot be stressed enough. Testing with the SELSC Support Center prior to the event will help ensure a successful videoconference for everyone Involved. Here are some general testing guidelines that will minimize the potential for

  • All conference will connect (30) thirty minutes before each session start.
  • Test the equipment to be used in the actual location of the videoconference.
  • Test everything with the exact configuration as it will be used for the conference.
  • Testing with other equipment in the same location is not a real test.
  • Make sure to test all changes made to the system/network prior to the event.
  • One-time events must be tested at least one (1) day before the event.
  • SELSC can help you test as soon as we know about the event.
  • Classes/multi-day events must be tested one (1) day before the first in the series

Certify

The Videoconferencing Room

Your rooms should be certifying so that you can support the services of the SELSC. Each institution has several room units on a campus; need to have each room certify with the MCU. If your institution has a MCU or other device that controls or schedule videoconferencing rooms on the campus. The institution can only certify the MCU.

Rooms will be asking to the following to pass a room certify.

  • MCU will dial out to rooms and connect.
  • Must pass teacher and student video / audio.
  • Must be able to pass Document Camera.
  • Must be able to pass PowerPoint

Maintenance

SELSC suggest that all endpoint have maintenance and next business day parts coverage provide by the installing vendor or vendor sponsored program.

Basic Network and QoS Issues for H.323

SELSC has determined that the best way to manage bandwidth contention is to connect the video equipment to a dedicated Ethernet segment on the router. A variation on this option is to have switches that support – and are properly configured for – the 802.1P protocol connected to a separate Ethernet port on the router. This protocol marks video traffic as priority.

Testing has confirmed the importance of using a full duplex Ethernet connection. Even just one 384Kbps call on a 10Mbps half duplex connection produced visible video artifacts – albeit minor – in test connections. In addition, we observed that even when devices were capable of full duplex, they couldn’t auto negotiate correctly, resulting in mismatched duplexes and failed video conferences. We found the only way to get reliable quality is with equipment capable of setting the speed and duplex features manually.

As of January 2006, there is an open issue when connecting a 3550 to a 2950 and using hard coding. Contact SELSC if you have this sort of connection.

System vendors now offer High Definition (HD) video systems. These systems do provide a better picture (assuming the monitor can display them) than non-HD systems at 384Kbps. Bandwidth rates of 1Mbps or greater are required to take advantage of these improvements. SELSC video conferences are normally at either 384Kbps or 768Kbps, although other speeds can be arranged. As systems with greater capabilities are installed, SELSC will scale the network as required.

H.323 Devices

Systems

Systems – also referred to as “end points” – provide for real-time, two-way communications. Typically, H.323 systems are either computers running H.323-compliant software with specialized hardware, or group conferencing systems using H.323 systems. PC-based individual H.323 systems are not well suited for production conferencing and are not considered in this document.

Customers considering implementing H.323 video sites should consider the various choices of H.323 systems. There are a number of native systems to choose from today.

Polycom, Tandberg, video systems underwent extensive testing and were individually evaluated for their reliability and quality.

In addition, SELSC tested a number of systems from other vendors for interoperability with each other and for performance on the network. Here is a recap of the test results for the systems listed above. The last section of this document contains SELSC’s recommendations.

Polycom VSX, HDX Series

These units can be manually set for 100Mbps full duplex, which provides good quality at 384Kbps. 384Kbps is SELSC’s recommended speed for systems. Both models provide simple setup and ease of operation. The Polycom systems have a built-in web control interface. This interface can be set to require a password to gain access to critical setup areas (and SELSC recommends that you both add a password and tell SELSC what the password is). The default password is the last 6 digits of the serial number as shown on the bar code sticker.

The EX/FX/SP/VSX Polycom models are geared toward addressing the set-top market, but only the EX/FX and VSX models can be enhanced with second monitors and dual channel motion (not H.329), where the graphics and participants are “live”. SP software version 7.2 and above and FX/VS version 4.2, 5.1 and 6.1 have been certified.

Polycom also has 3 VSX models which need to be at least at version 7. As of August 2004, the VSX models have some known issues running at speeds greater then 512Kbps. Since our standard rate is 384Kbps, we feel that these units are acceptable and have been assured by Polycom that this rate related shortcomings are being addressed. Some Polycom models offer a Telnet-based Open Captions (manually entered) option when connected to other VSX units or to P-TEL 970 models at versions above 6.1. All Tandberg systems have Telnet-based Open Captions. Cross platform compatibility is on a trial and error basis.

This unit performed quite well, but installation and initial setup was a bit more difficult than the Polycom. It is a better fit for a classroom situation than the Polycom FX or SP. It performs best as a dual monitor system where one of the monitors is a 29 inch or larger VGA display. It has a web control interface that can be turned on and off. The P-TEL has two levels of web access: one is for users, the other for administrative functions. The web interface requires password protection before it will allow access.

Be aware that this is a PC platform solution running Microsoft Windows 2000 and is susceptible to Microsoft vulnerabilities. If using this model, be sure to keep it up to date by installing Microsoft patches and security fixes available at http:///windowsupdate.microsoft.com. This site should be checked at least once a month or set to auto-update.

