Appendices
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Problem: The mouse pointer of the ServSwitch Agility receiver is slow or sluggish when moved
across the screen.
This issue is often related to either using dithering on the video output of one or more transmitting computers or using VGA-to-
DVI video converters.
Dithering is used to improve the perceived quality and color depth of images by diffusing or altering the color of pixels between
video frames. This practice is commonly used on Apple Mac computers using ATI or Nvidia graphics cards. VGA-to-DVI converters
unwittingly produce a similar issue by creating high levels of pixel background noise.
ServSwitch Agility units attempt to considerably reduce network traffic by transmitting only the pixels that change between
successive video frames. When dithering is enabled and/or VGA-to-DVI converters are used, this can have the effect of
changing almost every pixel between each frame, thus forcing the ServSwitch Agility transmitter to send the whole of every
frame: resulting in greatly increased network traffic and what’s perceived as sluggish performance.
Remedies:
• Linux PCs
Check the video settings on the PC. If the Dither video box option is enabled, disable it.
• Apple Mac with Nvidia graphics
Use the Black Box utility for Mac’s – Contact technical support.
• Apple Mac with ATI graphics
Use the ServSwitch Agility Dual series unit with Magic Eye dither removal feature.
• Windows PCs
If you suspect these issues with PC’s, contact technical support for assistance.
• Replace old VGA adapters on host computers with DVI video cards.
Problem: ServSwitch iPath cannot locate working ServSwitch Agility units.
There are a few possible causes:
• The ServSwitch Agility units must be reset back to their zero config IP addresses for ServSwitch iPath discovery. If you have a
working network of ServSwitch Agility unit’s without ServSwitch iPath and then add ServSwitch iPath to the network, the iPath
manager will not discover the ServSwitch Agility units until they are reset to the zero config IP addresses.
• This could be caused by Layer 2 Cisco switches that have
Spanning Tree Protocol (STP)
enabled but do not also have
port-
fast
enabled on the ports to which ServSwitch Agility units are connected. Without portfast enabled, ServSwitch Agility units
will all be assigned the same zero config IP address at reboot and ServSwitch iPath will only acquire them one at a time on a
random basis.
You can easily tell whether portfast is enabled on a switch that is running STP: When you plug the link cable from a working
ServSwitch Agility unit into the switch port, check how long it takes for the port indicator to change from orange to green. If it
takes roughly one second, portfast is on; if it takes roughly thirty seconds then portfast is disabled.
Remedies:
• Ensure that the ServSwitch Agility units and the ServSwitch iPath manager are located within the same subnet. ServSwitch
iPath cannot cross subnet boundaries.
•
Manually reset
the ServSwitch Agility units to their zero config IP addresses.
• Enable portfast on all switch ports that have ServSwitch Agility units attached to them or try temporarily disabling STP on the
switches while ServSwitch iPath is attempting to locate ServSwitch Agility units.
