User Manual

84
8111A–AVR–05/08
AT86RF231
8.1.2.6 Auxiliary Security Header Field
The Auxiliary Security Header specifies information required for security processing and has a
variable length. This field determines how the frame is actually protected (security level) and
which keying material from the MAC security PIB is used (see IEEE 802.15.4-2006, section
7.6.1). This field shall be present only if the Security Enabled subfield b3, see Section 8.1.2.3
“Frame Compatibility between IEEE 802.15.4-2003 and IEEE 802.15.4-2006” on page 83, is set
to one. For details of its structure, see IEEE 802.15.4-2006, section 7.6.2. Auxiliary security
header.
8.1.2.7 MAC Service Data Unit (MSDU)
This is the actual MAC payload. It is usually structured according to the individual frame type. A
description can be found in IEEE 802.15.4-2006, section 5.5.3.2.
8.1.2.8 MAC Footer (MFR) Fields
The MAC footer consists of a two-octet Frame Checksum (FCS), for details refer to Section 8.2
“Frame Check Sequence (FCS)” on page 85.