Sniffer® Portable Professional User's Guide - NetScout

Defining Filters and Triggers
Filters for 802.11 Packet Types in the Advanced Tab
When using Sniffer Portable Professional with a wireless adapter, the
Packet Type dropdown includes the wireless LAN error packet types
listed and described in Table 10-1.
Table 10-1. 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.
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