Protocol for communication between access ports and wireless switches

Abstract

A wireless local area network includes access ports which communicate over a wired network with wireless switches which control the access ports and bridge data between portals in the access ports and another network. Code for operating the access ports and for configuring the portals is separately downloaded from the wireless switch. Where an access port includes more than one portal, separate ethernet addresses are assigned to the processor of the access port and to the portals for communications with the wireless switch. The protocol may provide separate sequence numbers for the communications and include a command field.

Description

BACKGROUND OF THE INVENTION

This invention relates to wireless local area networks such as those following the protocols of IEEE Standard 802.11. In particular this invention relates to networks arranged to use wireless switches and access ports, such as the networks described in copending application Ser. No. 09/528,697, filed Mar. 17, 2000, the specification of which is incorporated herein by reference. It should be understood that the term “access port” as used in this application is the commercial name for the device referred to as an “RF Port” in the referenced copending application and the term “wireless switch” as used in this application is the commercial name for the device referred to as “Cell Controller” in the referenced copending application. The wireless switches of the present invention may also correspond to the cell controllers described in copending provisional application Ser. No. 60/473,755, filed May 28, 2003, the specification of which is incorporated herein by reference.

New technologies are currently evolving that make it desirable to support different communications protocols and different media using the wireless switches, to interface additional devices to the wired network containing the wireless switch by radio, fiber optics or serial data paths using other media, including wires.

It is an object of the present invention to provide a new and improved communications format that can accommodate multiple technologies in connection with communications between a wireless switch and an access port.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided an improved method for configuring access ports in a wireless local area network, wherein a wireless switch controls the operation of one or more access ports and manages data communications with the one or more access ports, and wherein the access ports include one or more portals for communicating data to other devices. Software for operation of the access port is downloaded from the wireless switch. The access port sends data representing the identification of the one or more portals of the access port to the wireless switch. Data to configure the one or more portals of the access port is downloaded from the wireless switch to the access port.

In accordance with the invention there is provided an access port configured using the foregoing method.

In accordance with the invention there is provided an improved method for communicating in a wireless local area network, wherein a wireless switch controls the operation of one or more access ports and manages data communications with the access ports, and wherein at least one of the access ports includes an access port processor and a plurality of portals for communicating data to other devices. Separate network addresses corresponding to the access port processor and the portals are provided. Messages between the access port processor and the wireless switch are sent using a network address corresponding to the access port processor; and messages between the portals and the wireless switch are sent using network addresses assigned to the portals.

In a preferred embodiment sequence numbers are assigned to data messages between the access port and the wireless switch, wherein separate series of sequence numbers are assigned to each of the access port processor and the plurality of portals. The data messages may have an ethernet format, including a first ethernet header and a second header, wherein the ethernet header includes the network address and wherein the second header includes the sequence number. The second header may also include a message length field and/or a command field identifying message direction and message type. The second header may optionally include a code field indicating a command code for processing data in the message.

In accordance with the invention there is provided a wireless local area network arranged to operate using the method of the invention.

For a better understanding of the present invention, together with other and further objects, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of a wireless local area network in which the method of the invention may be practiced;

FIG. 2 is a block diagram showing an access port having a single portal in accordance with the prior art;

FIG. 3 is a block diagram of a first access port in accordance with the present invention;

FIG. 4 is a block diagram of a second access port in accordance with the present invention.

Throughout the figures, unless otherwise stated, the same reference numerals and characters are used to denote like features, elements, components, or portions of the illustrated embodiments.

DESCRIPTION OF THE INVENTION

As used in this specification the following terms have the following meanings:

• • An Access Port is a device with an Ethernet connection that contains at least one Portal.
  • A Portal is any device that is contained in an Access Port that provides a communication channel to some other device or network. A portal may be an IEEE 802.11 radio, a radio that uses some other technology than those described in IEEE 802.11 specifications, or a non-radio device such as a serial channel, fiber-optic link, etc. An access port may contain multiple portals for communicating using different protocols, such as different versions of IEEE 802.11.
  • A Wireless Switch is a device that controls one or more Access Ports and bridges data between these devices to a different network, typically a wired Ethernet network.
  • Adoption is the process by which an access port becomes associated with a wireless switch.
  • A message is a complete unit of data, as seen by the logic that is to process that data. Size restrictions on a particular network may force the “message” to be broken into multiple “packets” or “frames” for transmission on that network.
  • A packet or frame is a single unit of data as handled by a network. A data unit that is handled as a single entity on one type of network may have to be broken into multiple units for transmission on a different type of network. The term “packet” always refers to the unit of data as seen on the particular network involved.

Referring to FIG. 1 there is illustrated an example of a wireless local area network 10 as described in referenced co-pending application Ser. No. 09/528,697, wherein wireless switches 12, 13 (called cell controllers in the referenced application) communicate over an ethernet 14 with access ports 16, 18 and 20 (called RF Ports in the referenced application). The access ports 16, 18 and 20 are arranged to communicate with mobile units 22, 24 using a protocol such as one or more versions of IEEE Standard 802.11, or other wireless data communications protocol.

FIG. 2 illustrated an example of an access port 16 as described in the referenced co-pending application. The access port 16 includes a network interface card 26 (NIC), which includes ethernet controller 28 and digital signal processor 30 (DSP). A radio or RF Module 32 is provided having an antenna 34 for wireless communications with mobile units 22, 24. As described in the referenced application, lower level media access control (MAC) functions are performed in the DSP 30 while higher level MAC functions are performed in the wireless switch 12 or 13 with which the access port is communicating.

FIG. 3 illustrates an example of a first access port 18 in accordance with the present invention which includes two portals. Access port 18 includes a NIC 36 having an ethernet controller 38 and a processor 40. Processor 40 may be a digital signal processor or a microprocessor with associated memory and interfaces for communication with other devices. Access port 18 includes two portals 42, 46, which are designated Radio 1 and Radio 2. Each portal has an antenna 44, 48.

FIG. 4 illustrates an example of a second access port 20 in accordance with the present invention. Access port 20 is the same as access port 18, except that the second portal 50 is a fiber optic transducer instead of a radio and arranged to sent and receive serial data by fiber optic transmission line 48.

The present invention provides a protocol for communication between access ports 16, 18 and 20 and wireless switches 12, 13. The protocol includes two versions of some formats, a first version for communicating between a wireless switch 12, 13 and an access port 16 having a single portal. The second version of the protocol is for communicating between wireless switches 12, 13 and access ports 18, 20 having multiple portals. The two versions of the protocol format are compatibly used in the same system, and many of the formats for the two versions are identical.

The present invention further provides an arrangement for downloading runtime code from the wireless switches to the access ports. In the case of access ports having multiple portals, the present invention further provides an arrangement for configuring the portals of an access port.

In the case of multi-portal access ports, there are preferably multiple MAC addresses assigned to the access port. The first is the MAC address for the NIC card and the processor thereon. The remaining MAC addresses are preferably assigned to the portals of the access port. Generally, an operational access port will preferably have at least two MAC addresses, regardless of the number of portals.

All communication between the Wireless Switch and the Access Port processor or Portal within the Access Port uses WISP messages (WISP is an acronym for Wireless Switch Protocol). All fields are in big endian (network order) format. Within each field the highest order bit is shown to the left and the lowest order bit is shown to the right. The WISP message format is shown in Table 1.

TABLE 1
WISP Message Format.
Ethernet Header	WISP Header	Message Body	CRC
(14 bytes)	(6 bytes)	(variable length)	(4 bytes)

The Ethernet Header portion of the message is the standard IEEE 802.3 header, consisting of the destination MAC address, the source MAC address, and the Ethertype. The Ethertype field may contain the proprietary Symbol Ethertype value of 0x8783 or other value. The Ethernet header is shown in Table 2. The WISP Header is shown in Table 3.

TABLE 2
Ethernet Header.
	size in	Byte offset from
Field	bytes	start of message	description
destination	6	0	MAC address of destination.
source	6	6	MAC address of source.
ethertype	2	12	0x8783

TABLE 3
WISP Header.
	size in	byte offset from
Field	bytes	start of message	description
Command	2	14	command - direction, type,
			and code (see Table 4 for
			details)
Sequence	2	16	sequence number
Length	2	18	Message Body length (the
			number of bytes
			following this field)

The command field is divided into sub-fields as shown in Table 4 below.

TABLE 4
Command sub-fields.
	length in	bit
Field	bits	number	description
direction	1	15	Direction in which message
			is sent. See following
			paragraph.
type	3	14-12	Message type (message types
			are listed in Table 5).
code	12	11-0	Command code. Codes for types
			0, 1, 2, and 3 messages are
			listed in Tables 6 through 9,
			and are described in subsequent
			sections. The code for type 3
			messages is always 0. The
			diagnostic command type is
			defined in the diagnostics
			message body. Codes for type
			6 are TBD.

For messages that are sent to or from an Access Port, the direction sub-field is set to 0 if the message is sent from the Access Port and set to 1 if the message is sent to the Access Port. Type 3 messages are used for hardware diagnostics and may be specified by the device manufacturer.

