Appendix A

Troubleshooting

Overview

This chapter provides solutions for some common problems and answers some questions you may encounter when using Communique!. If, after reading this chapter, you are unable to solve your problem, please contact MDL's Technical Support.

Common Questions about Networking

Many problems that you may encounter while using Communique! are network related. Communique! utilizes some low-level networking functions that many other applications do not require. For this reason, problems with your network configuration may not manifest themselves until you use a network intensive application such as Communique!. This section discusses several common issues that relate to network configuration or performance.

Why can't I locate other potential conference members?

If a user you wish to conference with is not included in the list of users located by the From Network scan, try selecting From Notebook on the Start Conference panel and then reselecting From Network. This will refresh the list of available conference members on your local network. The list is updated each time you select the From Network list.

If there is heavy traffic on your network, it is possible that all available network users may not respond in time to be included in the From Network list. Try refreshing the From Network list several times until your party appears. You can also use the Custom Address field to enter the user name and host name of a potential conference member.

Communique! automatically locates other possible conference members on your local network. If you wish to ensure that Communique! will detect users on remote networks, you must set up a Broadcast Tunnel. A Broadcast Tunnel is a file specifying an address or range of addresses for scanning though outside Communique!'s normal scanning range. Information on setting up a Broadcast Tunnel can be found in Appendix B, "Technical Issues".

If you are attempting to contact someone on a remote or secondary network and have not set-up a Broadcast Tunnel, the person may not appear in the Start Conference control panel and has to be added with the Custom Address entry, as described in the Chapter 2, "Conference Manager," of the Communique! User's Guide. In any case, Communique! must be able to contact the host machine of those persons with whom you wish to conference.

Why can't I contact a remote conference member?

If you are unable to contact another user, you should first attempt to ensure that you have basic network connectivity to their host. To do this, you should use the ping utility, which sends an echo request to a workstation and reports whether it was successfully received. Make sure that each host can ping all other hosts that will be included in the conference, including itself. For example, in a conference with workstations houston and orange, houston should be able to successfully do the following:

% ping houston

and

% ping orange

The other workstation, orange, should be able to do the same. A successful ping indicates only a minimal level of working networking infrastructure; there could still be problems.

What if I have multiple network interfaces on my workstation?

If you are running multiple network interfaces on one workstation, verify that the interface associated with the hostname of the workstation is up and running. Make sure that each interface has a unique hostname and verify that the hostname assigned to it is correct.

The interface lo0 is the local network loopback interface and should never be removed. Most network activity relies on this interface.

Be sure that each interface is set up properly. Use the ifconfig command to show you the current settings. Make sure each interface has its subnet mask and broadcast address set properly.

Be sure that you initialize and activate any extra network interfaces at the same time the standard interfaces are configured, and be sure you do not disable any interfaces afterwards. This is important because certain processes, such as the portmapper, should only be run after all network interfaces are configured and operating. Bringing new interfaces up (i.e., activating) or existing interfaces down (i.e., deactivating) can cause unpredictable results. In most configurations, by running ifconfig against all interfaces at the same time during system boot you start everything in the proper order.

If you are running a License Server on a machine with multiple interfaces, be sure that the license file specifies the hostname of an active interface.

What if I am using a router?

If your machine’s network connection runs across a router, the router must be able to pass TCP and UDP packets. Many routers have an option to block specified packets types. Be sure that both of the above types are enabled in both directions.

Further, be sure that the router can keep up with large amounts of data. You can test this by sending a large file (at least 1 MB in size) both ways across any routers with ftp. If you see any time-outs, Communique! may have problems as well. This especially applies when you are routing from a high speed network (such as ATM or FDDI) to a slower network (such as Ethernet). Sometimes routers cannot do packet size conversions quickly enough.

What if I am using an ATM interface card?

If you are using the TV Tool with an ATM card that relies on the workstation for packet conversion, you may experience performance problems at higher video frame rates because of the overhead required to process the incoming packets.

Check the version number of the switch software and the card revision. The card switch software must be newer or equal to the card. If it is not, you will experience severe problems using Communique!

If you are experiencing problems, try sending a large file across the ATM network using ftp. If it does not succeed, it is likely that there is a compatibility problem between your ATM card and switch software.

If you are using IP Multicast, make sure that your ATM card supports the multicast routing protocol.

Common Questions about Licensing

Why do I get "Can’t connect to license server" errors?

