Frame Control FC

Identifies what kind of frame this is and carries the flags that change how the rest of the header is read.

Reading a capture

The first field of nearly every frame and the one to read first. Type and Subtype tell you what you are looking at; To DS and From DS tell you how to interpret the three address fields that follow.

Subfields

• Protocol Version — Always 0 for every version of the standard published so far.
• Type — The broad class of frame.
• Subtype — The specific frame within its type. Read together with Type — a subtype value means nothing on its own.
• To DS — Set when the frame is destined for the distribution system.
• From DS — Set when the frame is coming from the distribution system.
• More Fragments — Set when further fragments of this MSDU follow.
• Retry — Set when this frame is a retransmission.
• Power Management — Indicates the sending station's power save state after this exchange completes.
• More Data — Set by an AP to tell a dozing station that more frames are buffered for it.
• Protected Frame — Set when the frame body has been encrypted.
• +HTC/Order — Indicates an HT Control field is present. Its meaning has changed across amendments, which is why it carries two names.

Where it sits

QoS Data MPDU > Frame Control

• Open in the explorer — Ack
• Open in the explorer — TCP over IPv4, in a protected QoS Data frame, aggregated
• Open in the explorer — Association Request
• Open in the explorer — Association Response
• Open in the explorer — Beacon
• Open in the explorer — Compressed Block Ack
• Open in the explorer — CTS
• Open in the explorer — Four-way handshake message 1
• Open in the explorer — Four-way handshake message 2
• Open in the explorer — Four-way handshake message 3
• Open in the explorer — Four-way handshake message 4
• Open in the explorer — Probe Request
• Open in the explorer — Probe Response
• Open in the explorer — ARP request in a QoS Data frame
• Open in the explorer — ICMP echo over IPv4, in a QoS Data frame
• Open in the explorer — UDP over IPv6, in a QoS Data frame
• Open in the explorer — TCP over IPv4, in a protected QoS Data frame
• Open in the explorer — TCP over IPv4, in an open QoS Data frame
• Open in the explorer — UDP over IPv4, in a QoS Data frame
• Open in the explorer — RTS
• Open in the explorer — Trigger frame

Accuracy

Clause

802.11-2024 §9.2.4.1

Byte order

little-endian — least significant octet first

Verified

Not verified against the standard. Treat this as a claim, not a fact.