The type sub-field values and meanings are listed in Table 5.

TABLE 5
Type sub-field values.
Type Description
0    Management message.
1    Wireless Data message.
2    Flow Control message.
3    Diagnostic message.
4    Reserved
5    Reserved
6    Inter-Wireless Switch message.
7    Reserved

The initial set of command codes for the management messages is set forth in Table 6. The initial set of command codes for the wireless data messages is set forth in Table 7. The initial set of command codes for the flow control messages is set forth in Table 8. The initial set of command codes for the diagnostic messages is set forth in Table 9.

TABLE 6
Type 0 message command code sub-field values.
	Direction	Command	Command Name	Usage
	1	0x0001	Configuration	Runtime
	1	0x0002	Reset	Runtime
	1	0x0003	UpdateTim	Runtime
		0x0004	undefined
	0	0x0005	Ack-old	Download
	0	0x0006	Status	Runtime
	1	0x0006	Heartbeat	Runtime
	0	0x0007	Hello	Download
	0	0x0008	ConfigMe	Runtime
	0	0x0009	LoadMe-old	Download
	0	0x000A	Nak-old	Download
	1	0x000B	LoadImage-old	Download
	1	0x000C	LoadDone-old	Download
	1	0x000D	Parent	Download
	0	0x000E	DeviceInfo	Runtime
	0/1	0x0015	Ack	Download/
				Runtime
	0	0x0019	LoadMe	Download
	0/1	0x001A	Nak	Download/
				Runtime
	1	0x001B	LoadImage	Download
	1	0x001C	LoadDone	Download
		all other	undefined
		values

TABLE 7
Type 1 command sub-field values.
Direction	Combined Value	Command	Meaning
0	0x1101 (from Access	0x0101	Frame body contains 1
	Port)		full packet
1	0x9101 (to Access	0x0101	Frame body contains 1
	Port)		full packet
0	0x1103 (from Access	0x0103	Frame body contains
	Port)		1st of 2 fragments of 1
			data frame
1	0x9103 (to Access	0x0103	Frame body contains
	Port)		1st of 2 fragments of 1
			data frame
0	0x1104 (from Access	0x0104	Frame body contains
	Port)		2nd of 2 fragments of 1
			data packet
1	0x9104 (to Access	0x0104	Frame body contains
	Port)		2nd of 2 fragments of 1
			data packet
		all other	undefined
		values

TABLE 8
Type 2 command sub-field values.
	Combined
Direction	Value	Command	Command Name
0	0x2010	0x0010	UpdateResults
0	0x2011	0x0011	DTIM_Poll
		all other values	undefined

TABLE 9
Type 3 command sub-field values.
Direction	Combined Value	Command	Meaning
0	0x3000 (from Access	0x3000	Diagnostics Response
	Port)		from Access Port to
			Diagnostics Host
1	0xB000 (to Access	0x3000	Diagnostics Command to
	Port)		Access Port from
			Diagnostics Host

The sequence field is used for multiple purposes. There are also multiple sequence number streams for use in different types of WISP messages. Each stream starts with a value of 0 and increments by one for each successive message.

The Wireless Switch assigns sequence numbers as follows: for a given Access Port, there is one 16-bit sequence number stream used for all Management messages sent by the Wireless Switch (the same stream is used regardless of whether the Management messages are addressed to the Access Port or one of the portals within the Access Port). In addition, there are different 16-bit sequence number streams used to send immediate Wireless Data messages to each portal within an Access Port. Immediate Wireless Data messages are those that are sent by the Wireless Switch to the portal without delay (this includes all directed data as well as those multicast data frames that match the multicast mask). Another sequence number “stream” is used by the Wireless Switch to send bulk-delayed Wireless Data messages to a portal. Bulk-delayed messages are those non-directed Data frames that are stored in the Wireless Switch until the portal requests them via a DTIM Poll message (i.e. all broadcasts plus those multicasts that don't match the multicast mask). Each time the Wireless Switch sends bulk-delayed messages, they start with sequence number 0 and increment by one until all queued messages are transmitted to the portal that requested them. In response to the next DTIM Poll, whether it comes from the same portal or a different one, the sequence numbers in the bulk-delayed Wireless Data messages start at 0 again.

The Access Port assigns sequence numbers as follows: the boot code utilizes a single 16-bit sequence number stream for all messages it transmits. After a successful download, the Access Port processor uses a different 16-bit sequence number stream for all messages it transmits (this currently only includes DeviceInfo messages). Each portal within the Access Port uses its own 16-bit sequence number stream for every message it transmits, regardless of whether they are Management, Wireless Data, or Flow Control messages.

An Access Port with two portals would deal with the following sequence number streams:

• • 3 transmitted
    • one for all messages sent by boot code
    • one for all messages sent by portal 1
    • one for all messages sent by portal 2
  • 4 received
    • one for all Management messages
    • one for immediate Wireless Data messages to portal 1
    • one for immediate Wireless Data messages to portal 2
    • one for bulk-delayed Wireless Data messages to either portal

During executable image downloading the sequence numbers provide a means of identifying each segment of the downloaded file by incrementing this value for each segment. This ensures that no frames are received out of sequence.

Sequence numbers are included in non-download management messages mainly to assist packet flow analysis and debug. Neither Wireless Switches nor portals are required to detect and/or reject non-download management messages that are received out of sequence.

During runtime the sequence numbers in immediate Wireless Data messages provide a means of flow control for 802.11 data frames sent from the Wireless Switch to a portal. The Wireless Switch and the portals use the Sequence field to reassemble any fragmented packets, as the sequence number will remain constant for each fragment of a Wireless Data message.

The following provides the details of Management message contents. Many of the messages follow a format that provides for the possibility of variable length fields. The general form of this format is:

Item ID

Item Length

Data

• Item IDs are unique single byte values.
• Item Lengths represent the size of the Data field in bytes. Item Lengths may be fixed or variable.
• Data is the actual data of interest.
• Management frames are frames with type=0.

During Access Port initialization, the Hello message is transmitted once per second until a Parent reply is received or upon the expiration of a predetermined period of time (e.g., 60 seconds). The Hello message format is shown in Table 10, and is used with the Parent message to provide a way for Wireless Switches to declare their intention to adopt an Access Port. The Hello message has no body.

TABLE 10
Hello message format.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	0xFFFFFFFFFFFF (Broadcast
			address)
Source	6	6	Access Port NIC MAC
			address
Ethertype	2	12	0x8783
Command	2	14	0x0007
Sequence	2	16	0-65535
Length	2	18	0

The Parent message is sent from a Wireless Switch to an Access Port in response to a Hello message. The Parent message is used with the Hello message to provide a way for Wireless Switches to declare their intention to adopt an Access Port.

A Wireless Switch sends a Parent message in response to a Hello message if the Wireless Switch is configured to do so. The format for the Parent message is shown in Tables 11 and 12, the message body consists of the Wireless Switch MAC address.

TABLE 11
Parent message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x800D
Sequence	2	16	0-65535
Length	2	18	6

TABLE 12
Parent message body.
		Byte offset from
	size in	start of message
Field	bytes	body	description
Parent	6	0	Wireless Switch MAC address
Address

In response to the Parent message, the Access Port sends a LoadMe message. The message content and format depends on the configuration of the Access Port. A first version of the LoadMe message, shown in Table 13 is utilized by the DSP-based Access Ports of the type described in co-pending application Ser. No. 09/528,697 and shown in FIG. 2. Other Access Ports, particularly access ports having more than one portal utilize the LoadMe message defined in Table 15.

The LoadMe message is sent by an Access Port to request that an executable image be downloaded into the Access Port. When an Access Port powers on, it sends LoadMe messages at 1-second intervals for 10 seconds, if there is no response the Access port must reset.

Information in the LoadMe message body is used by the Wireless Switch to determine whether or not to adopt the Access Port. Information in the LoadMe message may also be presented to the user at the Wireless Switch user interface, depending on the design of the Wireless Switch.

The LoadMe frame body is made up of a series of Items. Each Item consists of a 1-byte ID field, a 1-byte length field, and a variable length data field. The length field is the total length in bytes of the data field. The length field is always an even number. If the true length of a variable length data field is an odd number, then a one byte pad (zero) is added to the end of the data to make the length an even number.

Item IDs 1 through 5, described in Table 14 below, must always be present in the LoadMe frame. This message may be extended when appropriate and other Items may be included as needed. The receiver of the LoadMe message must ignore all Items that it does not understand.

TABLE 13
First version LoadMe message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	0xFFFFFFFFEFFF (Multicast
			address)
Source	6	6	Access Port NIC MAC
			address
Ethertype	2	12	0x8783
Command	2	14	0x0009
Sequence	2	16	0-65535
Length	2	18	Length of entire message
			(= 76)

TABLE 14
First version LoadMe message body.
		Byte offset from
	size in	start of message
Field	bytes	body	Description
Reserved	6	0	Unused
Frag Len	2	6	Length of all data
			to follow (= 48)
ID 0x01	2 + 6	8	Access Port NIC MAC
			address
ID 0x02	2 + 12	16	Access Port Serial
			number in binary or
			ascii
ID 0x03	2 + 2	30	Access Port PCB revision
			number in binary.
			First byte = major.
			Second byte = minor.
ID 0x04	2 + 2	34	Access Port Boot Loader
			revision number in
			binary. First byte =
			major. Second byte =
			minor.
ID 0x05	2 + 16	38	Access Port model number
			in ascii.

