Network Working Group P. Calhoun
Internet-Draft B. O'Hara
Expires: November 6, 2004 S. Kelly
R. Suri
Airespace
M. Williams
Nokia, Inc.
M. Vakulenko
Legra Systems, Inc.
May 8, 2004
Light Weight Access Point Protocol (LWAPP)
draft-ohara-capwap-lwapp-00
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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This Internet-Draft will expire on November 6, 2004.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
Wireless Access Points are not strictly Layer 2 bridges. Such
devices may be much simpler, barely more than radios. They may also
perform some additional or higher layer functions such as those
performed by switches and routers. For example, in IEEE 802.11
networks, Access Points can function as Network Access Servers. This
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is one reason Access Points may have IP addresses and function as IP
devices.
This document describes the Light Weight Access Point Protocol which
supports control and management of wireless Access Points. Bindings
for each wireless system specify the protocol as applied to that
technology. An IEEE 802.11 binding is provided in this draft.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Conventions used in this document . . . . . . . . . . . . 6
2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7
3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 Wireless Binding Definition . . . . . . . . . . . . . . . 9
3.2 LWAPP State Machine Definition . . . . . . . . . . . . . . 9
4. LWAPP Packet Definitions . . . . . . . . . . . . . . . . . . . 10
4.1 LWAPP Data Messages . . . . . . . . . . . . . . . . . . . 10
4.2 LWAPP Control Messages Overview . . . . . . . . . . . . . 10
4.2.1 Control Message Format . . . . . . . . . . . . . . . . 10
4.3 Control Channel Management . . . . . . . . . . . . . . . . 12
4.3.1 Discovery Requests . . . . . . . . . . . . . . . . . . 12
4.3.2 Discovery Reply . . . . . . . . . . . . . . . . . . . 13
4.3.3 Join Request . . . . . . . . . . . . . . . . . . . . . 14
4.3.4 Join Reply . . . . . . . . . . . . . . . . . . . . . . 15
4.3.5 Echo Request . . . . . . . . . . . . . . . . . . . . . 15
4.3.6 Echo Response . . . . . . . . . . . . . . . . . . . . 16
4.3.7 Key Update Request . . . . . . . . . . . . . . . . . . 16
4.3.8 Key Update Response . . . . . . . . . . . . . . . . . 17
4.3.9 Key Update Trigger . . . . . . . . . . . . . . . . . . 17
4.4 AR Configuration . . . . . . . . . . . . . . . . . . . . . 18
4.4.1 Configure Request . . . . . . . . . . . . . . . . . . 18
4.4.2 Configure Response . . . . . . . . . . . . . . . . . . 18
4.4.3 Configuration Update Request . . . . . . . . . . . . . 19
4.4.4 Configuration Update Response . . . . . . . . . . . . 20
4.4.5 Statistics Report . . . . . . . . . . . . . . . . . . 20
4.4.6 Statistics Response . . . . . . . . . . . . . . . . . 21
4.4.7 Reset Request . . . . . . . . . . . . . . . . . . . . 21
4.4.8 Reset Response . . . . . . . . . . . . . . . . . . . . 21
4.5 Mobile Session Management . . . . . . . . . . . . . . . . 22
4.5.1 Add Mobile Request . . . . . . . . . . . . . . . . . . 22
4.5.2 Add Mobile Response . . . . . . . . . . . . . . . . . 23
4.5.3 Delete Mobile Request . . . . . . . . . . . . . . . . 23
4.5.4 Delete Mobile Response . . . . . . . . . . . . . . . . 24
4.6 Firmware Management . . . . . . . . . . . . . . . . . . . 24
4.6.1 Image Data Request . . . . . . . . . . . . . . . . . . 24
4.6.2 Image Data Response . . . . . . . . . . . . . . . . . 25
5. LWAPP Message Elements . . . . . . . . . . . . . . . . . . . . 26
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5.1 Result Code . . . . . . . . . . . . . . . . . . . . . . . 27
5.2 AR Address . . . . . . . . . . . . . . . . . . . . . . . . 27
5.3 AP Descriptor . . . . . . . . . . . . . . . . . . . . . . 27
5.4 AP Name . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.5 AR Descriptor . . . . . . . . . . . . . . . . . . . . . . 28
5.6 Binding AP WLAN Radio Configuration . . . . . . . . . . . 29
5.7 Binding Rate Set . . . . . . . . . . . . . . . . . . . . . 29
5.8 Binding Multi-domain Capability . . . . . . . . . . . . . 29
5.9 Binding MAC Operation . . . . . . . . . . . . . . . . . . 29
5.10 Binding Tx Power Level . . . . . . . . . . . . . . . . . . 29
5.11 Binding Direct Sequence Control . . . . . . . . . . . . . 30
5.12 Binding OFDM Control . . . . . . . . . . . . . . . . . . . 30
5.13 Binding Supported Rates . . . . . . . . . . . . . . . . . 30
