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Videoconferencing General Information
|Supported Video Collaboration Tools|
|Tool||For More Information|
|Telepresence and H.323||kb.wisc.edu/telepresence|
UW Extension Instructional Communications Systems (ICS), located at the Pyle Center, has several audio and video conferencing services.
- H.323 Gatekeeper1 that is open to all in the UW System at no cost. Use of this gatekeeper is necessary to use the Global Dialing Scheme2.
- Contact ICS for Cisco Jabber Video software and licenses.
- ICS also offers Blackboard Collaborate, a software-based videoconferencing technology.
- ICS has a standard definition Polycom at 22.214.171.124 for test calls. This can be used to test your H.323 videoconference equipment.
1 A Gatekeeper lets you refer to a videoconference device with a number (an E164 number - like a telephone number). Gatekeepers came about as a way to let ISDN video codecs call IP video codecs. Another advantage of using a gatekeeper is that a codec can be moved to areas with different IP addresses while still keeping the same E164 number. Gatekeepers support easy calling between video devices registered to the gatekeeper.
Also, by restricting your video conference device to using a gatekeeper, the gatekeeper can be configured to block unwanted (spam) video calls.
Internet2 operates a Video Exchange.
Our goal is to facilitate high-quality communications technologies that leverage advanced networking. To this end, we operate a national video exchange to facilitate easy and cohesive telephone style dialing for advanced videoconferencing and telepresence. Our core signaling strategy is based upon ENUM and NRENum.net, with continuing support for the Global Dialing Scheme and SIP trunking. This combination of services in conjunction with advanced telepresence bridging and carrier peerings provides a core infrastructure that the broader research and education community can leverage to achieve unified dialing and reachability across diverse protocols, and across the world.
There are several ways to dial video conference calls:
- by IP address (126.96.36.199)
- by DNS Name (vcrp.doit.wisc.edu)
- by E164 number (16083164500)
- by GDS2 number (0016083164500)
- by URI3
- SIP 4
- by E164 number (16083164500)
- classic TelePresence rooms can ONLY dial E164 numbers
- by URI
2: The Global Dialing Scheme (GDS) is a specification developed by the now inactive Video Development group ViDe. It specifies how Gatekeepers can be linked together globally (similar to the Internet Domain Name System) to create an international numbering system for video conferencing equipment. GDS grew out of the H.323 world, and is not interoperable with classic Cisco TelePresence or SIP. GDS numbers in the US can be distinguished from SIP numbers because they include a leading 001 country code.
3: Uniform Resource Identifier (URI) is defined by an Internet RFC. As used in video collaboration, a URI consists of a left-hand side, an @ sign, and a right-hand side. The left-hand side can be a user name or an E164 style number, like a SIP or GDS number. The right-hand side can be a Domain Name like doit.wisc.edu or an IP address. The advantage of using a URI in video collaboration is that the user does not need to have the central network or video conferencing people explicitly configure a relationship with the server at the call destination - the URI contains the address of the Gatekeeper or Video Communications Server (VCS) that is needed for the call. The Internet2 Video community encourages the URI method of call dialing, because it usually has fewer local configuration dependancies than IP Addresses or the GDS.
4: Session Initiation Protocol (SIP) evolved as a way to support voice over IP and was adopted by the video collaboration community. Compared to H.323 dialing, SIP is easier to use behind a firewall because it uses a single TCP Port. Most modern video conference devices can be configured to use H.323, SIP and URI schemes.
H.323 videoconference devices can connect to one other device. To connect more than two endpoints, a Multipoint Control Unit (MCU) is used. ICS (see above) operates MCUs. Internet2 (see above) operates MCUs.
The H.323 protocol has some behaviors which are a challenge for firewalls and Network Address Translation (NAT). The protocol responds to call origination on different ports, and embeds IP addresses within packets. There are three ways to respond:
- Use a firewall that explicitly supports H.323 protocol, opening up the needed ports, and re-writing embedded IP addresses. The Cisco FWSM explicitly supports H.323 if the correct rule is used.
- Install a hardware device that manages H.323 devices inside a firewall.
- Put the H.323 device outside the firewall. (This is not a significant risk with hardware codecs, as these are special-purpose appliances, not general purpose computers. This is not a good alternative with software codecs.)
VideoLAN VLC is free, general-purpose, open-source software for encoding and decoding video. VideoLAN can send out the desktop as a video stream. Using this method, slide shows like Powerpoint can be shared with others.
The Videoconferencing Cookbook from the now inactive ViDe group.
Microsoft Research created ConferenceXP, a software-based videoconferencing technology. ConferenceXP is open source software. Much ConferenceXP development is happening at the University of Washington Center for Collaborative Technologies.