A second version of the LoadMe message, for use by advanced Access Ports, such as the multiple portal access ports shown in FIGS. 3 and 4, is shown in Tables 15 and 16.

TABLE 15
Second version LoadMe message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	0xFFFFFFFFFFFF (Broadcast
			address)
Source	6	6	Access Port NIC MAC
			address
Ethertype	2	12	0x8783
Command	2	14	0x0019
Sequence	2	16	0-65535
Length	2	18	Variable (see Table 16)

TABLE 16
Second version LoadMe message body.
		Length of data
	Item ID	field in bytes	Description
	0x01	6	Access Port NIC MAC address
	0x02	variable	Access Port Serial number in
			binary or ascii.
	0x03	2	Access Port PCB revision
			number in binary. First
			byte = major. Second
			byte = minor.

The Wireless Switch responds to the LoadMe message with a LoadImage message, which downloads the operating code for the network interface card (NIC) of the access port. For the first version of the LoadMe message the LoadImage message is described in Table 17 and 18.

The Wireless Switch sends the first LoadImage in response to a LoadMe (if the Wireless Switch determines that it will adopt this Access Port).

When the Access Port responds to the LoadImage with a Ack that indicates the next sequence number, the Wireless Switch sends the next LoadImage message. When the Access Port responds to the LoadImage with a Nak, the Wireless Switch resends the last LoadImage message.

This continues until the entire image has been downloaded.

The last portion of the file is sent in the body of a LoadDone message. This indicates to the Access Port that it has received its entire runtime image.

TABLE 17
First version LoadImage message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x800B
Sequence	2	16	0-65535
Length	2	18	Length of entire
			message (= 28 + R)

TABLE 18
First version LoadImage message body.
		Byte offset from
	size in	start of message
Field	bytes	body	description
Reserved	6	0	Unused
Frag Len	2	6	Length of all data
			to follow (= R)
Runtime	R	8	Block of runtime image
Image

In response to the second version of the Load Me message the Wireless switch sends the LoadImage message in the format specified in Tables 19 and 20. As with the first version, the image code may be sent in a number of fragments with the last fragment indicated to be a LoadDone message in the command code.

TABLE 19
LoadImage message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x801B
Sequence	2	16	0-65535
Length	2	18	R (see FIG. 20)

TABLE 20
LoadImage message body.
		Byte offset from
	size in	start of message
Field	bytes	body	description
Runtime	R	0	Block of runtime image
Image

Acknowledgement messages are sent by the access port in response to each LoadImage or LoadDone message from the wireless switch to the access port that is successfully received. The first version Ack message is responsive to the first versions of the LoadImage and LoadDone messages and is set forth in Tables 21 and 22. The second version responsive to the second version of the LoadImage and LoadDone messages is set forth in Tables 23 and 24. The sequence number in the Ack is taken from the sequence field of the LoadImage or LoadDone packet header.

TABLE 21
First version Ack message header (Ack
from Access Port to Wireless Switch).
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Access Port NIC
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x0005
Sequence	2	16	0-65535
Length	2	18	Length of entire
			message (= 30)

FIG. 22
Ack message body (Ack from Access Port to Wireless Switch).
		Byte offset from
	size in	start of message
Field	bytes	body	Description
Reserved	6	0	Unused
Frag Len	2	2	Length of all data
			to follow (= 2)
Download	2	8	Identical to the value
Sequence			of the Sequence field
Number			in the header of the
			received LoadImage or
			LoadDone message

TABLE 23
Second version Ack message header (Ack
from Access Port to Wireless Switch).
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Access Port NIC
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x0015
Sequence	2	16	0-65535
Length	2	18	2

TABLE 24
Second versionAck message body (Ack from
Access Port to Wireless Switch).
		Byte offset from
	size in	start of message
Field	bytes	body	description
Download	2	0	Identical to the
Sequence			value of the Sequence
Number			field in the header
			of the received
			LoadImage or LoadDone
			message

A Wireless Switch using the second version sends an Ack when a DeviceInfo packet is successfully processed. The sequence number in the Ack is taken from the sequence field of the DeviceInfo packet header. The format for the Ack message from the Wireless Switch to the Access Port is set forth in Tables 25 and 26.

TABLE 25
Ack message header (Ack from Wireless Switch to Access Port).
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x8015
Sequence	2	16	0-65535
Length	2	18	2

TABLE 26
Ack message body (Ack from Wireless Switch to Access Port).
		Byte offset from
	size in	start of message
Field	bytes	body	description
DeviceInfo	2	0	Identical to the
Sequence			value of the Sequence
Number			field in the header
			of the received
			DeviceInfo message

Nak messages are sent under the same conditions as Ack messages when a prior message is not successfully received. The first version Nak message format is set forth in Tables 27 and 28. The second version Nak messages from the Access Port to the Wireless Switch are set forth in Tables 29 and 30. The Nak messages from the Wireless switch to the Access Port are set forth in Tables 31 and 32. In connection with Nak messages the sequence number is taken as the last successful sequence field incremented by one.

TABLE 27
First version Nak message header (Nak
from Access Port to Wireless Switch).
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Access Port NIC
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x000A
Sequence	2	16	0-65535
Length	2	18	Length of entire
			message (= 30)

TABLE 28
First version Nak message body (Nak from
Access Port to Wireless Switch).
		Byte offset from
	size in	start of message
Field	bytes	body	description
Reserved	6	0	Unused
Frag Len	2	2	Length of all data
			to follow (= 2)
Download	2	8	Equal to the value
Sequence			of the Sequence field
Number			in the header of the
			received LoadImage
			or LoadDone message
			plus 1

TABLE 29
Second version Nak message header (Nak
from Access Port to Wireless Switch).
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Access Port NIC
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x001A
Sequence	2	16	0-65535
Length	2	18	2

TABLE 30
Second version Nak message body (Nak
from Access Port to Wireless Switch).
		Byte offset from
	size in	start of message
Field	bytes	body	description
Download	2	0	Equal to the value of
Sequence			the Sequence field
Number			in the header of the
			received LoadImage
			or LoadDone message
			plus 1

TABLE 31
Second version Nak message header (Nak
from Wireless Switch to Access Port).
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x801A
Sequence	2	16	0-65535
Length	2	18	2

TABLE 32
Second version Nak message body(Nak from
Wireless Switch to Access Port).
		Byte offset from
	size in	start of message
field	bytes	body	description
DeviceInfo	2	0	Equal to the value of
Sequence			the Sequence field
Number			in the header of the
			received DeviceInfo
			message plus one

A LoadDone message is sent by the Wireless Switch to the Access Port with the last fragment of code of the LoadImage message. In connection with Access Ports using the first version the LoadDone message is defined by Tables 33 and 34. The second version of the LoadDone message is shown in Tables 35 and 36. The LoadDone message contains the last segment of image code followed by a 16-bit checksum.

TABLE 33
First version LoadDone message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x800C
Sequence	2	16	0-65535
Length	2	18	Length of entire
			message (= 30 + R)

TABLE 34
First version LoadDone message body. The
number of bytes remaining may be zero.
		Byte offset from
	size in	start of message
field	bytes	body	description
Reserved	6	0	Unused
Frag Len	2	2	Length of all data
			to follow (= 2)
Runtime	R	8	Last block of
Image			runtime image.
Checksum	2	R	16-bit, ‘exclusive or’
			checksum of the entire
			downloaded image file.
			Big endian. If the
			total number of bytes
			in the image is odd,
			a zero ‘pad’ byte is
			added to perform the
			checksum calculation.

TABLE 35
Second version LoadDone message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x801C
Sequence	2	16	0-65535
Length	2	18	R + 2 (see
			FIG. 3.12a)

TABLE 36
Second version LoadDone message body. The
number of bytes remaining may be zero.
		Byte offset from
	size in	start of message
field	bytes	body	description
Runtime	R	0	Last block of runtime
Image			image.
Checksum	2	R	16-bit, ‘exclusive or’
			checksum of the entire
			downloaded image file.
			Big endian. If the
			total number of bytes
			in the image is odd,
			a zero ‘pad’ byte is
			added to perform the
			checksum calculation.

An Access Port using the second version sends a DeviceInfo packet to report the combined capabilities of all its portals to the Wireless Switch. The DeviceInfo message is sent when the Access Port's runtime image is loaded and is executing correctly, but before its radios have been configured. The DeviceInfo message is broadcast so that all Wireless Switches may be aware of the Access Port's radio configuration.

If the Access Port received a Parent response from its Hello message, the Access Port expects an Ack of the DeviceInfo message from its Parent Wireless switch (i.e. from the MAC address indicated by the first Parent to reply to the Access Port's Hello message). If the Access Port does not see such an ACK within 10 seconds, it will reset and begin sending Hello messages.

