I talked with a Sniffer Tech who said that the Octets alarm is one which monitors the number of packets traversing that network segment. It is a configuable limit based on the individual segment and is meant to alarm when resources are getting close to max. It is a default setting and may be geared toward a 10Mb link than a 100Mb, and may need adjusting.
If you are seeing slowdowns during those times, perhaps you have something else going on. Keep an eye on the port stats of the segments and watch for spikes.
-Arnie