Peavey MediaMatrix Nion, Hardware Manual

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NION Hardware Manual
September 30, 2010 Version 1.6.1.0 63
The CM-1 firmware, up to and including version 2.9.16, contains a bug. This bug will allow a
stack overflow to occur during times of excessive network traffic that will render the CM-1
inoperative. A fix is not currently available, but is being worked on. This problem can occur in
any CM-1 module installed in a NION, CAB or Mainframe.
Note: The CAB 4n is available with both CM-1 and CM-2 modules. Only CM-1 modules are
affected.
Verification of the problem - all conditions will be present
ƒ The CM-1 will initially work properly.
ƒ The CM-1 will become unresponsive. This can be indicated by an inability to change
bundles.
ƒ An HF2 related error will be logged.
ƒ All audio bundles in and out of the CM-1 will stop.
ƒ The CobraNet interface will not show active in CobraNet Discovery.
ƒ The LED indicators on the CobraNet RJ-45 Ethernet connectors will most likely be static
and in a random state. They will not be blinking in the normal pattern that indicates
CobraNet activity. In some cases, the lights will blink in a repeatable pattern of 7,6,2.
ƒ A hardware reset will correct the problem.
The causes of firmware malfunction
Presence of excessive network traffic, also known as a data storm , can cause a stack overflow
to occur. A data storm can be caused by the presence of a loop in the network. Loop problems
can be more acute in larger networks and in networks that contain gigabit Ethernet links. A
data storm can also be caused by malfunctioning equipment in rare cases.
Some devices will transmit multicast data in normal operation. In a large network, if many or
all devices on the net do so by coincidence at the same time, a condition similar to a data storm
can occur and have similar consequences for a brief instant.
To put it in audio terms, a network loop is analogous to an audio feedback loop. The screech
one hears in audio feedback is due to continuous positive reinforcement of the signal. A
network loop causes a similar positive reinforcement of the data. Data packets are replicated
and increase in quantity with each hop through a switch until all available network bandwidth
is consumed.