If the Access Port did not receive a Parent response from its Hello message, the Access Port will send five DeviceInfo messages (once per second). It will then reset and begin sending Hello messages.

The Body of the DeviceInfo message is made up of a series of items. These items are not guaranteed to be in any particular order, although it is suggested that they be placed in numerical order according to the value of their ID fields.

The format for the DeviceInfo message is set forth in Tables 37 through 40.

TABLE 37
DeviceInfo message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	0xFFFFFFFFFFFF
			(Broadcast address)
Source	6	6	Access Port NIC
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x000E
Sequence	2	16	0-65535
Length	2	18	Variable (see
			FIG. 38)

TABLE 38
DeviceInfo Message Body.
		length of data
	item ID	field in bytes	Description
	0x01	6	Access Port NIC MAC address.
	0x02	variable	Access Port serial number
			in ascii.
	0x03	2	Access Port PCB revision
			number in binary. First
			byte = major. Second
			byte = minor.
	0x05	variable	Access Port model number
			in ascii.
	0x06	Variable	WISP version in ascii
	0x07	6	Parent. The MAC address of
			the first Wireless Switch
			to respond to the Access
			Port's Hello frame. All 0's
			if no Wireless Switch replied
			to the Hello frame.
	0x08	Variable	Access Port runtime firmware
			version number in
			ascii.
	0x09	2	Number of installed portals
			(radios).
	0x0A	2	Portal index (0 based).
	0x0B	2	Portal type (see FIG. 3.13b).
	0x0C	variable	Portal firmware revision
			number in ascii.
	0x0D	2	Options bit mask (see
			FIG. 3.13c).
	0x0E	6	Portal MAC address
	0x58	1	Number of supported ESSs

Items Oxa, Oxb, Oxc, Oxd, and Oxe above may preferably be repeated (in order) for each portal on the device.

TABLE 39
Portal Type Codes.
Portal Type description
0           IEEE 802.11a radio.
1           IEEE 802.11b DS radio.
2           IEEE 802.11g radio.
3           IEEE 802.11b FH radio.

TABLE 40
Option Bit Mask Definitions.
Bit number description
15         Internal primary antenna installed.
14         External primary antenna installed.
13         Internal secondary antenna installed.
12         External secondary antenna installed.

It is notable that the bits of Table 40 may have meaning only if the Access Port has the capability to detect the presence of the antenna. Thus, the Wireless Switch must preferably be aware of the Access Port's capability to detect antennas.

When the Access Port's runtime image is loaded following the second version of the protocol and the Access Port has successfully sent a DeviceInfo to the Wireless Switch, but the radio has not been configured, each portal of the Access Port sends the ConfigMe packet to report its capabilities to the Wireless Switch and to request its configuration. Until a radio has been configured, it sends a ConfigMe packet every 3 seconds for 9 seconds. After which it sends out a ConfigMe every 60 seconds until a response if received. When the Configuration Packet has been successfully received and processed by the radio, the ConfigMe is no longer sent. The radio then begins normal operation. The format of the ConfigMe message is set forth in Tables 41 and 42.

TABLE 41
ConfigMe message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Radio MAC address
Ethertype	2	12	0x8783
Command	2	14	0x0008
Sequence	2	16	0-65535
Length	2	18	Variable (see
			Table 42)

TABLE 42
ConfigMe message body.
		length of data
	item ID	field in bytes	Description
	0x01	6	Access Port NIC MAC address.
	0x07	6	Parent. The MAC address of
			the first Wireless Switch
			to respond to the Access
			Port's Hello frame.
	0x0A	2	Portal index (0 based).
	0x0B	2	Portal type (see Table 39).
	0x0C	variable	Portal firmware revision
			number in ascii.
	0x0D	2	Options bit mask (see
			Table 40).
	0x0E	6	Portal MAC address.
	0x0F	2	Total number of buffers
			available to hold packets
			awaiting forwarding
			(transmission, if the
			Portal is a radio).
	0x10	2	Transmit buffer size
			in bytes
	0x11	1	Hop Set (FH port value)
	0x12	1	Hop Sequence (FH port
			current value)
	0x13	2	Hop dwell Time (FH port
			current value

It is noted that the FH portal will preferably send out certain parameters already stored in FLASH configuration memory. Exemplary values are set forth in Table 42 and are Hop Set (values may be 1-3), Hop sequence (values may be 1-max number of channels/3), and hop dwell time (range 20-1000 in K-usec units).

The Wireless Switch may send a Configuration packet in response to the ConfigMe packet or whenever a change in configuration is required.

The Configuration message includes a header shown in Table 43 and is made up of a variable number of Items. The format of the possible Configuration Items is described in Tables 44 to 51. A Portal must ignore any configuration item that it does not recognize.

Configuration messages will generate a Status message if they are processed correctly. If the Access Port determines that the Configuration is erroneous, the Access Port shall reply to the Configuration with a Status message that indicates the error in the Configuration Error Type field.

TABLE 43
Configuration message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Radio MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x8001
Sequence	2	16	0-65535
Length	2	18	Variable (see
			Table 44)

TABLE 44
Configuration Message Body Item Descriptions.
		Length of data
	Item ID	field in bytes	description
	0x20	2	Configuration sequence number.
			Incremented for each
			succeeding Configuration
			messages sent to a particular
			radio.
	0x21	variable	ESS ID. First byte is ESS
			index, followed by ESS ID
			in ascii.
	0x22	1	Index of ESS to use in beacons.
	0x23	2	ESS ID activation mask. Bit 0 =
			ESS 0, etc. If the bit is set,
			that ESS is active, otherwise
			it is not active. When an
			Access Port receives a Probe
			for an active ESS, the Access
			Port will generate a Probe
			Response. When an Access Port
			receives a Probe for an
			inactive ESS, the Access Port
			will not generate a Probe
			Response.
	0x24	1	Transmit power level. Units
			in dbm.
	0x25	1	Primary channel number.
			IEEE 802.11b channels are 1
			through 14.
			IEEE 802.11a channels are 36,
			40, 44, 48, 52, 56, 60, 64,
			149, 153, 157, 161.
	0x27	2	Allowed rates mask. (See Table
			67 for rate mapping.)
	0x28	2	Basic rates mask. (See Table
			67 for rate mapping.)
			NOTE: For the Atheros 11a
			radio there are only two
			possibilities for Basic
			Rates: 6 and {6, 12, 24). For
			the FH radio possibilities for
			Basic Rates are 1 only, 2
			only, or 1 & 2.
	0x29	1	CCA level.
	0x2A	1	CCA mode (algorithm 1, 2, 3,
			or 4).
	0x2B	2	RTS threshold (0-2437). A zero
			value causes an RTS frame to
			precede every MSDU.
	0x2C	2	ESS Options. First byte is ESS
			index. Second byte is a
			capability mask. See FIG.
			3.15b.
	0x2D	2	Broadcast ESS enable mask. Bit
			0 = ESS 0, etc. If a bit for a
			specific ESS is set, the radio
			will respond to probes using a
			broadcast ESS with a probe
			response.
	0x2E	2	Option mask. See Table 45 for
			option definitions.
	0x2F	variable	Allowed channels (one byte
			each). This is the list of
			channels that will be scanned
			during an Auto Channel Scan
			procedure. Channels in this
			list will be binary numbers
			as listed below. The selected
			channel will be returned to
			the Wireless Switch in a
			Status message.
			IEEE 802.11b channels are 1
			through 14.
			IEEE 802.11a channels are 36,
			40, 44, 48, 52, 56, 60, 64,
			149, 153, 157, 161.
	0x30	1	Time (in seconds) to scan any
			channel for the presence of
			radar before using.
	0x31	2	Time (in TU or kilo micro-
			seconds) of quiet period if
			Bluetooth coexistence is
			enabled.
	0x32	1	Time (in 64 microsecond
			pieces) of guard band if
			Bluetooth coexistence is
			enabled.
	0x33	2	Beacon interval in TU (kilo
			microseconds).
	0x34	1	DTIM interval, measured in
			beacon intervals.
	0x35	variable	Reserved for IEEE 802.11i
			security element.
	0x36	variable	Country information element.
			See Tables 47 and 48
	0x37	17	Load balance element. See
			Table 49.
	0x38	variable	WiFi Protected Access (WPA)
			Element. First byte is
			ESS index. Following bytes are
			WPA security element. See
			Table 50.
	0x39	1	Hop Algorithm (0 - IEEE,
			1 - Hop Delta)
	0x42	1	Hop Set (1, 2, or 3)
	0x43	1	Hop Sequence (index into hop
			table possible values are 1
			through max # of channels/3)
	0x44	2	Hop Dwell Time (Kilo
			microseconds)
	0x45	Variable	Hop channel table

Note: For the FH port the Country information element could be used to set up First channel and Max Channel for the Hop Table. Therefore First Hop Channel and Maximum number of channels where not inserted to Configuration message body.

TABLE 45
ESS Options Item Bit Definitions.
bytes description
1     ESS index (0-3).
1     Bit mask. Bit 0 = WEP enabled.

