Sniffer® Portable Professional User's Guide - NetScout

Chapter 8
212 Sniffer Portable Professional
Table 8-9. 802.11 Counters in the Statistics Tab (2 of 2)
Counter Description
802.11 Short PLCPs The number of Physical Layer Convergence
Protocol (PLCP) protocol data units seen with
the “short” preamble and header during this
capture session. This form of PLCP PDU is
used to achieve higher throughput and can
support 5.5 and 11 Mbps transmission
speeds.
802.11 Long PLCPs The number of PLCP PDUs seen with the
“long” preamble and header during this
capture session. This form of PLCP PDU is
compatible with legacy equipment from
older wireless LANs and supports and
operates at either 1 Mbps or 2 Mbps.
Data Rate Counters These counters vary depending on the
monitored network:
• For 802.11b/g networks, there are
separate counters for the number of
frames sent at 1, 2, 5.5, 11, 6, 9, 12,
18, 24, 36, 48, 54, 72, 108 Mbps.
• For 802.11a networks, there are
separate counters for the number of
frames sent at 6, 9, 12, 18, 24, 36, 48,
54, 72, and 108 Mbps.
• For legacy 802.11b cards, the speeds
remain at 1, 2, 5.5, 11 Mbps.
NOTE: 802.11g is backward-compatible with
802.11b, therefore the speed counters seen
in 802.11b are also shown in 802.11g.
802.11b and 802.11g share the same
frequency band (2.4 GHz) and same number
of channels (1-14). 802.11b goes from
speeds 1 Mbps to 11 Mbps and 802.11g goes
from speeds 1 Mbps to 54 Mbps. 802.11a
and 802.11g share similar speeds (6, 9, 12,
18, 24, 36, 48, 54, 72, and 108 Mbps – 72
and 108 Mbps are proprietary
implementations).