Installation guide

Wireless Guide 133
Advanced Features for Wireless Analysis
Filters for Wireless LAN Error Packet Types
You can set filters on the wireless LAN error packet types listed and described
in Table 10-10.
Protocol Decodes for Wireless Networks
In addition to all upper layer decodes, the Sniffer software provides
comprehensive decodes for 802.11 wireless LAN traffic. Since wireless LAN
services take place at the physical and MAC layers, you can see the
wireless-specific decodes by examining the DLC layer in the Decode display.
Table 10-10. Wireless LAN Error Packet Types Available for Filtering
Packet Type Description
PLCP Errors PLCP errors occur when a wireless station
receives a Physical Layer Convergence
Protocol header with an invalid checksum.
Before frames are sent between wireless
stations, the physical layer (PHY) sends a PLCP
header to a receiving station to negotiate the
size of the frames to be sent, the speed at which
they should be sent, and so on. This PLCP
header includes a checksum which the
receiving station uses to validate that the
received PLCP header is not corrupt. If this
checksum is corrupt, it is considered a PLCP
error.
WEP ICVs The Wired Equivalent Policy (WEP) is used to
encrypt data sent between stations on the
wireless network. When two stations exchange
WEP-encrypted data, they go through an
authentication sequence wherein challenge
messages are encrypted and decrypted by
sender and receiver. If an Integrity Check Value
does not match between sender and receiver,
the receiver sends a frame indicating a
communications failure (that is, an invalid WEP
ICV). This filter works on these types of packets.