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This chapter discusses problems you may encounter when configuring the VTA and suggests actions you can take to solve these problems.
This indicates that the VTA is not properly connected to the power source. Make sure the power cable is firmly connected to the VTA and to the power outlet.
This indicates that the LAN port is not connected to the network segment. Make sure that the connections are secure, you are using a correct Ethernet cable and connector, and the devices at both ends of the Link are powered-up. For the LAN connector pin-out, see the
Indicates that there is a probable configuration problem at one end. Check each configuration for the proper phone number, IP address, subnet mask and default router address.
Check the registration list on the gatekeeper and make sure that each endpoint is registered there.
Make sure that the additional phone numbers created by the VTA do not conflict with other numbers assigned.
After the previous call, the VTA did not drop the session properly. Turn off the VIU-323 and turn it back on.
Check the gatekeeper endpoints list and make sure that each endpoint is registered; then check the VTA registration at both ends.
Check the network connection by pinging the far end VTA; if the ping fails, there is a network problem; if the ping succeeds, turn off the room systems at both ends and turn them back on; if this still does not work turn off the VTAs at both ends and turn them back on.
These problems usually indicate a poor network connection. Try making the call at a lower speed, if possible, or try making the call during off-peak hours.
If the above suggestions solve this problem, there is a network problem that you should check.
Check the dialing stream to make sure the gateway prefix is correct.
Check that both ends of the call are set at the same bandwidth; if required, adjust the bandwidth using the correct prefix.
If after trying the above solutions, the problem persists, try the following procedures:
To assess the network connection, use the ping command:
Step 1 Working from a PC or UNIX system that is on the same segment as one of the failing VTA, ping the IP address of the far-end VTA. The ping command indicates if there is network connectivity and provides the round-trip delay time. Run the ping command a few times or let it run continuously for a minute to see if connectivity is consistent. Also note the round-trip delay variation.
Step 2 Run the ping command, using the gatekeeper's IP address as the destination.
You send a ping command from a Windows PC to a VTA to see if the VTA is properly connected to the LAN.
To send a ping command, perform the following steps:
Step 1 On the Windows PC, click Start>Programs>Command Prompt or Programs>MS-DOS prompt.
Step 2 In the window that opens, type ping followed by a space and the IP address of the VTA you want to check (for example, ping 123.30.80.48).
Reply from messages appears on the screen, the VTA is connected. In this case, type Exit and press Enter to close the window.
To see if the problem lies with the gatekeeper, try a direct VTA-to-VTA call:
Step 1 Set up two VTAs to connect directly to each other rather than through the gatekeeper.
Step 2 Configure the VTAs to point to each other:
(a) Run Cisco IP/VC Configuration Utility on a PC and specify the IP address of one of the VTAs.
(b) Advance to the Network Parameters dialog box and change the Default Gatekeeper ID to the address of the destination VTA.
(c) Save and transfer this configuration.
Step 3 Make the same change on the destination VTA, specifying the source VTA's IP address as the default gatekeeper.
Step 4 Try the call again.
Try a VTA-to-VTA call with both VTAs on the same LAN segment to see if the problem is within the equipment itself (if this is not possible, for example, if the equipment is remotely located, skip to the next topic):
Step 1 Set up the VTAs to connect directly to each other rather than through the gatekeeper. This may involve moving one system onto the local segment. Modify the IP address of the moved VTA to a value appropriate for the local segment.
Step 2 Configure the VTAs to point to each other:
(a) Run Cisco IP/VC Configuration Utility on a PC and specify the IP address of one of the VTAs.
(b) Advance to the Network Parameters dialog box and change the Default Gatekeeper ID to the address of the destination VTA.
(c) Save and transfer this configuration.
Step 3 Try the call again.
If problems disappear on the local segment but return as soon as you involve the larger network, the problem may lie in the network itself. There are several tests you can run to troubleshoot problems between remote sites, even if you are unable to test local video conferences.
Step 1 Reduce the speed of the videoconference to the lowest level possible (64K or 128K). If the videoconference runs well at this lower speed (admittedly with poorer video quality) but has problems at higher speed, the network is suspect.
Step 2 Try the video conference at different times of day. Because network use varies over a 24-hour period, video conferences may work better at some times of day than others. If you find a video conference works well during "off" hours, such as early morning, but fails at busy times (typically late morning or mid afternoon), the network is suspect.
Step 3 Try a network route that has fewer router hops, such as across a leased line or an alternate ISP. To determine the number of router hopes, run a traceroute (tracer Ipaddr on a PC, tr Ipaddr on a UNIX system). If the video conference behaves better on a connection with fewer routers, the network is at fault.
To establish a terminal session between the PC and the VTA:
Step 1 Make sure the VTA is turned off.
Step 2 Connect the 9-pin male connector of the null modem cable to the console (serial) port on the front panel of the VTA and connect the cable's nine-pin female connector to the configuration PC's COM 1 port (alternately, you can connect the cable's 25-pin male connector to the PC's COM 2 port, but this may require a female/female adapter).
Step 3 Use Windows HyperTerminal or a similar application to open a console session. Set the following parameters for Windows HyperTerminal:
Step 4 Turn on the VTA to start a terminal session. The message: "Press any key to start configuration" appears (if no message appears, press Ctrl-X and wait for the message). Press any key within six seconds of receiving the message to display a menu of configuration options.
Step 5 Enter 1 (the number 1) and press Enter; again enter 1 (the number 1) and press Enter.
Step 6 Enter the IP address for Interface No. 1 and press Enter (the address must be entered in dotted decimal format without leading zeroes, for example, 170.4.10.20).
Step 7 Enter the default router IP address and press Enter (the address must be entered in dotted decimal format without leading zeroes, for example, 170.4.10.20).
Step 8 Enter the IP subnet mask in hexadecimal notation and press Enter. The PC then displays configuration information and the VTA automatically reboots.
Step 9 When Ready appears on the PC, disconnect the cable that connects it to the VTA and close the terminal session.
After you set the IP addresses, run the Configuration Utility. Note that the Select Unit screen will display the IP address of the VTA that you defined above in the list of IP/VC 3500 units. Select it from the list and continue to configure the VTA. You will notice that the IP addresses defined above will appear in their appropriate screens during the configuration procedure.
Posted: Fri Nov 12 19:51:06 PST 1999
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