TABLE 46
Option Mask Bit Definitions.
bit description
0   Secure beacon - if set, the ESS is not
    transmitted in the beacon.
1   Automatic channel scan - enabled if bit
    is set.
2   Short preamble - enabled if bit is set.
3   Rogue AP detection - enabled if bit is
    set.
4-7 Antenna diversity settings. See Table 51
    for definitions
8   Scan channels for radar before using.

TABLE 47
Country Information Element header.
field	bytes	description
m_byElementId	1	ELEMENT_ID_COUNTRY_INFO = 7
m_byLength	1	Variable - see below.
m_CountryCode	2	Country ID padded with
		trailing spaces
m_indoor_outdoor	1	Indoor vs Outdoor setting

TABLE 48
Country Information Element channel descriptor.
	field	bytes	description
	m_byMinChannel	1	first channel for country
	m_byMaxChannel	1	number of channels
	m_byMisc	1	maximum tx power in dBm
			(signed)
	Note that the number of the above channel descriptors is variable for each country (for each Country Information Element header). Each country has as many of the above three-byte channel descriptors as there are non-contiguous bands - or have different power levels within a contiguous group of channels. For 802.11a, contiguous means “monotonically increasing”. Thus, for example, the entire U-NII lower band (with a maximum of 10 dBm power) could be specified as:
	m_byMinChannel = 36
	m_byMaxChannel = 4
	m_byMisc = 10
	The above values for the channel descriptor would indicate that channels 36, 40, 44, and 48 are allowed.
	For 802.11a all channels monotonically increase by four. For 802.11b all channels monotonically increase by one.

TABLE 49
Load Balance Element.
field	bytes	description
m_byElementId	1	ELEMENT_ID_LOAD_INFO = 173
m_byLength	1	length is fixed at 15
m_byOUI	3	0x00a0f8 (Symbol)
m_woAssociatedMUs	2	total associated MUs
m_woKBPS	2	kilo bytes per second
m_woPacketsPS	2	packets per second
m_woTXPower	2	transmit power
m_dwNetTime	4	network time

TABLE 50
WiFi Protected Access (WPA) Element.
	field	bytes	description
	ESS index.	2	Index of ESS being
			referred to.
	ID	1	221 decimal or 0xDD
	length	1	variable
	OUI	3	0x00, 0x50, 0xF2
	OUI Type	1	0x01
	version	2	TBD
	MC Suite	4	Multicast suite
			selector. (For
			selector details,
			see SSN documentation.)
	UC Suite count	2	Number of unicast
			suite selectors.
	UC Suite list	4*N	Unicast suite selectors.
	Auth Suite count.	2	Number of authentication
			suites.
	Auth Suite list	4*N	Authentication suite
			selectors.

TABLE 51
Antenna Diversity Settings.
bit description
4   Receive on Primary Antenna
5   Receive on Secondary Antenna.
6   Transmit on Primary Antenna
7   Transmit on Secondary Antenna

The configuration sequence number is incremented by the Radio when all configuration processing is complete. The radio sends this value to the Wireless Switch in a Status packet to indicate that all changes specified have been successfully made. If the radio receives a Configuration packet with the previously seen sequence number the radio will ignore that packet.

The initial Configuration packet sent to a radio must contain all of the configuration information that is required for radio operation. If a field is absent, the radio will use a default value. Subsequent Configuration packets must contain Items that are to be changed, but may contain Items that have not changed.

Every 5 seconds, a configured Radio sends a Status message to the Wireless Switch to announce that it is still operational. Additional Status packets can be sent at any time as needed so that the Wireless Switch may recognize significant changes. Examples of significant changes are the auto channel scan feature completes, an 802.11a portal detects radar on its current channel, or an erroneous Configuration message is received as indicated by the Configuration Error Type field. When this occurs, the Configuration message that contained the error, is not effective.

The Status packet is also used to send statistical and status information to the Wireless Switch. These Items can be defined in the future.

The body of this message consists of a series of Items. Each Item consists of a 1-byte Item ID, a 1-byte length, and a variable length data field. The length field is the total length in bytes of the data field. The Status message format is shown in Tables 52, 53 and 54.

TABLE 52
Status message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Radio MAC address
Ethertype	2	12	0x8783
Command	2	14	0x0006
Sequence	2	16	0-65535
Length	2	18	Variable (see
			Table 53)

TABLE 53
Status Message Body.
item ID	bytes	meaning	description
0x50	2	Auto channel	0xFFFF => ACS in process
		scan.	0xFFFE => ACS complete;
			new configuration pending.
			Else => Current channel
0x51	2	Configuration	Configuration sequence
		complete.	number of active configuration
0x52	4	Cumulative	Number of CRC errors since
		CRC Errors	last reset (if available)
0x53	1	Radar Detect	The existence of this
			field means that radar
			was detected.
			The one-byte data field
			indicates the channel on
			which the radar was detected.
0x54	2	Configuration	0 means no errors. Non
		Error Type	zero indicates an error
			number. See Table 54 for
			a list of error numbers.
0x59	1	Seconds since	The number of seconds
		last heartbeat	since the last heartbeat
			message was received by
			the Access Port

During normal operation, the selected channel item is the channel currently in use by the radio. The value 0xffff indicates that Auto Channel Scan is in progress. The value 0xfffe indicates that Auto Channel Scan has completed and the radio is waiting for a new configuration.

TABLE 54
Error numbers.
error number meaning
0x01         ACS bit set. No channels indicated.
0x02         Channels inconsistent with Country
             Information Element

The Wireless Switch sends a Heartbeat message to each Radio each second to indicate to the Radio that the Wireless Switch is still operational, to keep the network time synchronized and to update load balance data

This load balance data becomes part of the Load Balance Element in the beacon and probe response RF packet. The requirement for the 1-second update time is to keep the network time synchronized. The Heartbeat message format is shown in Tables 55 and 56.

TABLE 55
Heartbeat message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Radio MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x8006
Sequence	2	16	0-65535
Length	2	18	19

TABLE 56
Heartbeat Message Body.
	item ID	bytes	description
	0x37	17	Load balance element. See Table 49.

The purpose of UpdateTIM packet is to update the Partial Virtual Bitmap field of the beacon for a Radio and to update the bitmap offset of the bitmap control field. The rest of the fields in TIM element are filled in by the Radio.

The TIM map is compiled by the Wireless Switch based on the traffic currently stored for each PSP MU that is associated through this radio (if any). The length field of the fragment control header indicates the total length of the element.

Format for the UpdateTIM message is shown in Tables 57 and 58. The first byte of the body in the packet will indicate the bitmap offset for bitmap control. The rest is the Partial Virtual Bitmap to be part of each beacon.

TABLE 57
UpdateTIM message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Radio MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x8003
Sequence	2	16	0-65535
Length	2	18	Variable (see
			Table 58)

TABLE 58
UpdateTIM Message Body.
		Byte offset from
	size in	start of message
field	bytes	body	description
BSS Index	2	0	Index of BSSID that
			is requesting its bulk-
			delayed Wireless Data
			messages. Valid range =
			0-3 (4 BSSIDs supported)
Bitmap	1	2	Bitmap offset to be
Offset			included in the TIM
			information element,
			as defined by 802.11
Partial	variable	3	Partial virtual bitmap
Virtual			to be included in the
Bitmap			TIM information element,
			as defined by 802.11

The purpose of Reset packet is to reset the Access Port. It may be directed to either the Access Port NIC MAC address or to a Portal MAC address. When directed to the Access Port NIC MAC address, the Reset packet has the same effect as toggling power at the Access Port—the Access Port will revert back to its initialization procedure.

When directed to a Portal MAC address, the Portal will revert to the ConfigMe stage, sending ConfigMe messages until a Configuration is received from the Portal's Parent Wireless Switch. Portals other the destination portal shall not change their operating state. The header for the Reset message is shown in Table 59. This message has no body.

TABLE 59
Reset message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Access Port NIC
			MAC address OR
			Portal MAC
			address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x8002
Sequence	2	16	0-65535
Length	2	18	0

In the following discussion the term “radio” is used to refer to a Portal (radio or other entity) that resides within an Access Port, even in the case where the Access Port only consists of one radio and the same MAC address is used for both Access Port and radio.

Each message to be sent to a radio by a Wireless Switch is sent encapsulated in one or more Wireless Data Packets. Each time the Wireless Switch creates a Wireless Data Packet—without fragments—in which to encapsulate a message, it increments the value of the sequence field in that Wireless Data Packet by 1. If the message must be fragmented, the sequence number is the same value for each fragment of the message. The radio remembers the value of the sequence field in the last of the Wireless Data Packets that contained each frame to be transmitted. The sequence numbering is independent for each radio within an Access Port. As soon as possible after the radio forwards a frame that it received from a Wireless Switch, it reports the value of the sequence field that was in the Wireless Data Packet that originally contained that frame back to the Wireless Switch in the Results1 or Results2 fields as described below.

