11 WLANs must be able to form and re-form their membership
constantly, and because radio transmission conditions themselves can change, coordination
becomes a large issue in WLANs. Management and control packets are dedicated to these
coordination functions. In addition, the headers of ordinary data packets contain a great
deal more information about network conditions and topology than, for example, the
headers of Ethernet data packets would contain.
Guide to Wireless LAN Analysis
29
802.11 MAC header (WLAN)
Frame
Control
Duration
ID
Address
1
Address
2
Address
3
Sequence
Control
Address
4
2 Bytes 2 Bytes 6 Bytes 6 Bytes 6 Bytes 2 Bytes 6 Bytes
802.3 MAC header (Ethernet)
Dest.
Address
Source
Address
Type or
Length
6 Bytes 6 Bytes 2 Bytes
A complete breakout of all the fields in the packet headers and the values they may
take is beyond the scope of this chapter. For this overview, Table 2.5 below presents a list
of the types of information 802.11 WLAN data packet headers convey. The table also
shows the types of information carried in management and control packets.
2.2.8.2 Management and Control Packets
Control packets are short transmissions which directly mediate or control communications.
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