Tandberg 880/1000/2500/6000 and Some MXP Models

All of these units performed well and have a dual stream mode (except the model 1000), allowing full-motion graphics and video at the same time. When using the dual motion mode, both motion channels are something less than the connected rate. Tandberg 2500 and 6000s are aimed more at the telemedicine or distance learning markets. The 6000s are the most feature-rich and can be equipped with many options to enhance video conferences.

The 880 model is a set-top model with features and functionality comparable to the Polycom FX.

The 1000 model is a set-top unit not designed for group conferencing, but is more aimed and the executive desktop market.

The Tandberg units come equipped with a web interface. By default, the interface has no password set but can be invoked via the password command via Telnet. Users connecting with the web interface have full access to the system including all administrative functions. When first enabled, the default password is TANDBERG. We strongly suggest setting a password and informing SELSC of the password.

All Tandberg models listed above work well when running version E1.2/B6.3, E2.2/B7.2, E3.0/B7.3, E3.4/B8.4, E4.0/B9.0, or E5.0/B10.0 for regular units and F3.0 for their MXP platforms. Versions 4.1, 5.3, and E2.3 exhibited some interoperability issues and should be avoided. Tandberg publishes a compatible hardware/software compatibility grid in the release notes of all their current software. As of September 2005, all Tandberg units should be at E4.2 (or the BX.x equivalent) or above for best results.

MCUs

A Multipoint Control Unit (MCU) is a bridging or switching device used in support of multipoint video conferencing. One part of the MCU handles negotiation between all terminals to determine common capabilities. Another part does the mixing, switching, and other processing for audio, video, and/or data bits. SELSC provides MCU facilities as needed for multipoint conferences and recommends that customers avoid purchasing or installing their own MCU facilities.

Gateways

SELSC does not provide gateway services for connectivity and recommends that customers avoid purchasing or installing their own gateways.

Technology Recommendations

From the experience gained during this project, SELSC has developed the following technology recommendations. These recommendations are to assist customers with the implementation of a video site. The recommendations cover issues related to LANs, WANs, Firewalls, and system devices.

LAN

  • The LAN should be able to support 100Mbps, full duplex, hard coded, Ethernet connections between the system and router interface. Copper wiring should be at least level 5 and not longer than 300 feet. Longer runs should use fiber media converters. These converters should support the manual settings of speed and duplex (to 100Mbps, full duplex).
  • Sufficient QoS bandwidth needs to be available to support the number of simultaneous video conferences the customer requires.

Note: This recommendation applies to both the LAN and the WAN side.

  • When determining the amount of bandwidth, overhead (205) must be included in the equation. [For example: allow 500Kbps of bandwidth for a 384Kbps connection)
  • Network devices must allow manual setup for speed and duplex to ensure that Ethernet speeds and duplexes match. Auto-negotiate set in systems, switches or routers will cause problems.
  • Each system should have a dedicated 10/100/1000 switched (full duplex) Ethernet segment for H.323 or a dedicated VLAN with QoS configured, to a dedicated 100 or 1000Mbps Ethernet port on the router.
  • Each video site must be certified with SELSC before it is available for use on the network.
  • Any changes to video sites should be reported to SELSC to be recertified to ensure continued quality video conferencing services.
  • The IP addresses used must be native and not translated through NAT.

Firewalls/Access Lists

  • The firewall should have built-in filters that handle H.323 and should not adversely affect the performance of the H.323 data stream.
  • The firewall should permit SELSC to access port 80 on the video system to support remote management.
  • The firewall appliance must be fast enough to support the required data stream without dropping packets and should operate with less  than 50ms delay.

As of January 2006, SELSC has two customers with video deployed behind a firewall. There are special setup considerations that need to be taken into account when passing video through a firewall. So far, Cisco PIX and Sidewinder firewalls work well enough to allow the systems to get certified. Tandberg and Polycom both offer firewall traversal products which have yet to be deployed or tested by SELSC.

WAN

  • The connection to SELSC’s network must be on an SELSC-managed network device and the system placed in SELSC’s video VPN.
  • Load-balancing traffic in routers is not recommended with H.323 IP packets due to potential problems with delay when packets are reassembled.

Recommended Systems:

  • Polycom SP with software version 7.2 or above.
  • Polycom EX/FX/VSX or VS4000 with software version 4.2 or above.
  • Polycom VSX with 7.x and some 8.x revisions. Some combinations of revision 8 and VSX hardware have some issues. All issues of this type to date do have some sort of acceptable work around.
  • PictureTel 900 series (950/970) software versions 6 (preferred) 5, or 4. Note that this series is obsolete and has reached end of life and support.
  • Tandberg 800, 1000, 6000 or 2500 with software versions E1.2/B6.3, E2.2/B7.2, E3.0/B7.3, E3.4/B8.4, B10.0 or F3.0. Due to problems experienced, do not use E2.3 or B5.x software loads. Newer Tandberg models host an MXP designation and have no serious issues which would prevent point-to-point calls.