There are two methods that a radio can use to report to the Wireless Switch the sequence fields of frames most recently forwarded. Both methods involve filling in the Tx Results fields of a message that is sent to the Wireless Switch. The first method is to fill in the Tx Results1 and Tx Results2 fields in a Wireless Data Packet that contains a message received by the radio and destined for the Wireless Switch. The second method is to create an UpdateResults message, fill in one or more Tx Results fields as necessary, and send it to the Wireless Switch. The only purpose of this message is to report the results fields to the Wireless Switch. Each radio must implement a mechanism to report the results of forwarded messages to the Wireless Switch as quickly as possible.

When a fragmented message received by the Access Port from the Wireless Switch has been successfully transmitted by the Access Port, the successful result is indicated as described above. In this case, just one Results indication is sent from the Access Port to the Wireless switch—even though the Access Port received two frames (two fragments) for the message.

The format for a wireless data message from the access port to the wireless switch is set forth in Table 60 and 61. When the access port is configured using the first version of the protocol and having only one access port, the Radio MAC address is the address of the Access Port NIC.

TABLE 60
Wireless Data message header (Data
from Radio to Wireless Switch)
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Radio MAC address
Ethertype	2	12	0x8783
Command	2	14	0x1101 (if frame
			body contains a
			complete packet)
			0x1103 (if frame
			body contains 1st
			of 2 fragments)
			0x1104 (if frame
			body contains 2nd
			of 2 fragments)
Sequence	2	16	0-65535
			NOTE: The Sequence
			value shall be
			constant for a
			given pair of
			Wireless Data
			messages of Command
			types 0x1103 and
			0x1104 (i.e.
			fragments share a
			single sequence
			number)
Length	2	18	D + 14 (see
			Table 61)

TABLE 61
Wireless Data message body (Data
from portal to Wireless Switch)
		Byte offset from
	size in	start of message
field	bytes	body	Description
Flow	2	0	Future sequence number
Control			corresponding to
Window			the last immediate
			Wireless Data message
			that can be received,
			given the currently
			available buffers in
			the portal
Tx Results 1	4	2	Allows results of a
			completed frame
			transmission to be
			piggybacked onto a
			received frame (see
			Table 62 for details)
Tx Results 2	4	6	Allows results of a
			2nd completed frame
			transmission to be
			piggybacked onto a
			received frame (see
			Table 62 for details)
Rx Data	2	10	Information about the
			received frame (see
			Table 63 for details)
Channel	2	12	Channel on which the
			data frame was
			received (see Table
			65 for details)
Data Frame	D	14	802.11 data frame
			received by the portal

The format for the TxResults 1 and TxResults 2 fields is set forth in Table 62.

FIG. 62 Format of the Tx Results1 and Tx Results2 fields
		length
	field	(bits)	bit #	Description
	ok	2	31-30	0 = tx results invalid
				1 = frame sent successfully
				2 = frame failed: excessive
				retries
				3 = frame failed: lost
	rate	5	29-25	data rate at which packet was
				transmitted (rates specified
				in Table 64)
	retries	5	24-20	total number of retries for
				transmitted packet
	channel	8	19-12	Channel on which
				frame was transmitted
	seq	12	11-0	transmission sequence number
				modulo 4096
				NOTE 1: although the
				corresponding sequence field
				in the WISP header is 16 bits,
				only the lower 12 bits are
				supplied in this field since
				this is adequate for the
				Wireless Switch to uniquely
				identify the results.

When the radio has received a message that is to be forwarded to the Wireless Switch, it fills in the TxResults1 and TxResults2 fields of the frames that contain the encapsulated message as follows, depending on what has or has not already been reported to the Wireless Switch:

If all data sent by the Wireless Switch to the radio to be forwarded has been forwarded and the results have been reported to the Wireless Switch, both fields are set to zero.

If only 1 message sent from the Wireless Switch has been forwarded and not reported, the TxResults1 field is filled in with information regarding the last (or only) fragment of that message and TxResults2 is set to 0.

If more than 1 message sent from the Wireless Switch has been forwarded and not reported, the TxResults1 is filled in with information regarding of the oldest unreported message and the TxResults2 field is filled in with information regarding of the next oldest unreported message.

A portal can report lost frames by setting the “ok” subfield equal to 3, the “seq” subfield to the sequence number that was lost, and setting the rest of the subfields to 0.

If the Access Port has forwarding results ready to report, but there are no received frames waiting to be sent to the Wireless Switch, the radio will create and send UpdateResults messages to the Wireless Switch soon after the transmit results are known to the Access Port. The TxResults1 and TxResults2 fields are filled in as described above. How long a portal hangs on to unreported results before creating and sending an UpdateResults message is implementation dependent, but in general this time should be minimized.

The results reported to the Wireless Switch may not be in sequence. Each radio is free to transmit Data frames in whatever order it deems most efficient, but transmit results must be sent back to the Wireless Switch in the same order as the results become known to the radio.

The Rx Data field is filled in the body of the Wireless Data Packet that contains the last fragment of that message using the format of Table 63. The RSSI sub-field contains the relative signal strength with which the message was received (if the Portal is a radio), as reported by the supporting hardware. The rate sub-field contains the encoded data rate of the received message (if the Portal is a radio). Encoding of the data rate is shown in Table 64 below. The format for the channel field is shown in Table 65.

TABLE 63
Format of the Rx Data field.
		length
	field	(bits)	bit #	description
	RSSI	8	15-8	receive signal strength
				indicator
		3	7-5	Not used
	rate	5	4-0	receive data rate (see
				Table 64)

TABLE 64
data rate values.
value rate (MBPS)
0     1
1     2
2     5.5
3     6
4     9
5     11
6     12
7     18
8     22
9     24
10    36
11    48
12    54

TABLE 65
Format of the channel field.
		length
	Field	(bits)	bit #	description
	channel	8	7-0	Channel this frame
				was received on
	Reserved	8	15-8	Not used

The format for the header field and body of a data message from the wireless switch to a radio is shown in Table 66 and 67.

TABLE 66
Wireless Data message header (Data
from Wireless Switch to portal)
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Radio MAC address
Source	6	6	Wireless Switch
			MAC address
Ethertype	2	12	0x8783
Command	2	14	0x9101 (if frame
			body contains a
			complete packet)
			0x9103 (if frame
			body contains 1st
			of 2 fragments)
			0x9104 (if frame
			body contains 2nd
			of 2 fragments)
Sequence	2	16	0-65535
			NOTE: The Sequence
			value shall be
			constant for a
			given pair of
			Wireless Data
			messages of Command
			types 0x9103 and
			0x9104 (i.e. fragments
			share a single
			sequence number)
Length	2	18	D + 14 (see Table 67)

TABLE 67
Wireless Data message body (Data
from Wireless Switch to portal)
		Byte offset from
	size in	start of message
field	bytes	body	description
Start Rate	2	0	Initial transmission
			rate to attempt,
			encoded as described
			in Table 4.5.
Allowed	4	2	Bit map of allowed
Rates			transmission rates
			(see Table 68)
Transmit	2	6	Information about
Control			the frame to be
			transmitted (see
			Table 69 for details).
Reserved	6	8	Reserved for future
			growth.
			NOTE: The number of
			bytes in any
			Wireless Data message
			type, prior to the
			actual data frame,
			is consistent regardless
			of the message direction.
Data Frame	D	14	802.11 data frame to be
			transmitted by the
			portal

The bit map values for any transmit rate, including the Allowed Rates field in Table 67, is shown below in Table 68. The top row is the bit number. The bottom row is the data rate in megabits per second.

TABLE 68
Rate bit map.
15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
			54	48	36	24	22	18	12	11	9	6	5.5	2	1

The Transmit Control field is set forth in Table 69. The priority field is intended to allow flexibility in support of Quality of Service mechanisms. Where such mechanisms are not in place the field is set to zero.

The group field specifies the priority group to which this message belongs.

The relationship between Priority Group and Priority is as follows: Each priority group may be sub-divided into up to 16 priorities. Any message in one priority group has priority over any message in a lower-numbered priority group, regardless of the value of their respective priority fields.

The profile field specifies a retry algorithm. More specifically, the RF Port uses this value to determine the following information for each transmission:

• • Maximum contention window (CW) for each transmission attempt
  • Maximum number of retries to be attempted
  • When to lower the Tx rate

The retry algorithm to be used is not specified by the protocol. Instead, it is up to the implementation to define the appropriate transmit profile for each of the five profile types.

TABLE 69
Transmit Control field.
	Length
field	(bits)	bit #	description
priority	8	15-8	0
group	4	7-4	priority groups:
			0 = normal (lowest priority group)
			1 = DTIM/BCMC
			2 = management/voice (highest priority
			group)
profile	4	3-0	tx profile:
			0 = BC/MC
			1 = Data
			2 = Voice Data
			3 = Voice MC
			4 = Management Frame

Flow control allows for the efficient movement of data from a Wireless Switch to a portal. It also ensures that data will not be sent to a portal that doesn't have room for it. There are two distinct types of data that flow control applies to: immediate and bulk-delayed. Each type is handled with a different method of flow control.