5.14 Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5.15 Administrative State . . . . . . . . . . . . . . . . . . . 30
5.16 Delete WLAN . . . . . . . . . . . . . . . . . . . . . . . 30
5.17 AR Name . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.18 Image Download . . . . . . . . . . . . . . . . . . . . . . 31
5.19 Image Data . . . . . . . . . . . . . . . . . . . . . . . . 31
5.20 Location Data . . . . . . . . . . . . . . . . . . . . . . 31
5.21 Statistics Timer . . . . . . . . . . . . . . . . . . . . . 32
5.22 Binding Statistics . . . . . . . . . . . . . . . . . . . . 32
5.23 Binding Antenna . . . . . . . . . . . . . . . . . . . . . 32
5.24 Certificate . . . . . . . . . . . . . . . . . . . . . . . 32
5.25 Session ID . . . . . . . . . . . . . . . . . . . . . . . . 32
5.26 Session Key Payload . . . . . . . . . . . . . . . . . . . 32
5.27 Binding WLAN Create . . . . . . . . . . . . . . . . . . . 33
5.28 Vendor Specific Payload . . . . . . . . . . . . . . . . . 33
5.29 Binding Tx Power . . . . . . . . . . . . . . . . . . . . . 33
5.30 Add Mobile . . . . . . . . . . . . . . . . . . . . . . . . 34
5.31 Delete Mobile . . . . . . . . . . . . . . . . . . . . . . 34
5.32 Binding Mobile Session Key . . . . . . . . . . . . . . . . 35
6. LWAPP Configuration Variables . . . . . . . . . . . . . . . . 36
6.1 MaxDiscoveryInterval . . . . . . . . . . . . . . . . . . . 36
6.2 MaxDiscoveries . . . . . . . . . . . . . . . . . . . . . . 36
6.3 SilentInterval . . . . . . . . . . . . . . . . . . . . . . 36
6.4 NeighborDeadInterval . . . . . . . . . . . . . . . . . . . 36
6.5 EchoInterval . . . . . . . . . . . . . . . . . . . . . . . 36
6.6 DiscoveryInterval . . . . . . . . . . . . . . . . . . . . 37
7. LWAPP Transport Layers . . . . . . . . . . . . . . . . . . . . 38
7.1 Using IEEE 802.3 MAC as LWAPP transport . . . . . . . . . 38
7.1.1 Framing . . . . . . . . . . . . . . . . . . . . . . . 38
7.1.2 AR Discovery . . . . . . . . . . . . . . . . . . . . . 38
7.1.3 Fragmentation/Reassembly . . . . . . . . . . . . . . . 38
7.1.4 Multiplexing . . . . . . . . . . . . . . . . . . . . . 39
7.1.5 LWAPP Message Header format over IEEE 802.3 MAC
transport . . . . . . . . . . . . . . . . . . . . . . 39
7.2 Using IPv4/UDP as LWAPP transport . . . . . . . . . . . . 40
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7.2.1 Framing . . . . . . . . . . . . . . . . . . . . . . . 40
7.2.2 AR Discovery . . . . . . . . . . . . . . . . . . . . . 40
7.2.3 Fragmentation/Reassembly . . . . . . . . . . . . . . . 41
7.2.4 Multiplexing . . . . . . . . . . . . . . . . . . . . . 41
7.2.5 LWAPP Message Header format over IPv4/UDP transport . 42
8. Light Weight Access Protocol Constants . . . . . . . . . . . . 43
9. Security Considerations . . . . . . . . . . . . . . . . . . . 44
10. IPR Statement . . . . . . . . . . . . . . . . . . . . . . . 45
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 46
A. Session Key Generation . . . . . . . . . . . . . . . . . . . . 48
A.1 Securing AP-AR communications . . . . . . . . . . . . . . 48
A.2 Authenticated Key Exchange . . . . . . . . . . . . . . . . 49
A.3 Refreshing Cryptographic Keys . . . . . . . . . . . . . . 50
B. Wireless Bindings . . . . . . . . . . . . . . . . . . . . . . 52
B.1 IEEE 802.11 Binding . . . . . . . . . . . . . . . . . . . 52
B.1.1 Transport specific bindings . . . . . . . . . . . . . 52
B.1.2 Data Message bindings . . . . . . . . . . . . . . . . 53
B.1.3 Control Message bindings . . . . . . . . . . . . . . . 53
B.1.4 Message Element Bindings . . . . . . . . . . . . . . . 55
Intellectual Property and Copyright Statements . . . . . . . . 66
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1. Introduction
Unlike wired network elements, Access Points (AP) require a set of
management and control functions related to their primary task of
connecting the wireless and wired mediums. Today, protocols for
managing APs are either Layer 2 specific or non-existent (if the APs
are self-contained). The emergence of simple 802.11 APs that are
managed by a router or switch (also known as an Access Router, or AR)
suggests that having a standardized, interoperable protocol could
radically simplify the deployment and management of wireless
networks. In many cases the overall control and management functions
themselves are generic and could apply to any wireless Layer 2
protocol. Being independent of specific wireless Layer 2
technologies, such a protocol could better support interoperability
between Layer 2 devices and enable smoother intertechnology
handovers.
