37
FUR
THER
INFORMA
TION
Problem: The audio output of the ALIF receiver sounds like a scratched re-
cord.
This issue is called Audio crackle and is a symptom of the same problem that produces
blinding (see previous page). The issue is related to missing data packets.
Remedies:
As per blinding discussed previously.
Problem: AIM cannot locate working ALIF units.
There are a few possible causes:
• The ALIF units must be reset back to their zero config IP addresses for AIM discovery.
If you have a working network of ALIF’s without AIM and then add AIM to the network,
AIM will not discover the ALIFs until they are reset to the zero config IP addresses.
• This could be caused by Layer 2 Cisco switches that have
enabled but do not also have
portfast
enabled on the ports to which ALIF units
are connected. Without portfast enabled, ALIF units will all be assigned the same zero
config IP address at reboot and AIM 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 ALIF 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 ALIF units and the AIM server are located within the same subnet
because AIM cannot cross subnet boundaries.
•
the ALIF units to their zero config IP addresses.
• Enable portfast on all switch ports that have ALIF units attached to them or try
temporarily disabling STP on the switches while AIM is attempting to locate ALIF units.