TCP over IPv4, in a protected QoS Data frame, aggregated

The identical MAC frame and payload, carried by 802.11ax instead of 802.11a. Every lane below the PHY is the same file as the non-HT composition — only the top one differs.

Not carried in 4 other formats
Find a frame
PHY
Class
Mechanism

Everything here is true proportion on each lane's own axis. Labels float above their field and step down a row only where they would collide, so nothing is inflated to make its name fit. Zoom widens the whole diagram together and scrolls sideways, which keeps the lanes aligned.

PHY 802.11ac Wi-Fi 5 µs
MAC octets

this whole lane is the PSDU, inside the Data field above

MAC octets

this whole lane is the MPDU, inside the A-MPDU subframe above

Not in this frame: Address 4 — Both To DS and From DS are 1. An absent field takes no octets at all; what follows moves up to meet what came before.

SEC octets

this whole lane is the Frame Body above it

LLC octets

this whole lane is the Encrypted Data above it

NET octets

this whole lane is the Payload above it

TSPT octets

this whole lane is the Payload above it

The Data slot is open — nothing is stacked below this lane yet. A truncated stack is a valid composition, not a broken one.

How the layers combine

Each layer names the unit it receives from above differently from the unit the layer above hands down. They are the same octets. Nothing is added crossing a seam — the header you see appear was always inside the slot, and only becomes visible when the next layer subdivides it.

  1. PPDU = L-STF + L-LTF + L-SIG + VHT-SIG-A + VHT-STF + VHT-LTF + VHT-SIG-B + DATA ⊃ PSDU
    the PSDU keeps its name — A-MPDU does not rename it, it shows the structure that was always inside it
  2. PSDU = Subframe 1 ⊃ MPDU + +N more
    the MPDU keeps its name — QoS Data frame does not rename it, it shows the structure that was always inside it
  3. MPDU = FC + Dur + A1/RA + A2/TA + A3 + SeqCtl + QoS + Body + FCS
    the MSDU is wrapped by CCMP-128 protection — a header and trailer around the same payload
  4. CCMP = CCMP Hdr + Ciphertext + MIC
    the MSDU is the LPDU — same octets, different name byte order flips to network order ; bit 0 moves to the other end of the octet
  5. LPDU = DSAP + SSAP + Control + OUI + EtherType + Payload
    the Payload is the Datagram — same octets, different name
  6. Datagram = Version + IHL + DSCP + ECN + Total Length + Identification + Flags + Fragment Offset + TTL + Protocol + Header Checksum + Src + Dst + Payload
    the Payload is the Segment — same octets, different name
  7. Segment = SrcPort + DstPort + Seq + Ack + Data Offset + Reserved + Flags + Window + Checksum + Urg + Data

Select any field to read what it is and why it matters.

Every field, and what contains what

The same frame as a hierarchy rather than a scale drawing. Proportion is useful for airtime and useless for structure — a one-bit flag and a 1500-octet payload matter equally here and not at all equally above.

Structure

Every field in this transmission and what contains what — one hierarchy from the PPDU on the air down to the application's bytes. Indentation is containment. 129 fields, 129 unverified.