The details of how these functions would be implemented are dependent
on the particular Layer 2 wireless technology. Such a protocol would
need provisions for binding to specific technologies.
LWAPP assumes a network configuration that consists of multiple APs
communicating either via layer 2 (MAC) or layer 3 (IP) to an AR. The
AP can be considered as remote RF interfaces, being controlled by the
AR. The AR forwards all L2 frames it wants to transmit to an AP via
the LWAPP protocol. Packets from mobile nodes are forwarded by the
AP to the AR, also via this protocol. Figure 1illustrates this
arrangement as applied to an IEEE 802.11 binding.
+-+ 802.11frames +-+
| |--------------------------------| |
| | +-+ | |
| |--------------| |---------------| |
| | 802.11 PHY/ | | LWAPP | |
| | MAC sublayer | | | |
+-+ +-+ +-+
STA AP AR
Figure 1: LWAPP Architecture
Security is another aspect of Access Point management that is not
well served by existing solutions. Provisioning APs with security
credentials, and managing which APs are authorized to provide service
are today handled by proprietary solutions. Allowing these functions
to be performed from a centralized router or switch in an
interoperable fashion increases managability and allows network
operators to more tightly control their wireless network
infrastructure.
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This document describes the Light Weight Access Point Protocol
(LWAPP), allowing an AR to manage a collection of APs. The protocol
is defined to be independent of Layer 2 technology, but an 802.11
binding is provided for use in growing 802.11 wireless LAN networks.
Goals
The following are goals for this protocol:
1. Centralization of the bridging, forwarding, authentication,
encryption and policy enforcement functions for a wireless
network. This will permit reduced cost and higher efficiency when
applying the capabilities of network processing silicon to the
wireless network, as it has already been applied to wired LANs.
2. Permit shifting of the higher level protocol processing burden
away from the AP. This leaves the computing resource of the AP to
the timing critical applications of wireless control and access.
This makes the most efficient use of the computing power available
in APs that are the subject of severe cost pressure.
3. Providing a generic encapsulation and transport mechanism, the
protocol may be applied to other access point protocols in the
future by adding the binding.
The LWAPP protocol concerns itself solely on the interface between
the AP and the AR. Inter-AR, or mobile to AR communication is
strictly outside the scope of this document.
1.1 Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [7].
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2. Protocol Overview
LWAPP is a generic protocol defining how Access Points communicate
with Access Routers. Access Points and Access Routers may
communicate either by means of Layer 2 protocols or by means of a
routed IP network.
LWAPP messages and procedures defined in this document apply to both
types of transports unless specified otherwise. Transport
independence is achieved by defining formats for both MAC level and
IP level transport (see Section 7). Also defined are framing,
fragmentation/reassembly, and multiplexing services to LWAPP for each
transport type.
The Light Weight Access Protocol (LWAPP) begins with a discovery
phase. The APs send a Discovery Request frame, causing any Access
Router (AR) [8], receiving that frame to respond with a Discovery
Reply. From the Discovery Replies received, an AP will select an AR
with which to associate, using the Join Request and Join Reply. The
Join Request also provides an MTU discovery mechanism, to determine
whether there is support for the transport of large frames between
the AP and it's AR. If support for large frames is not present, the
LWAPP frames will be fragmented to the maximum length discovered to
be supported by the layer 2 network.
Once the AP and the AR have joined, a configuration exchange is
accomplished that will cause both devices to agree on version
information. During this exchange the AP may receive provisioning
settings. For the 802.11 binding, this information would typically
include a name (802.11 Service Set Identifier, SSID), and security
parameters, the data rates to be advertised as well as the radio
channel (channels, if the AP is capable of operating more than one
802.11 MAC and PHY simultaneously) to be used. Finally, the APs are
enabled for operation.
When the AP and AR have completed the version and provision exchange
and the AP is enabled, the LWAPP encapsulates the 802.11 frames sent
between them. LWAPP will fragment its packets, if the size of the
encapsulated 802.11 Data or Management frames causes the resultant
LWAPP packet to exceed the MTU supported between the AP and AR.
Fragmented LWAPP packets are reassembled to reconstitute the original
encapsulated payload.
In addition to the functions thus far described, LWAPP also provides
for the delivery of commands from the AR to the AP for the management
of devices that are communicating with the AP. This may include the
creation of local data structures in the AP for the managed devices
and the collection of statistical information about the communication
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between the AP and the 802.11 devices. LWAPP provides the ability
for the AR to obtain any statistical information collected by the AP.
LWAPP also provides for a keep alive feature that preserves the
communication channel between the AP and AR. If the AR fails to
appear alive, the AP will try to discover a new AR to communicate
through.
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3. Definitions
This Document uses terminology defined in [8]
3.1 Wireless Binding Definition
This draft standard specifies a protocol independent of a specific
wireless access point radio technology. Elements of the protocol are
designed to accommodate specific needs of each wireless technology in
a standard way. Implementation of this standard for a particular
wireless technology must follow the binding requirements defined for
that technology.