The WIDE project in Japan has developed DVTS (Digital Video (DV) over IP). There are standard definition and high definition versions of DVTS. DVTS requires high bandwidth - 20 Mbps.
Wainhouse Research analyzes the market trends, technologies/products, vendors, applications, and related services in the Unified Communications and rich media conferencing fields.
WebRTC is an open source real-time-communications effort. This could revolutionize video conferencing by building video conferencing tools into web browsers, similar to the HTML5 standard.Vendors of software, equipment and services
- Avaya (formerly Radvision) hardware and software, including Scopia Desktop
- Blue Jeans Cloud-based multi-point conferencing and Skype to H.323
- Cisco TelePresence (and former Tandberg) products; hardware and software H.323 codecs; immersive, room individual, iPhone/iPad
- CiscoJabberVideo5 a free, cloud-hosted version of Jabber Video (former Tandber Movi)
- Iocom commercial implementation of Access Grid
- Lifesize a division of Logitech
- Lync Unified Communications (presence, IM, audio, video), Microsoft product
- Polycom hardware and software H.323 codecs; immersive, room individual, iPhone/iPad/Android
- SeeVogh child of EVO, child of VRVS
- Skype known as a free audio and video client, paid options for multipoint use; Microsoft product
- Vidyo a videoconferencing system with hardware central equipment and soft clients. The Internet2 Commons has demo Vidyo services.
- VSee software video conferencing
A note about Skype: Skype is often considered for conferences with remote sites because people are familiar with Skype because they use it personally or because it is widely recognized as a free conferencing product. Skype uses peer-to-peer technology. That means that the Skype software on your computer may also relay other Skype calls to other locations for other users, and your video call may relay through other Skype users' computers. One impact of this is that this technology is non-deterministic - the path a Skype call takes will be different from one day to the next. In addition, if a user whose computer is being used to relay a Skype call ends their Skype program, the path for the in-progress Skype call will need to be re-provisioned. This may cause a drop in quality of a call in progress, or even cause a call to drop. Another impact of the peer-to-peer technology of Skype is that it potentially makes UW-owned computing resources available to non-UW users. Skype is also a proprietary protocol. That means that to bridge between Skype and H.323 requires a bridge that uses a method licensed by Skype. The only company that I know of at this time that provides such a bridge is Blue Jeans Networks (see above).
Another drawback of Skype is that its technology is proprietary - not standards-based. Skype is not interoperable with H.323. Blue Jeans offers transcoding between Skype and H.323, but Blue Jeans is a paid service. I am frequently asked to support video calls with Skype as the remote technology and a room-based Polycom or Cisco Tandberg endpoint here on campus. I don't know of a no-cost way to do that. But Cisco and Polycom do have free cross-platform video clients which are standards-based, and which do work on Cisco and Polycom endpoints here on campus. Campus departments can recommend that remote callers can use free Cisco or Polycom clients to make calls to our campus endpoints.
5: CiscoJabberVideo.com is way to get a free video conferencing client that runs on your computer and is hosted in Cisco's server cloud. This is a great way to hold job interviews for remote applicants. The process is to send the candidate an email with a link to CiscoJabberVideo.com, and another link to your video conference device. The candidate would go to CiscoJabberVideo.com, register for a free account, download and install the software, enter their username and password, and be ready to make calls. The candidate could click on the link to your video conference device in the email, and the call would be placed.
For example, I would use the link sip:firstname.lastname@example.org to call the Jabber Video on my desktop, or sip:email@example.com to call the Polycom in room 3139.
|Video Collaboration Resources at UW-Madison|
|creation in progress - to add rooms or suggest revisions, click on Comment link at the bottom of this article|
|Computer Sciences||3139A||DoIT||Polycom HDX||DoIT Departmental Use||CIO Program Assistants|
|Computer Sciences||2147||DoIT||Polycom VSX||DoIT Departmental Use||CIO Program Assistants|
|Rust/Schreiner||DoIT||Polycom HDX||DoIT Departmental Use||CIO Program Assistants|
|WIDMIR||WID||Cisco TelePresence CTS 3210||by appointment||see TelePresence at the University of Wisconsin-Madison|
|Education||L138||Education: MERIT||Cisco TelePresence CTS 3210||by appointment||see TelePresence at the University of Wisconsin-Madison|
|Health Sciences Learning Center||School of Medicine and Public Health|
|Van Hise||290||L&S: Learning Support Services||Cisco C40||L&S Departmental Use||David Macasaet|
|Bascom Hall||International Studies|
|Grainger Hall||School of Business|
|Biochemistry||Digital Media Center|
|Computer Sciences||Computer Sciences||Access Grid||by appointment||CS Access Grid Info|
|Pyle Center||several||Instructional Communications Systems||several||by appointment, fee||see Videoconferencing|