If you see this error, the MDL software is unable to contact the License Manager daemon (lmgrd) on the License Server. There are several situations where this error occurs.

You can obtain more detailed information about the error by examining your license.log file. This file is normally found on the machine that runs the lmgrd process. By default, it is located in the etc/insoft directory.

Verify that the workstation specified as the License Server in the license.dat file is running and is reachable by using other network commands, such as ping or telnet. If you receive "unknown host" messages, you probably have a problem with hostname resolution. If you are using DNS (Domain Name Service), the license.dat file should contain the server’s fully qualified hostname. An example of a complete hostname is host1.conglomerate.com

Verify that the insoftd and lmgrd daemons are running on the license server.

Because of security concerns, lmgrd refuses license requests from a client whose time is more than 5 minutes different from its own after time zone differences are taken into account. Make sure both machines have their dates and times set correctly, and that their time zone settings are correct.

Why do I get "inconsistent encryption code" errors?

This error indicates that there is a problem with the license key you have entered. Examine the license.dat file to verify that you have entered the correct license keys for your host. Verify that you selected the correct key type (floating or node-locked). Check to make sure that you entered the correct expiration date. Be sure your keys were generated for the correct hostid.

Why do I get "key not yet valid" errors?

This error indicates that the start date of your license keys has not yet arrived. Check your workstation’s system date to verify that it is correct.

Why do I get "license key has expired" errors?

If this error appears, then your license keys have reached their expiration date. Verify that your system date is correct. This message should only occur with temporary evaluation keys.

Why do I get "maximum number of users reached" errors?

This message indicates that no more licenses are available for the requested feature. If you have floating licenses, it indicates that all available licenses are in use by other users. You will have to wait until a user quits Communique!, releasing the license.

If you are on a node-locked workstation, the license could be claimed by an already-running Communique! application, or a defunct process failed to release its license. The root user can run the license/lmremove program found in the Communique! Install Directory or kill and restart lmgrd to release the licenses.

Why do I get "No FLEXlm nodes found to shut down" errors at boot?

This is normal. The startup scripts attempt to bring down any active license managers at system boot, assuring that there are no conflicts when the License Manager is started. The next step in the startup process runs the License Manager, and you see a message indicating that it has been started successfully.

Common Questions About Video

What compression algorithm does Communique! use?

This depends on the type of compression selected in the TV Tool control panel, which depends on the type of video capturing card installed on your workstation. Every video capture card may not directly support all compression algorithms compatible with Communique!. Compression algorithms that are currently supported include:

CellB—CellB compression was developed by Sun Microsystems to support compression and decompression of video with minimal hardware requirements. CellB is supported by all Communique! platforms.

DVE2—DVE2 compression was developed by InSoft to support compression and decompression in software. DVE2 provides a high level of image quality by taking advantage of today’s more powerful processors. DVE2 is currently available to PCs only.

Indeo—Indeo is a video codec developed by Intel. Indeo provides high image quality and very efficient software decompression. However, Indeo does not lend itself well to compressing in software, so generally you will want to use this format only if your video capture card supports Indeo compression in hardware. Indeo is currently available to PCs only.

JPEG—JPEG, developed by the Joint Photographic Experts Group, generally produces the highest quality video image, but requires more processing power than other compression algorithms.

H.261 and IP64—H.261, the ITU standard for video in conferencing environments, is a high quality, low bandwidth video compression algorithm. It produces good picture quality and consumes few network resources, but requires significant processing power to compress.

The receiving conference member does not have to support hardware decompression of the sender's compression type since Communique! can use software decompression techniques if no hardware assistance is available.

Why does the video I receive seem slow?

There are several things you can check if your video is uncharacteristically slow.

What is the quality of the source video signal being sent to you? If the incoming video signal quality is poor and full of static, the compression algorithm cannot function properly. The sender should obtain a more stable video signal through a better camera or cable connection. If the quality of the input signal can not be improved, reducing the frame rate and video frame size may help improve performance.

What frame rate has the sender selected? Each person in the conference has control over the sending frame rate. The remote conference member may have purposely (or accidentally) selected a slower frame rate.

If the person sending video has used the Bandwidth control under the TV Tool Networking options to limit his or her bandwidth consumption, be sure it has not been set at an unnecessarily low setting. For example, if the network can dedicate 512 Kbps to one person's video and that person places a self-imposed limit of 144 Kbps on bandwidth consumption, his or her video will perform below its capabilities.