3.2 LWAPP State Machine Definition
The following state diagram represents the lifecycle of an AP-AR
session:
+------+(--------------------------------\
| Idle | |
+------+ |
/ +---------+--)+------------+ |
/ | Run | | Key Update | |
v +---------+(--+------------+ |
+-----------+ ^ | | |
| Discovery | | v \----------->+-------+
+-----------+ +-----------+ | Reset |
| ^ \ /--)| Configure | +-------+
v | \ / +-----------+ ^
+---------+ v / |
| Sulking | +------+ +------------+ |
+---------+ | Join |------------)| Image Data |--/
+------+ +------------+
Figure 2: LWAPP State Machine
Each of the states above correspond to an LWAPP control message type,
defined later in this document.
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4. LWAPP Packet Definitions
This section contains the packet types and format. The LWAPP
protocol is designed to be transport agnostic by specifying packet
formats for both MAC frames and IP packets. An LWAPP packet consists
of an LWAPP Transport Layer packet header followed by an LWAPP
message.
Transport details can be found in Section 7.
4.1 LWAPP Data Messages
An LWAPP data message is a forwarded wireless frame. When forwarding
wireless frames, LWAPP is light weight and encapsulates the frames
only in the transport layer header.
4.2 LWAPP Control Messages Overview
The LWAPP Control protocol provides a control channel between the AP
and the AR. The control channel is the series of control messages
between the AP and AR, associated with a session ID and key. Control
is divided into the following distinct message types. Control
Channel, AR Configuration and Mobile Session Management MUST be
implemented. Firmware Management MAY be implemented.
Control Channel Management: Messages that fall within this
classification are used for the discovery of ARs by the APs as
well as the establishment and maintenance of an LWAPP control
channel.
AR Configuration: The AR Configuration messages are used by the AR to
push a specific configuration to the APs it has a control channel
with. Messages that deal with the retrieval of statistics from
the AP also fall in this category.
Mobile Session Management: Mobile session management messages are
used by the AR to push specific mobile policies to the AP.
Firmware Management: Messages in this category are used by the AR to
push a new firmware image down to the AP.
4.2.1 Control Message Format
All LWAPP control messages are sent encapsulated within the LWAPP
header (see for example Section 7.1.5 and Section 7.2.5) with the
following header values:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Msg Type | Seq Num | Msg Element Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Session ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Msg Element [0..N] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2.1.1 Message Type
The Message Type field identifies the function of the LWAPP control
message. The valid values for Message Type are the following:
Description Value
Discovery Request 1
Discovery Reply 2
Join Request 3
Join Reply 4
Configure Request 5
Configure Response 6
Configuration Update Request 7
Configuration Update Response 8
Statistics Report 9
Statistics Report Response 10
Reserved 11-16
Echo Request 17
Echo Response 18
Image Data Request 19
Image Data Response 20
Reset Request 21
Reset Response 22
Key Update Request 23
Key Update Response 24
Reserved 25-26
Key Update Trigger 27
4.2.1.2 Sequence Number
The Sequence Number Field is an identifier value to match request/
response packet exchanges. When an LWAPP packet with a request
message type is received, the value of the sequence number field is
copied into the corresponding response packet.
4.2.1.3 Message Element Length
The Length field indicates the number of bytes following the Session
ID field.
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4.2.1.4 Session ID
The Session ID is a 32-bit unsigned integer that is used to identify
the security context for encrypted exchanges between the AP and the
AR.
4.2.1.5 Message Element[0..N]
The message element(s) carry the information pertinent to each of the
control message types. The total length of the message elements is
indicated in the Message Element Length field.
The format of a message element uses the TLV format shown here:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where Type (8 bit) identifies the character of the information
carried in the Value field and Length (16 bits) indicates the number
of bytes in the Value field.
The LWAPP message elements are defined in Section 5
4.3 Control Channel Management
The Control Channel Management messages are used by the AP and AR to
create and maintain a channel of communication on which various other
commands may be transmitted, such as configuration, firmware update,
etc.
4.3.1 Discovery Requests
The Discovery Request is used by the AP to automatically discovery
potential ARs available in the network. An AP must transmit this
command even if it has a statically configured AR, as it is a
required step in the LWAPP state machine.
4.3.1.1 Sending Discovery Requests
Discovery Requests MUST be sent by an AP in the Discover state after
waiting for a random delay less than MaxDiscoveryInterval, after an
AP first comes up or is (re)initialized. An AP MUST send no more
than a maximum of MaxDiscoveries discoveries, waiting for a random
delay less than MaxDiscoveryInterval between each successive
discovery.
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This is to prevent an explosion of AP Discoveries. An example of
this occurring would be when many APs are powered on at the same
time.
Discovery requests MUST be sent by an AP when no echo responses are
received for NeighborDeadInterval and the AP returns to the discover
state. Discovery requests are sent after NeighborDeadInterval, they
MUST be sent after waiting for a random delay less than
MaxDiscoveryInterval. An AP MAY send up to a maximum of
MaxDiscoveries discoveries, waiting for a random delay less than
MaxDiscoveryInterval between each successive discovery.
