Installation guide

Wireless Guide 151
Advanced Features for Wireless Analysis
 1 — Unspecified reason.
 4 — Disassociated due to inactivity.
 5 — Disassociated because the access point is unable to handle
all currently associated stations.
 7 — Class 3 frame received from non-associated station.
 8 — Disassociated because sending station is leaving (or has left)
the network.
 9 — Station requesting (re)association is not authenticated with
responding station.
Mcast/Bcast Fragmentation
The Expert generates the Mcast/Bcast Fragmentation alarm when it detects
an 802.11 frame with a multicast or broadcast destination address and
fragmentation indicated in the MAC header. This is a violation of the 802.11
specification.
Wireless networks commonly implement the fragmentation and
defragmentation services provided by the 802.11 MAC layer to increase
transmission reliability. However, the 802.11 specification does not allow
fragmentation for broadcast or multicast frames because of the overhead this
would cause for the network as a whole.
Missing Fragment Number
The Expert generates the Missing Fragment Number alarm when it detects
a jump in the fragment number of an 802.11 frame, indicating that a portion of
a fragmented data unit is at least temporarily missing.
Wireless networks commonly implement the fragmentation and
defragmentation services provided by the 802.11 MAC layer to increase
transmission reliability. When a unicast frame’s length exceeds an internal
threshold in the MAC’s MIB, the MAC will break up the frame into smaller
constituent frames — fragments — with the same sequence number.
Each fragment of a larger data unit is identified with a fragment number
indicating its intended ordered position within the reassembled data unit at the
receiving station. The Expert observes each transmitted fragment and stores
the fragment numbers. If it observes a jump in the fragment number for the
transmission of fragments with the same sequence number, it generates this
alarm.