Vat works in two modes: point-to-point and multipoint. If the point-to-point (phone)
works, but multipoint (room conferencing) doesn't, a possible problem may be that your
network doesn't allow multicast traffic, or that no multicast route exists between your
client and the clients you are conferencing with.
For more information on Vat and IP multicast, visit the Introduction to MBone at Lawrence Berkeley National
Laboratory home page.
Vic uses multicast. A possible problem may be that your network doesn't allow multicast traffic, or that no multicast route exists between your client and the clients you are conferencing with. Contact your system or network administrator to resolve this problem.
If you only see your self, then your subnet doesn't have a multicast set up properly.
If you only see some of the users sending video, then the subnet of the users that you don't see probably doesn't have multicast setup properly.
For more information on Vic and IP multicast, visit the Introduction to MBone at Lawrence Berkeley National Laboratory home page.
If you are using a PCI based Sun workstation, please see the How can I use vic with a PCI Sun Video card?.
Vic will crash if you try to expand too many video thumbnails and you do not have enough shared memory. To fix this under SunOS or Solaris, edit /etc/system and add the following.
set shmsys:shminfo_shmmax=2097152
set shmsys:shminfo_shmseg=24
If you are running SunOS, rebuild the SunOS kernel to increase the memory size. Edit the kernel configuration file located in /sys/sun4m/conf with the line below and configure and install the new kernel. Note: If you have not previously rebuilt a SunOS kernel, it is recommended that you work with a system administrator who has this experience.
options SHMSIZE=2048
If the CVW client is running on a Solaris 2.6 SBUS platform, the audio and video tools will crash due to inability to access a graphics library in the expected location. To avoid the error, make a symbolic link from the expected location to the actual location of the graphics library.
cd /opt/SUNWits/Graphics-sw/xil/lib
mkdir pipelines
cd pipelines
ln -s /usr/openwin/lib/xil/devhandlers/xilIO_SUNWrtvc_ucode.a xilSUNWrtvc_ucode.a
Note, you should only perform this change on the Solaris 2.6 SBUS platforms; it is not required for PCI bus based systems.
Currently, the CVW system uses only the Vat and Vic tools for audio and video conferencing respectively. We are hoping that through the open source effort the CVW client's capabilities will be expanded.
To make use of the video conferencing capability available in CVW, the Sun workstation must be equipped with the Sun Multimedia Kit, which includes the SunVideo card and a camera. The list price is $1,895 and the part number is X488A. Note, the use of the multimedia kit requires the use of Solaris 2.x. More information can be found on our System Requirements page.
The CVW uses multicast for managing the multipoint audio and video conferences. Each room within the CVW has a unique multicast address, which the CVW uses to join and exit room-based video and audio conferences on the user's behalf. Multicast tunnels are used to connect systems on different subnets into the same multicast session.
Multicast networking is a technique used to send IP packets in a one to many fashion. IP multicast based routing is a network enabler for applications that require a “real time” communications capability over wide area IP networks. Multicast networking is commonly used on the Internet to provide a multipoint capability to network based audio and video conferencing tools. Multicast networks, or MBones, are considered to be virtual networks that share the same physical media as an organization’s network. MBone is a term used to refer to the multicast backbone on Internet, but the terms multicast network and MBone are often used interchangeably to describe an organization’s internal multicast network.
Computers on the network participate in a multicast session by prescribing to a multicast address. For example, to join in a multicast audio conference, all users would supply the multicast address to the audio software to join in the conference. This enables all audio conferencing participants to be talking on the same "channel". Multicast employs the class-D addressing scheme in IP, which ranges from 224.0.0.0 to 239.255.255.255. The address range of 224.2.*.* is the range used by the MBone users on the Internet for audio and video conferencing sessions.
For more information on multicasting, see the IP Multicast Initiative or the Introduction to MBone at Lawrence Berkeley National Laboratory.
For help installing IP multicast, see the CVW Multicast Installation Notes.
Multicast does not increase a system or network's vulnerability to system attacks. No system processes such as telnetd or rlogind will listen to multicast traffic, and there are no other system level (root uid) processes that are involved. Any risks are going to fall in the category of network snoop/spoof type attacks possibly resulting in denial of service. Please see IP Multicast and Firewalls for more information.
Basic information on multicast is available at the MBone initiative.
Audio conferencing can occur between two participants in a point-to-point fashion because the direct TCP/IP paths can be specified for each participant in a point-to-point conference. Multicast is required to support a varying number of participants in the group conference (greater than two), as in the room-enabled video/audio conferencing in the CVW.
The point-to-point audio conferencing within the CVW is useful to have a private, out of band, audio conference with another individual in the room (accessible by selecting the "Phone" menu option when right mouse clicking on the user's picture or name).
Unfortunately there is no multicast down/congestion indicator. How you will know if your tunnel is experiencing problems is from feedback from your users or periodic checks that you perform. Some symptoms of problems with your tunnel are:
The bandwidth used by the audio and video applications in CVW is controlled by the user. To get a feel for the kinds of bandwidth used, consider these scenarios:
To determine the overall network bandwidth consumed, multiply the above numbers by the number of users sending video or audio. For example, if there were 10 users sending 128 kbit/s video, 1280 kbit/s of bandwidth would be consumed. If one of the users invoked the audio tool, then the usage would jump to 1344 kbit/s (1280 kbit/s + 64 kbit/s).
The CVW Administrator can change the base multicast address, which is defined to be the first two octects of the multicast address. This can be done on the Network tab of the "System Settings..." menu item of the Admin menu.
This will happen if the base multicast address used by CVW is in use by another application. Change the base multicast address for CVW.
There are a couple more you could install (answerbook stuff and documentation), but you definitely need these packages. If you don't have these, or have an older version, Sun has some updated drivers you can download. Go to http://www.sun.com/desktop/products/Graphics/sunvideoplus.html and follow the Download link.
Next, some setup has to be done in order to make this work. These changes will probably be put into your startup script. Most of this information can be found in SunVideo Plus For PCI User's Guide. . This documentation can be found on Sun's product documentation website following the links to Sun Video Plus which is a Hardware Graphics Product.
First, you need to set two variables in your environment: XILHOME and O1KHOME (that's a letter O as the first character):
Strictly speaking, you don't need to set these variables, but it makes it easier to set LD_LIBRARY_PATH, which *must* be set:
Very likely you will have done much of these steps. However, using these libraries requires a different version of vic. The version that goes out with the standard distribution doesn't support the PCI video capture. ???What do we want to say here???? So you need to download a patch ???need url???? and recompile vic to be able to use this. To test, you can either run vic standalone or try running CVW and using video. Sometimes running standalone may point out any remaining errors more easily than running with CVW.
Last update: 6 August 1999
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