If a discovery response is not received after sending the maximum
number of discovery requests, the AP enters the Sulking state and
MUST wait for an interval equal to SilentInterval before sending
further discovery requests.
The Discovery Request message may be sent as a unicast, broadcast or
multicast message.
TODO: Specify exponential backoff of discovery requests.
4.3.1.2 Format of a Discovery Request
The Discovery Request carries the following message elements:
AP
Radio Payload (one for each radio in the AP)
4.3.1.3 Receiving Discovery Requests
Upon receiving a discovery request, the AR will respond with a
Discovery Reply sent to the address in the source address of the
received discovery request.
4.3.2 Discovery Reply
The Discovery Reply is a mechanism by which an AR advertises its
services to requesting APs.
4.3.2.1 Sending Discovery Replies
Discovery Replies are sent by an AR after receiving a Discovery
Request.
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4.3.2.2 Format of a Discovery Reply
The Discovery Reply carries the following message elements:
AR
AR Name
4.3.2.3 Receiving Discovery Replies
When an AP receives a Discovery Reply, it MUST wait for an interval
not less than DiscoveryInterval for receipt of additional discovery
replies. After the DiscoveryInterval elapses, the AP enters the
Joining state and will select one of the ARs that sent a discovery
reply and send a Join Request to that AR.
4.3.3 Join Request
The Join Request is used by an AP to inform an AR that it wishes to
provide services through it.
4.3.3.1 Sending Join Requests
Join Requests are sent by an AP in the Joining state after receiving
one or more Discovery Replies. The Join Request is also used as an
MTU discovery mechanism by the AP. The AP issues a Join Request with
a Test message element, bringing the total size of the message to
exceed MTU.
The initial Join Request is padded with the Test message element to
1596 bytes. If a Join Reply is received, the AP can forward frames
without requiring any fragmentation. If no Join Reply is received,
it issues a second Join Request padded with the Test payload to a
total of 1500 bytes. The AP continues to cycle from large (1596) to
small (1500) packets until a Join Reply has been received, or until
both packets sizes have been retransmitted 3 times. If the Join
Reply is not received after the maximum number of retransmissions,
the AP MUST abandon the AR and restart the discovery phase.
4.3.3.2 Format of a Join Request
The Join Request carries the following message elements:
AR Address
AP Descriptor
AP Name Payload
Location Data
Radio Payload (one for each radio)
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Certificate
Session ID
Test
4.3.3.3 Receiving Join Requests
When an AR receives a Join Request it will respond with a Join Reply.
The AR validates the certificate found in the request. If valid, the
AR generates a session key which will be used to secure the control
frames it exchanges with the AP. When the AR issues the Join Reply,
the AR creates a context for the session with the AP.
Details on the key generation is found in appendix A.
4.3.4 Join Reply
The Join Reply is sent by the AR to indicate to an AP whether it is
capable and willing to provide service to it.
4.3.4.1 Sending Join Replies
Join Replies are sent by the AR after receiving a Join Request. Once
the Join Reply has been sent, the heartbeat timer is initiated for
the session. Expiration of the timer will result in delete of the
AR-AP session. The timer is refreshed upon receipt of the Echo
Request.
4.3.4.2 Format of a Join Reply
The Join Reply carries the following message elements:
Result Code
Certificate
Session Key
4.3.4.3 Receiving Join Replies
When an AP receives a Join Reply it enters the Joined state and
initiates the Configure Request to the AR to which it is now joined.
Upon entering the Joined state, the AP begins timing an interval
equal to NeighborDeadInterval. Expiration of the timer will result
in the transmission of the Echo Request.
4.3.5 Echo Request
The Echo Request message is a keepalive mechanism for the LWAPP
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control message.
4.3.5.1 Sending Echo Requests
Echo Requests are sent by an AP in the Join or Run state to determine
the state of the connection between the AP and the AR.
4.3.5.2 Format of a Echo Request
The Echo Request carries no message elements.
4.3.5.3 Receiving Echo Requests
When an AR receives an Echo Request it responds with a Echo Response.
4.3.6 Echo Response
The Echo Response acknowledges the Echo Request.
4.3.6.1 Sending Echo Responses
Echo Responses are sent by an AR after receiving an Echo Request.
4.3.6.2 Format of a Echo Response
The Echo Response carries no message elements.
4.3.6.3 Receiving Echo Responses
When an AP receives an Echo Response it resets the timer that is
timing the NeighborDeadInterval. If the NeighborDeadInterval timer
expires prior to receiving an Echo Response, the AP enters the
Discovery state.
4.3.7 Key Update Request
The Key Update Request updates the LWAPP session key used to secure
messages between the AP and the AR.
4.3.7.1 Sending Key Update Requests
Key Update Requests are sent by an AP in the Run state to update a
session key. The Session ID message element MUST include a new
session identifier.
4.3.7.2 Format of a Key Update Request
The Key Update Request carries the following message elements:
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Session ID
4.3.7.3 Receiving Key Update Requests
When an AR receives a Key Update Request it generates a new key (see
appendix A) and responds with a Key Update Response.