What other applications are in use while the Communique! TV Tool is running? If the frame rate is high, slower workstations may not be able to reproduce the desired frame rate. If the workstation is already taxed by running other applications, the TV Tool’s performance can suffer. Try reducing the number of other applications running on the workstation.

Is network traffic high or available bandwidth constrained? Bandwidth limitations or an increase in ambient network traffic reduce the amount of information that can be sent to the conference.

Do you have enough RAM and swap space? See Chapter 1, "System Requirements," of the Administrator's Guide for your workstation's requirements. It is important to make sure that your system is configured with twice as much swap space as it has RAM.

Certain video compression schemes are processor intensive and work best when assisted by dedicated hardware (e.g., JPEG video). Without the appropriate hardware assistance, you may see less than optimal video performance. You may wish to ask the video sender to select CellB as their video compression format. CellB is not processor intensive and is ideal for reception on platforms without dedicated video hardware.

Why can't others see my video?

There are several conditions that could cause your video to appear as a black window, or prevent you from sending video at all. You should check the following items to ensure that the TV Tool and your video source are set up properly.

Enable the Local Monitor option and verify that your video card and equipment are functioning properly.

Make sure that your video source is connected to the video input jack that you have selected in the TV Tool Video options window.

Have you disabled video transmissions from the TV Tool control panel? You must click on the TV Tool's Start button to begin sending video from your workstation.

Have you selected the desired conference member(s) to receive video from the TV Tool's Members option? You should verify that the user not receiving your video is in the "Offer Video To" list and click Apply to make the changes take effect.

Is there a problem with your video equipment or cabling? Verify that the video source is connected to the TV Station properly. Try using another video source or connect your video source to another output such as a television display to verify that it is operating properly.

Have you correctly installed your video card and any necessary drivers? Most video capture cards come with demonstration or test programs that you can use to verify correct installation of the video card.

Is the correct video card selected in the TV Tool control panel? The TV Tool control panel allows you to select from several different types of video capture cards, even if they are not installed on your workstation. Contact your system administrator if you are not sure which type of video card is installed on your workstation.

There may be a problem with the network configuration. Verify correct network configuration as outlined in the "Common Questions about Networking" section.

Why does the video I receive seem distorted or grainy?

Communique! employs various types of data compression techniques to conserve network bandwidth and increase the video frame rate. The compression algorithms the sender can use depend on the type of video card in use. JPEG can generally produce much higher quality video, but requires more network bandwidth and consumes more system resources to decode than CellB. IP64 can produce video similar in quality to JPEG, but at a much lower network bandwidth and higher cpu load. Ask the sender to choose another compression method to compare its performance with the video you are currently receiving.

Be aware that not all video cards have the same capabilities. Some video cards, such as the SunVideo card, produce a different level of video quality than others, such as those from Parallax. The quality of image is directly related to the compression and display hardware contained on the card. In addition, the quality of the video source can have a dramatic effect on the quality of the video received and the network bandwidth used. Some inexpensive cameras are inconsistent in the brightness levels or colors they capture, which creates havoc with compression algorithms.

What compression settings have been selected on the sender's TV Tool Video options? Every person in the conference controls their own video compression settings. As the amount of compression increases, the quality of the image that is sent is reduced. The remote conference member may have purposely (or accidentally) selected a higher compression setting, which could have a dramatic effect on image quality.

What is the quality of the source video signal being sent to you? If the incoming video signal quality is poor and full of static, the image you receive will be poor. The sender should obtain a more stable video signal through better connection or higher quality video source.

Why do I see color flashing when I move among windows?

On workstations with 8-bit color, the video image must share a color palette with all other applications. Since there are only 256 colors available, the video window creates its own private colormap, active only when the window is selected. You may experience color flashing in the Local Monitor or TV Viewers. From the TV Viewer options you can select Suppress Color Flashing to eliminate the flashing. However, this reduces the number of colors available and thus the quality of the video. If your workstation has the ability to run in a 24-bit display mode, you may be able to eliminate this problem completely.

Common Questions About Audio

Why does the audio I receive seem loud?

Problems with audio volume can originate with the sender or receiver, so it is important to check the settings on both ends to track down any problems that may occur.

First, check your Playback Volume setting to make sure that it is not too high. This option controls the volume level of the audio you hear. Reduce the playback volume to a reasonable level.