Immediate Wireless Data messages are flow-controlled via the Sequence fields in their headers, and the Flow Control Window field in the bodies of upstream (i.e. from portal to Wireless Switch) Wireless Data, UpdateResults, and DTIMPoll messages. The Flow Control Window field allows a portal to advertise to the Wireless Switch how much room it has left to accept additional Wireless Data messages. This room is expressed in terms of a “window” of sequence numbers, where the Flow Control Window value is the last sequence number that can be accepted. As a portal transmits data via RF, it frees up additional buffer space and subsequently advertises a new window in the next Wireless Data, UpdateResults, or DTIMPoll message it transmits. The advertised window will always be either equal to or larger than the last advertised window (excluding the 16-bit wraparound case).

Bulk-delayed Wireless Data messages are flow-controlled via the DTIMPoll message. This message is sent prior to an imminent DTIM time, and signals the Wireless Switch to send all buffered non-directed data to the portal that requested it, up to the limit specified within the DTIMPoll message. The sequence numbering for bulk-delayed Wireless Data messages is separate from immediate Wireless Data messages, and each portal must maintain a separate memory area for each data type. Receipt of (and subsequent RF transmission of) bulk-delayed Wireless Data messages have NO impact on the value of the Flow Control Window field.

The UpdateResults message is sent to the Wireless Switch by a Radio when information is available regarding the status of one or more completed data forward (transmit) operation(s) and no data that has been received is pending to be sent to the Wireless Switch. The Tx Results fields are filled in as described above. The TxResults 1 and TxResults 2 fields are always included in this message, even if there is only one result to report (in that case, the Tx Results2 field would be invalid). Additional TxResults can be appended to this message as necessary.

This message also serves to update the Wireless Switch with the latest flow control information. The format for the UpdateResults message is set forth in Tables 70 and 71.

FIG. 70 UpdateResults message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Radio MAC address
Ethertype	2	12	0x8783
Command	2	14	0x2010
Sequence	2	16	0-65535
Length	2	18	2 + (N * 4), where
			N is the number
			of Tx Results
			included in the
			body of this
			message

FIG. 71 UpdateResults message body.
		Byte offset from
	size in	start of message
Field	bytes	body	Description
Flow	2	0	Future sequence number
Control			corresponding to the
Window			last immediate Wireless
			Data message that can
			be received, given the
			currently available
			buffers in the portal
Tx	4	2	Allows results of a
Results 1			completed frame
			transmission to be
			reported (see Table 62
			for details)
Tx	4	6	Allows results of a 2nd
Results 2			completed frame
			transmission to be
			reported (see Table 62
			for details)
Reserved	4	10	Unused
Number	2	14	Number of additional
of Results			Tx Results fields
			included in this message
			(doesn't include the
			two Tx Results fields
			above: they are always
			present).
			Valid range: 0-100
Tx	4	16	Results for first
Results_1			extra unreported
			frame (see Table
			62 for details)
Tx	4	16 + 4*(N − 1)	Results for Nth
Results_N			extra unreported
			frame (see Table
			62 for details).
			NOTE: The maximum
			value of N is 100.

The radio sends theDTIM_Poll message to the Wireless Switch to request that any stored (buffered) broadcast or multicast messages be sent. The amount of time between the DTIM_Poll and DTIM time is implementation dependant. When the DTIM time occurs, the radio will transmit any broadcast or multicast messages that it has received since the last DTIM.

This message also serves to update the Wireless Switch with the number of currently available transmit buffers (non-DSP) for this radio.

This message can be used to send any previously unreported TxResults to the Wireless Switch. Zero, one, or two valid TxResults may be included, but the TxResults 1 and TxResults 2 field are always present even if they don't contain valid data. The format for the DTIM_POLL message is set forth in Tables 72 and 73.

TABLE 72
DTIM_Poll message header.
	size in	Byte offset from
Field	bytes	start of message	description
Destination	6	0	Wireless Switch
			MAC address
Source	6	6	Radio MAC address
Ethertype	2	12	0x8783
Command	2	14	0x2011
Sequence	2	16	0-65535
Length	2	18	8

TABLE 73
DTIM_Poll Message Body.
		Byte offset from
	size in	start of message
Field	bytes	body	description
Flow	2	0	Future sequence number
Control			corresponding to the
Window			last immediate Wireless
			Data message that can
			be received, given the
			currently available
			buffers in the portal
Tx	4	2	Allows results of a
Results 1			completed frame
			transmission to
			be reported (see FIG.
			4.2 for details)
Tx	4	6	Allows results of a 2nd
Results 2			completed frame transmission
			to be reported (see FIG.
			4.2 for details)
Reserved	4	10	Unused
Last	2	14	Value of the Sequence field
Sequence			in the header of the
			last received immediate
			Wireless Data message
Portal	2	16	Old or New.
Type			0 => old
			(DSP based)
			1 => new
Capacity	2	18	Bulk-delayed Wireless Data
			message transmit capacity.
			If the portal type field
			above is 0, then this
			value is in bytes. If
			the portal type field
			above is 1, then this
			value is in buffers.
BSS	2	20	Index of BSSID that is
Index			requesting its bulk-
			delayed Wireless Data
			messages.
			Valid range =
			0-3 (4 BSSIDs
			supported)

The process by which an Access Port becomes associated with (or adopted by) a Wireless Switch is called the Access Port Adoption Process (APAP). Some WISP messages are used only during this Adoption Process.

The following illustrates the possible normal initialization message sequences between a Wireless Switch and an Access Port.

The first section describes a normal successful download between the Wireless Switch and a multi-portal access port. The second section describes the message exchanges between a multi-portal access port and the Wireless Switch when no Wireless Switches are configured to adopt the port. The third section describes the message exchanges between a DSP based Access Port, as shown in FIG. 2, and a Wireless Switch.

The following table summarizes message exchanges when the Access Port begins the sequence with a Hello message and at least one Wireless Switch is configured to adopt the Access Port.

			Next
		Desti-	Expected
Message	Source	nation	Message	Notes
Hello	Access	Broad-	Parent
	Port	cast
Parent	Wireless	Access	LoadMe	The FIRST Parent
	Switch	Port		message received
				by the Access
				Port determines
				the Access
				Port's Parent.
LoadMe	Access	Broad-	LoadImage
	Port	cast
Load-	Wireless	Access	Ack	Access Port
Image	Switch	Port		accepts Load-
				Image messages
				only from it's
				Parent.
Ack	Access	Wireless	LoadImage	LoadImage, Ack
	Port	Switch	or	sequence
			LoadDone	continues until
				file download
				completes as
				indicated by
				LoadDone
Load-	Wireless	Access	Device-
Done	Switch	Port	Info
Device-	Access	Broad-	Ack	DeviceInfo
Info	Port	cast		informs all
				Wireless
				Switches of the
				capabilities of
				the Access Port.
Ack	Wireless	Access	ConfigMe	Access Port
	Switch	Port		accepts Ack only
				from its Parent.
ConfigMe	Access	Wireless	Config-
	Port	Switch	uration
Config-	Wireless	Access	Status
uration	Switch	Port
Status	Access	Wireless		Normal operations
	Port	Switch		begin after this
				point

The following summarizes message exchanges when NO Wireless Switches are configured to adopt the Access Port.

			Next
			Expected
Message	Source	Destination	Message	Notes
Hello	Access	Broad-	Parent	The Access Port
	Port	cast		sends ten Hello
				messages. No
				response is
				received from
				any Wireless
				Switch.
LoadMe	Access	Broad-	LoadImage	The Access Port
	Port	cast		gets its firmware
				download from the
				first Wireless
				Switch to reply
				to the LoadMe.
Load-	Wireless	Access	Ack
Image	Switch	Port
Ack	Access	Wireless	LoadImage	LoadImage, Ack
	Port	Switch	or	sequence
			LoadDone	continues until
				file download
				completes
				indicated by
				LoadDone
Load-	Wireless	Access	Device-
Done	Switch	Port	Info
Device-	Access	Broad-		DeviceInfo
Info	Port	cast		informs all
				Wireless Switches
				of the capa-
				bilities of the
				Access Port. The
				DeviceInfo
				message is sent
				five times. The
				portal then
				resets.

The following summarizes message exchanges when an Access Port begins the initialization sequence with a LoadMe message rather than a Hello message.

			Next
			Expected
Message	Source	Destination	Message	Notes
LoadMe-	Access	Broad-	LoadImage-	The Access Port
old	Port	cast	old	gets its
				firmware
				download from
				the first
				Wireless Switch
				to reply to the
				LoadMe.
Load-	Wireless	Access	Ack-old
Image-	Switch	Port
old
Ack-old	Access	Wireless	LoadImage-	LoadImage, Ack
	Port	Switch	old or	sequence
			LoadDone-	continues until
			old	file download
				completes
				as indicated
				by LoadDone
Load-	Wireless	Access	Device-
Done-	Switch	Port	Info
old
Device-	Access	Broad-	Ack	The Parent
Info	Port	cast		field of the
				DeviceInfo
				message does
				not exist.
				If a Wireless
				Switch chooses
				to Adopt this
				Access Port,
				the Wireless
				Switch
				responds to the
				DeviceInfo with
				an Ack.
Ack	Wireless	Access	Device-	This Ack
	Switch	Port	Info	informs
				the Access Port
				that the
				Wireless Switch
				is now its
				“Parent”.
Device-	Access	Broad-	Ack	The Parent
Info	Port	cast		field of this
				DeviceInfo
				message now
				contains the
				MAC address of
				the
				Wireless Switch
				that sent the
				above Ack.
Ack	Wireless	Access	ConfigMe	This Ack
	Switch	Port		confirms the
				adoption.
ConfigMe	Access	Wireless	Config-
	Port	Switch	uration
Config-	Wireless	Access	Status
uration	Switch	Port
Status	Access	Wireless		Normal
	Port	Switch		operations
				begin after
				this point

After each portal is configured, it begins normal operation. During normal operation with no traffic, the Wireless Switch sends a “Heartbeat” message to each portal once per second. The portal sends a “status” message to the Wireless Switch every 5 s.