4.3.8 Key Update Response
The Key Update Response updates the LWAPP session key used to secure
messages between the AP and the AR, and acknowledges the Key Update
Request.
4.3.8.1 Sending Key Update Responses
Key Update Responses are sent by a AR after receiving a Key Update
Request. The Key Update Responses is secured using public key
cryptography.
4.3.8.2 Format of a Key Update Response
The Key Update Response carries the following message elements:
Session Key
4.3.8.3 Receiving Key Update Responses
When an AP receives a Key Update Response it will use the information
contained in the Session Key message element to determine the keying
material used to encrypt the LWAPP communications between the AP and
the AR.
4.3.9 Key Update Trigger
The Key Update Trigger is used by the AR to request that a Key Update
Request be initiated by the AP.
4.3.9.1 Sending Key Update Trigger
Key Update Requests are sent by an AR in the Run state to inform the
AP to initiate a Key Update Request message.
4.3.9.2 Format of a Key Update Trigger
The Key Update Request carries the following message elements:
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Session ID
4.3.9.3 Receiving Key Update Trigger
When a AP receives a Key Update Trigger it generates a key Update
Request.
4.4 AR Configuration
The AR Configuration messages serve two purposes. They are used to
exchange configuration between AR and AP. Thy are also used by the
AR to retrieve statistics from the AP.
4.4.1 Configure Request
The Configure Request message is sent by an AP to send its current
configuration to its AR.
4.4.1.1 Sending Configure Requests
Configure Requests are sent by an AP after receiving a Join Reply.
4.4.1.2 Format of a Configure Request
The Configure Request carries binding specific message elements.
Refer to the appropriate binding for the definition of this
structure.
4.4.1.3 Receiving Configure Requests
When an AR receives a Configure Request it will act upon the content
of the packet and respond to the AP with a Configure Response.
4.4.2 Configure Response
The Configure Response message is sent by an AR and provides an
opportunity for the AR to override an AP's requested configuration.
4.4.2.1 Sending Configure Responses
Configure Responses are sent by an AR after receiving a Configure
Request.
4.4.2.2 Format of a Configure Response
The Configure Response carries binding specific message elements.
Refer to the appropriate binding for the definition of this
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structure.
4.4.2.3 Receiving Configure Responses
When an AP receives a Configure Response it acts upon the content of
the packet, as appropriate.
4.4.3 Configuration Update Request
The Configuration Update Request is a message initiated by the AR to
update the configuration of an AP while in the Run state.
4.4.3.1 Sending Configuration Update Requests
Configure Update Requests are sent by the AR to provision the AP
while in the Run state. This is used to modify the configuration of
the AP while it is operational.
4.4.3.2 Format of a Configure Update Request
The Configure Command Request carries any of the following message
elements:
AP Name 4
Reserved 6
Rate Set 8
Multi-domain capability 9
MAC Operation 10
Reserved 11
Tx Power Level 12
Direct Sequence Control 13
OFDM Control 14
Supported Rates 15
Reserved 25
Administrative State 26
Delete WLAN 27
Reserved 28-29
Reserved 33
Location Data 34
Reserved 35
Statistics Timer 36
Session 44
WLAN Payload 50
Vendor Specific 51
Tx Power 52
Add Mobile 53
Delete Mobile 54
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Mobile Session key 55
When an AR receives a Configuration Update Request it will respond
with a Configuration Update Reply, with the appropriate Result Code.
4.4.3.3 Receiving Configuration Update Requests
When an AR receives a Configuration Update Request it will respond
with a Configuration Update Reply, with the appropriate Result Code.
4.4.4 Configuration Update Response
The Configuration Update Response is the acknowledgement message for
the Configuration Update Request.
4.4.4.1 Sending Configuration Update Responses
Configuration Update Responses are sent by an AP after receiving a
Configuration Update Request.
4.4.4.2 Format of a Configuration Update Response
The Configuration Update Response carries the following message
elements:
Result Code 1
4.4.4.3 Receiving Configure Update Responses
When an AR receives a Configure Update Response the result code
indicates if the AP successfully accepted the configuration.
4.4.5 Statistics Report
Statistics Reports are used for statistics collection at the AR.
4.4.5.1 Sending Statistics Reports
Statistics Reports are sent by an AP periodically, based on the
configuration, to transfer statistics to the AR.
4.4.5.2 Format of a Statistics Report
The Statistics Report carries the following message elements:
Statistics
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When an AR receives a Statistics Report it will respond with a
Statistics Response.
4.4.5.3 Receiving Statistics Report
When an AR receives a Statistics Report it will respond with a
Statistics Response.
4.4.6 Statistics Response
Statistics Response acknowledges the Statistics Report.
4.4.6.1 Sending Statistics Responses
Statistics Responses are sent by an AR after receiving a Statistics
Report.
4.4.6.2 Format of a Statistics Response
The Statistics Response carries no message elements.
4.4.6.3 Receiving Statistics Responses
The Statistics Response is simply an acknowledgement of the
Statistics Report.