If you have external speakers, make sure the volume is adjusted to a reasonable level.

Every person in the conference has control over their own sending volume. If one person’s audio seems to be louder than the other audio that you hear, ask that person sending the loud audio to reduce their sending volume.

Some microphones feature an adjustable gain control. If the sender is using such a microphone and adjusting the sending volume has little effect, ask that person to adjust the gain appropriately.

What is the level of the sender's input audio signal? If the level is too high it will overload the workstation's audio inputs, producing a loud muffled sound or severe clipping. This situation occurs if the sender is using audio input from a line-level device (such as a VCR) connected through the microphone-in port of the workstation. See the Audio Input Devices section of Chapter 2, "Installing Optional Hardware" for more information.

Why don't other people in the conference hear me?

Ask each person who can't hear you to use the AudioScope to see if they are receiving audio from you. The AudioScope can be launched from the Audio menu in the Audio Tool.

You may have muted your audio from the Audio Tool. Bring up the Audio Tool control panel and verify that the mute option has not been enabled.

Your sending volume may be too low. Adjust the sending volume level for the Audio Tool to a reasonable level.

The remote conference member's playback volume may be too low to hear you. Have conference members verify that their playback volume is set to a reasonable level in the Audio Tool's control panel. Have them check the connection and volume setting of any external speakers they are using.

Have you selected the desired conference member(s) to receive audio from the Audio Tool's Members option? You should verify that the user not receiving your audio is in the "Offer Audio To" list and click on Apply to make the changes take effect.

The other member(s) may be refusing your audio. Have them check their Members option and verify that they are accepting audio from you.

Your microphone may not be connected correctly, or may be defective or in need of a new battery. Verify that the microphone is on and connected to the microphone-in port of your workstation. You can use enable Local Monitor from the Audio Tool's Device options to verify that your microphone is functioning properly.

Open the AudioScope and verify that when you speak the green bar moves, indicating that the Audio Tool is capturing audio. You will also want to make sure that the green bar stays above the Silence Sensor’s indicator (the red line) when you speak.

You may have selected the wrong input device. Check the Audio Tool's Device options and verify that you are using the selected input device.

Your Silence Sensor may be set too high. Try reducing the level of the Silence Sensor from the Audio Tool's Advanced options.

Another application may have gained control of the audio port. Only one application at a time can access the audio port, so you need to terminate any other applications which attempt to use the audio port.

The Echo Cancellation value in the Audio Tool's Advanced options may be set too high. If the Silence Sensor is set too low and the Echo Cancellation too high, no one will be able to speak without Echo Cancellation cutting them off. This doesn't happen often, but the situation could arise if your microphone or speaker produces a constant hum that confuses the Echo Cancellation process.

Why don't I hear other conference members?

Use the AudioScope to see if you are receiving audio from other conference members.

Which audio output device is selected in the Audio Tool's control panel? Make sure that the output device that you wish to use is selected.

Your playback volume may be set too low to hear other conference members. Verify that your playback volume has been set to a reasonable level in the Audio Tool.

The remote conference member may not be sending you audio. Have the members you are not hearing check their Members window and verify that you are being offered audio.

You may be refusing their audio. Check your Members window and verify that you are accepting audio from that person.

The remote conference member may have a problem sending audio. Refer to the section "Why don't other people in the conference hear me?".

Your speaker may be defective or your external speakers may be connected incorrectly. Verify that the speaker or speaker box is functioning correctly.

If you are using an external speaker, is it on? Verify that it is connected properly. If it uses batteries, are they dead? If your external speakers connect to the workstation through the headphone port, then verify that Headphones is selected in the Audio Tool Device options.

There may be a problem passing audio data through the network. Refer to the Common Questions About Networking section to verify that your network is functioning properly.

Another application may have gained control of the audio port. Only one application at a time can access the audio port, so you need to terminate any other applications which attempt to use the audio port.

The Echo Cancellation value in the Audio Tool's Advanced options may be set too high. If the Silence Sensor is set too low and the Echo Cancellation too high, no one will be able to speak without Echo Cancellation cutting them off. This doesn't happen often, but the situation could arise if your microphone or speaker produces a constant hum that confuses the Echo Cancellation process.

Why do I hear an echo of myself or feedback?

This situation occurs when your voice is picked up from a remote user's speaker by the microphone and retransmitted into the conference. This loopback can be minimized and prevented in several ways.