Access Port		Wireless Switch
1)		<--	Heartbeat (1)
2)		<--	Heartbeat (2)
3)		<--	Heartbeat (1)
4)		<--	Heartbeat (2)
5)		<--	Heartbeat (1)
6)		<--	Heartbeat (2)
7)		<--	Heartbeat (1)
8)		<--	Heartbeat (2)
9)		<--	Heartbeat (1)
10)		<--	Heartbeat (2)
11)	Status (1)	-->
12)	Status (2)	-->

If any portal misses the Heartbeat for 10 s, the Access Port resets and starts again at phase 1.

During normal operation, if an 802.11a radio detects radar, transmission on the current channel will cease. The 802.11a portal will send a Status message with a “radar detect” indication. At this point, normal forwarding operations will cease. The Access Port will remain in this state (as if no Active ESS's are defined) until another Configuration message is received from the Wireless Switch. The next Configuration message will determine the next action taken by the Access Port. The next Configuration message may indicate that the Access Port shall perform ACS (described below). The Configuration message may simply indicate which channel to use. In this case, the Access Port shall continue normal operation on the channel indicated in the Configuration message.

The Switch may direct the Access Port to perform ACS at any time. The following steps are involved in the ACS process:

The Switch sends a Configuration message to Access Port with the Automatic Channel Scan bit set. The ACS bit is in the Option Mask field (Element ID 0x2E) of the Configuration message. When this message is received by the Access Port, all normal forwarding operations will cease. This will be operationally identical to having no Active ESS. The Heartbeat and Status message exchanges will continue during ACS.

In the same Configuration message, the Allowed Channels Field (0x2F) will define the list of channels (one or more) to use in the process.

When the Access Port begins the process, the Access Port will send a Status message to the Wireless Switch with the Auto Channel scan field (0×50) set to 0xffff.

The Access Port will start with the first channel indicated in the Allowed Channels Field (0x2F), and sequentially process each channel as follows:

• • 1) The Access Port will “listen” for 200 milliseconds. The Access Port will encapsulate each beacon heard on the channel in a WISP header and send it to the Wireless Switch. The WISP frame format will indicate the channel on which the beacon was heard, as indicated in Table 61 and the received signal strength (RSSI), as indicated in FIG. 63.
  • 2) If radar is detected during ACS, a Status message will be sent from the Access Port to the Wireless Switch with the Radar Detect (0×53) indication.
  • 3) At any point during ACS, the Wireless Switch may send a Reset (Command 0x8002).
  • 4) When all channels indicated in the Allowed Channels Field (0x2F) have been processed by the Access Port, the Access Port will send a Status message to the Wireless Switch with the Auto channel scan field set to 0×FFFE. This informs the Wireless Switch that that the scan process is complete and no more beacons will forwarded.
  • 5) When the Wireless Switch receives Status message indicating “Scan Complete”, the Wireless Switch will evaluate the forwarded beacons (and any Radar Detect indications). When the evaluation is complete, the Wireless Switch will send a new Configuration Packet to the Access Port that indicates the Selected Channel.
  • 6) As soon as the newly indicated channel becomes effective, the Access Port will send a Status message that indicates the new Configuration Sequence number (0x51), and the number of the assigned channel (0x50). At this point normal forwarding operations continue.

Several messages sent by the Access Port have timeouts, repeat intervals, and differing behaviors depending on whether they timeout or receive the expected response. The following is a summary. A Reset returns the Access Port to the Access port Adoption Process.

					Action after
	Expected Response			Action after	timeout waiting
Message from	Message from	Repeat	Expiration	Expected	for Expected
Access Port	Wireless Switch	Interval	Time	Response	Response
Hello	Parent	1 Sec	10 Sec	Send LoadMe	Send LoadMe
				with a non-	with a NULL
				null Parent	parent field
				field
LoadMe	LoadImage	1 Sec	10 Sec	Send next	Reset
				LoadMe
LoadMe	LoadDone	1 Sec	10 Sec	Send	Reset
				DeviceInfo
DeviceInfo	Ack	1 Sec	10 Sec	Send	Reset
				ConfigMe
ConfigMe	Configuration	3 Sec	9 Sec	Start normal	Reset
				operation
Status	None	5 Sec	None	None	None
Unsolicited	Heartbeat	1 Sec	10 Sec	Update	Reset
				Heartbeat Info

The sequence number field in the Wireless Data Packet is used to detect packets that have gotten out of order due to possible differing paths through the switch fabric between a Wireless Switch and a Radio. Each entity (Wireless Switch and Radio) must keep track of the sequence number of the last Wireless Data Packet that it received. If it receives a Wireless Data Packet with a sequence number that is lower than the last it received, it must discard that packet. Care must be taken to ensure that this mechanism works through wrap-around of the sequence number back to zero.

While there have been described what are believed to be the preferred embodiments of the present invention, those skilled in the art will recognize that other and further changes and modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falls in the scope of the invention.

Claims

1. In a wireless local area network, wherein a wireless switch controls the operation of one or more access ports and manages data communications with said one or more access ports, and wherein said access ports include one or more portals for communicating data to other devices, an improved method for configuring said access ports, comprising: downloading software from said wireless switch for operation of said access port; signaling data from said access port representing the identification of said one or more portals of said access port; and downloading data from said wireless switch to said access port to configure said one or more portals of said access port.

2. An access port configured according to the method of claim 1.

3. In a wireless local area network, wherein a wireless switch controls the operation of one or more access ports and manages data communications with said one or more access ports, and wherein at least one of said access ports includes an access port processor and a plurality of portals for communicating data to other devices, an improved method for data communications between said wireless switch and devices communicating with said portals, comprising: providing separate network addresses corresponding to each of said access port and said portals; communicating messages between said access port processor and said wireless switch using a network address corresponding to said access port; and communicating messages between said portals and said wireless switch using network addresses assigned to said portals.

4. A method as specified in claim 3 further comprising assigning sequence numbers to data messages between said access port and said wireless switch, wherein separate series of sequence numbers are assigned to each of said access port processor and said plurality of portals.

5. A method as specified in claim 4 wherein said data messages have an ethernet format, including a first ethernet header and a second header, wherein said ethernet header includes said network address and wherein said second header includes said sequence number.

6. A method as specified in claim 5 wherein said second header includes a message length field.

7. A method as specified in claim 5 wherein said second header includes a command field identifying message direction and message type.

8. A method as specified in claim 6 wherein said second header includes a code field indicating a command code for processing data in the message.

9. A wireless local area network arranged to operate using the method of claim 3.

10. In a wireless local area network, wherein one or more wireless switches control the operation of one or more access ports and manage data communications with said one or more access ports, a method for initiating an association between an access port and a wireless switch, comprising: configuring said wireless switches to selectively adopt access ports; upon initiation of operation of an access port broadcasting a HELLO message identifying a MAC address of said access port; responding to said Hello message with PARENT messages sent by wireless switches configured to adopt said access port, each said PARENT messages identifying a MAC address for said wireless switch; and receiving said PARENT messages at said access port and selecting one of said wireless switches to adopt said access port.

11. A method according to claim 1 wherein selecting a wireless switch comprises selecting a wireless switch sending the PARENT message first received by said access port.

12. An access port configured to carry out the method of claim 10.

13. In a wireless local area network, wherein a wireless switch controls the operation of one or more access ports and manages data communications with said one or more access ports, and wherein said access ports include one or more radio portals for communicating data to other devices, a method for selecting a channel of operation for a radio portals of at least one of said access ports, comprising: sequentially monitoring each of a plurality of possible channels using said radio portal to detect beacon signals on said possible channels; forwarding received beacon signals to a wireless switch controlling operation of said access port having said radio portal; analyzing said received beacon signals using said wireless switch to select a channel for operation of said wireless portal; and sending a configuration message from said wireless switch to said radio portal to configure said radio portal to operate on said selected channel.

14. A method as specified in claim 13 wherein said wireless switch sends a control message to said access port designating said possible channels.

15. A method as specified in claim 13 wherein said access ports send signal strength data to said wireless switch with said received beacon signals.

16. A method as specified in claim 15 wherein said access port sends said received beacon signals to said wireless switch using a signal format identifying a channel on which said beacon signal was received.