4.4.7 Reset Request
The Reset Request is used to cause an AP to reboot.
4.4.7.1 Sending Reset Requests
Reset Requests are sent by an AR to cause an AP to reinitialize its
operation.
4.4.7.2 Format of a Reset Request
The Reset Request carries no message elements.
4.4.7.3 Receiving Reset Requests
When an AP receives a Reset Request it will respond with a Reset
Response and then reinitialize itself.
4.4.8 Reset Response
The Reset Response acknowledges the Reset Request.
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4.4.8.1 Sending Reset Responses
Reset Responses are sent by an AP after receiving a Reset Request.
4.4.8.2 Format of a Reset Response
The Reset Response carries no message elements. Its purpose is to
acknowledge the receipt of the Reset Request.
4.4.8.3 Receiving Reset Responses
When an AR receives a Reset Response it is notified that the AP will
now reinitialize its operation.
4.5 Mobile Session Management
Messages in this section are used by the AR to create session state
on the APs.
4.5.1 Add Mobile Request
The Add Mobile Request is used by the AR to inform an AP that it
should forward traffic from a particular mobile station. The add
mobile request may also include security parameters that must be
enforced by the AP for the particular mobile.
4.5.1.1 Sending Add Mobile Requests
When the AR sends an Add Mobile Request, it includes any security
parameters that may be required. An AR that wishes to update a
mobile's policy on an AP may be done by simply sending a new Add
Mobile Request message.
4.5.1.2 Format of a Add Mobile Request
When sent by the AP, the Add Mobile Request contains the following
message elements:
Add Mobile
Mobile Session Key
4.5.1.3 Receiving Add Mobile Requests
When an AP receives an Add Mobile Request, it must first override any
existing state it may have for the mobile station in question. The
latest Add Mobile Request overrides any previously received messages.
If the Add Mobile message element's Not Authenticated bit is set, the
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AP MUST only allow EAP packets to be forwarded to the AR, and must
drop any other messages. The AP will be notified via an Add Mobile
when it may accept other messages via a new Add Mobile Request from
the AR.
If the Mobile Session Key message element was present, the AP MUST
add the key to its session key table to ensure that all future
packets to the mobile are encrypted using the new key.
There are additional binding specific behaviours for this message.
See the appropriate binding for additional specifications.
4.5.2 Add Mobile Response
The Add Mobile Response is used to acknowledge a previously received
Add Mobile Request, and includes a Result Code message element which
indicates whether an error occured on the AP.
4.5.2.1 Sending Add Mobile Response
Add Mobile Response is sent by the AP as a response to the Add Mobile
Request.
4.5.2.2 Format of a Add Mobile Response
The Add Mobile Response includes the following message element:
Result Code
4.5.2.3 Receiving Add Mobile Response
This message requires no special processing, and is only used to
acknowledge the Add Mobile Request.
4.5.3 Delete Mobile Request
The Delete Mobile Request is used by the AR to inform the AP to
terminate service to a particular mobile station.
4.5.3.1 Sending Delete Mobile Requests
The AR sends the Delete Mobile Request when it determines that
service to the mobile must be terminated. This could occur for
various reasons, including for administrative reaons, as a result of
the fact that the mobile has roamed to another AP, etc.
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4.5.3.2 Format of a Delete Mobile Request
The Delete Mobile Request message must include the following message
element:
Delete Mobile
4.5.3.3 Receiving Delete Mobile Requests
When an AP receives the Delete Mobile Request, it must immediately
terminate service to the mobile station.
There are additional binding specific behaviours for this message.
See the appropriate binding for additional specifications.
4.5.4 Delete Mobile Response
The Delete Mobile Response is used to acknowledge a Delete Mobile
Request.
4.5.4.1 Sending Delete Mobile Response
This message requires no special processing, and is only used to
acknowledge the Delete Mobile Request.
4.5.4.2 Format of a Delete Mobile Response
The Delete Mobile Response message includes the following message
element:
Result Code
4.5.4.3 Receiving Delete Mobile Response
No special processing is required for this packet by the AR.
4.6 Firmware Management
The Firmware Management messages are used by the AR to ensure that
the image being run on each AP is appropriate.
4.6.1 Image Data Request
The Image Data Request is used to update firmware on the AP.
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4.6.1.1 Sending Image Data Requests
Image Data Requests are exchanged between the AP and the AR to
download a new program image to an AP.
4.6.1.2 Format of a Image Data Request
When sent by the AP, the Image Data Request contains the following
message elements:
Image Download
When sent by the AR, the Image Data Request contains the following
message elements:
Image Data
4.6.1.3 Receiving Image Data Requests
When an AP or AR receives an Image Data Request it will respond with
a Image Data Response.
4.6.2 Image Data Response
The Image Data Response acknowledges the Image Data Request.
4.6.2.1 Sending Image Data Response
An Image Data Responses is sent in response to an Image Data Request.
Its purpose is to acknowledge the receipt of the Image Data Request
packet.
4.6.2.2 Format of an Image Data Response
The Image Data Response carries no message elements.
