Intel IXP400 manual IEEE802.11 Frame Control FC Field Format, AP-STA and AP-AP Modes

Intel® IXP400 Software

Access-Layer Components: Ethernet Database (IxEthDB) API

Table 31. IEEE802.11 Frame Control (FC) Field Format

15	14		13	12	11	10	9	8	7	6	5	6	3	2	1	0
		subtype			type		protocol		order	WEP	more	pwr	retry	more	from	to DS
							version				data	mgr		flag	DS

Abbreviations:

•FC - Frame Control

•DID - Duration / ID

•SC - Sequence Control

The usage of the 802.11 frame format depends heavily on the source and immediate destination for the frame. There are four distinct possibilities:

•From STA (station) to STA.

•From STA to AP (access point).

•From AP to STA.

•From AP to AP.

The APIs in the IXP400 software focus on the two latter scenarios (AP → STA, and AP → AP).

Figure 58. AP-STA and AP-AP Modes

C					AP - STA
NPE C802.3		NPE C			AP - STA	AP - STA
B	IXP4XX		802.11
NPE B		IXP4XX		.11802	.11802
NPE A		NPE A
A		NPE B		IXP4XX
		PCI		PCI

NPE C802.3		NPE C			AP - AP
C					AP - AP
NPE B	IXP4XX			IXP4XX
A		NPE B	802.11		802.11
	IXP4XX			802.11
B
NPE A		NPE A
	PCI			PCI
	PCI

AP - AP
AP	AP
AP

B3848-001B3848-001

Conceptually, the idea of the platform running IXP400 software to operate as a “Station” and also take advantage of the 802.3 / 802.11 Frame Conversion feature has limited applicability. This scenario would entail the platform sending or receiving 802.11 formatted frames via the Ethernet NPE’s. Therefore the STA → STA and STA → AP modes are not discussed.

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	173