Ask the remote conference member to move the microphone away from the speaker. If the person is using an external speaker, ensure that it points away from the microphone.

Reduce your Sending Volume or have the remote conference member reduce playback volume.

Ask the remote conference member to raise the Silence Sensor. This decreases the likelihood that the remote microphone picks up sound from the conference member's speaker.

Try increasing the Echo Cancellation value from the Audio Tool's Advanced settings.

One way to eliminate echo in your audio is to use the MDL Call Port, which uses digital signal processing technology to eliminate any echo from the audio signal that it sends out.

Why does the audio sound choppy or clipped?

Make sure that the person using the microphone is speaking clearly into the microphone and from no more than a foot away. Most high quality microphones, including those available directly from MDL, are unidirectional. Unidirectional microphones only pick up sound originating directly in front of them. If you turn your head from side to side or walk around the room, the microphone will not pick up your voice consistently.

The person sending audio may have the Silence Sensor level set too high. Often, as conference participants speak, their voices drop down in volume on some syllables, especially at the ends of words. The Silence Sensor recognizes these dips in volume as silence and does not send them to the conference. Ask the person whose audio is clipping to reduce the level of the Silence Sensor. The Silence Sensor's controls are available in the Advanced dialog box available from the Audio Tool's Options menu.

If your network is very busy, try reducing the level of the A/V Sync slider in the Audio Tool's Advanced dialog box. If Communique! is unable to synchronize your video and audio, it may drop some of the audio information.

If there are several other people involved in the audio conference it is critical to properly set the Silence Sensor control to the proper level.

Why do I hear lots of background noise or constant humming?

What type of microphone is being used? Lower quality microphones are often omnidirectional. Omnidirectional microphones pick up sound from all directions and are likely to give unsatisfactory results. A high-quality, unidirectional noise cancelling microphone is available directly from MDL.

Some low quality or damaged microphones are not adequately grounded. This could cause a constant humming sound to be input into the conference. Try to locate the offending equipment and replace it.

If you are using external speakers, a buzzing sound could be caused by electrical interference. If you cannot eliminate the source of the interference, try reducing the treble controls (if available on the external speakers) to reduce high frequency noise.

The Silence Sensor level of the person sending audio may be set too low. The Silence Sensor allows the microphone to send audio only above a given threshold, ideally when someone speaks. By raising the level of the Silence Sensor, you can filter out a good portion of the low level background noise.

If you are using compressed audio, you should expect some loss of audio quality.

How Can I Minimize My Bandwidth Consumption?

By reducing the amount of network traffic you generate, you speed things up for other network users, improve Communique!'s performance in low bandwidth conditions, and speed up Communique!'s functions. There are several things you can do to reduce the amount of network bandwidth that you use.

Video Frame Size—The larger the video frame size, the more video data that must be transmitted across the network. Lowering frame size reduces network traffic. Shrinking the video window size also gives you more space on the desktop.

Video Frame Rate—Bandwidth usage is directly proportional to the video frame rate. Reducing the frame rate greatly reduces the amount of traffic being generated.

Video Compression—By increasing the amount of compression being used on your video signal, you significantly reduce the amount of bandwidth you use. Increasing the amount of compression reduces the quality of the video image, but often a slight increase in compression yields dramatic bandwidth reduction with only a modest decrease in image quality.

Bandwidth Controls—By selecting a Bandwidth setting from the TV Tool's Network options, you specify the maximum bandwidth that your video consume. This setting governs the bandwidth generated by your video stream.

Multicast Routing—One way to decrease the amount of bandwidth used in multipoint conferences is to use the IP Multicast routing protocol. The Audio tool, TV Tool, and Speaker Phone all support IP Multicast. Multicast works by reducing the number of data streams sent by each conference member. Rather than sending a stream of either audio or video data to each member, under multicast the users will send only one stream, and everyone who the data is intended for will automatically pick it up. This reduces both bandwidth usage and the system load on the sending machine.

Audio Compression—By enabling audio compression from the Audio Tool, you can reduce the bandwidth used by audio significantly. There is a slight reduction in audio quality with compression enabled, but compression may be necessary if network resources are highly constrained.

Silence Sensor—By keeping the Silence Sensor set as high as possible—so that you are not transmitting audio data when you are not speaking—you lower the amount of network traffic you generate. You must avoid setting it too high or you will adversely affect audio quality.

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