802.11 Protocol Architecture
The timestamp field is used in an IBSS to keep stations’ clocks
synchronized and to prevent clock oscillation since all participating
stations have the responsibility of transmitting beacons. IBSS stations
will only reset their clocks based on timestamp values greater than their
own clocks, and the timestamp field is also used by stations in an IBSS
to make other stations aware of the latest BSS parameters. If a beacon
or probe response is received from an IBSS that has parameters that
differ from those that the station has on record, it will adopt the new
values only if the timestamp field is newer than the timestamp that was
associated with the most recent beacon or probe response data of which
the station has a record. This is not true of a BSS. The access point
could literally roll its clock backwards and the infrastructure would still
work.¹ A sample protocol analyzer trace in Figure 2.6 shows the
timestamp field below.
1
IEEE 802.11 - 1999 (R2003) – Section 11.1.1.1, 11.1.4