4.6.2.3 Receiving Image Data Responses
No action is necessary on receipt.
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5. LWAPP Message Elements
As previously specified, the LWAPP messages MAY include one or more
message elements. The message element types are defined in this
section.
The specified values for the Type field are the following:
Description Type
Result Code 1
AR Address 2
AP Descriptor 3
AP Name 4
AR Descriptor 5
Reserved 6
Binding AP WLAN Radio Configuration 7
Binding Rate Set 8
Binding Multi-domain capability 9
Binding MAC Operation 10
Reserved 11
Binding Tx Power Level 12
Binding Direct Sequence Control 13
Binding OFDM Control 14
Supported Rates 15
Reserved 16
Test 17
Reserved 18-25
Administrative State 26
Delete WLAN 27
Reserved 28-29
AR Name 30
Image Download 31
Image Data 32
Reserved 33
Location Data 34
Reserved 35
Statistics Timer 36
Binding Statistics 37
Binding Antenna xx
Reserved 38-42
Certificate 43
Session 44
Session key 45
Reserved 46-49
Binding WLAN Create 50
Vendor Specific 51
Binding Tx Power 52
Add Mobile 53
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Delete Mobile 54
Mobile Session key 55
5.1 Result Code
The result code message element value is a 32-bit integer value,
indicating the result of the request operation corresponding to the
sequence number in the message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Result Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Result Code: The following values are defined:
0 Success
1 Failure
5.2 AR Address
The AR address message element is used to communicate the identity of
the AR. The value contains two fields, as shown.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved: MUST be set to zero
Mac Address: The MAC Address of the AR
5.3 AP Descriptor
The AP descriptor message element is used by the AP to communicate
it's current hardware/firmware configuration. The value contains the
following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hardware Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Software Version |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Boot Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max Radios | Radios in use | Encryption Capabilities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Hardware Version: A 32-bit integer representing the AP's hardware
version number
Software Version: A 32-bit integer representing the AP's Firmware
version number
Boot Version: A 32-bit integer representing the AP's boot loader's
version number
Max Radios: An 8-bit value representing the number of radios (where
each radio is identified via the RID field) supported by the AP
Radios in use: An 8-bit value representing the number of radios
present in the AP
Encryption Capabilities: This 16-bit field is used by the AP to
communicate it's capabilities to the AR. Since most APs support
link layer encryption, the AR may make use of these services.
There are binding dependent encryption capabilites. Refer to the
specific binding for the specification. This bitfield also
defines the following binding-independent values:
4 - Encrypt AES-CCM 128: All packets to/from the mobile station
must be encrypted using 128 bit AES CCM [11].
5 - Encrypt TKIP-MIC: All packets to/from the mobile station must
be encrypted using TKIP and authenticated using Michael [9].
5.4 AP Name
The AP name message element value is a variable length byte string.
The string is NOT zero terminated.
5.5 AR Descriptor
The AR payload message element is used by the AR to communicate it's
current state. The value contains the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Hardware Version ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HW Ver | Software Version ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SW Ver | Stations | Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Limit | Radios | Max Radio |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Max Radio |
+-+-+-+-+-+-+-+-+
Hardware Version: A 32-bit integer representing the AP's hardware
version number
Software Version: A 32-bit integer representing the AP's Firmware
version number
Stations: A 16-bit integer representing number of mobile stations
currently associated with the AR
Limit: A 16-bit integer representing the maximum number of stations
supported by the AR
Radios: A 16-bit integer representing the number of APs currently
attached to the AR
Max Radio: A 16-bit integer representing the maximum number of APs
supported by the AR
5.6 Binding AP WLAN Radio Configuration
The AP WLAN radio configuration is used by the AR to configure a
Radio on the AP. The message element definition is binding specific.
Refer to the appropriate binding for the specification.
5.7 Binding Rate Set
The rate set message element value is sent by the AR and contains the
supported operational rates. The message element definition is
binding specific. Refer to the appropriate binding for the
specification.
5.8 Binding Multi-domain Capability
The multi-domain capability message element is used by the AR to
inform the AP of regulatory limits. The message element definition
is binding specific. Refer to the appropriate binding for the
specification.
5.9 Binding MAC Operation
The MAC operation message element is sent by the AR to set the 802.11
MAC parameters on the AP. The message element definition is binding
specific. Refer to the appropriate binding for the specification.
5.10 Binding Tx Power Level
The Tx power level message element is sent by the AP and contains the
different power levels supported. The message element definition is
binding specific. Refer to the appropriate binding for the
specification.
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5.11 Binding Direct Sequence Control
The direct sequence control message element is a bi-directional
element. When sent by the AP, it contains the current state. When
sent by the AR, the AP MUST adhere to the values. The message
element definition is binding specific. Refer to the appropriate
binding for the specification.
5.12 Binding OFDM Control
The OFDM control message element is a bi-directional element. When
sent by the AP, it contains the current state. When sent by the AR,
the AP MUST adhere to the values. The message element definition is
binding specific. Refer to the appropriate binding for the
specification.
5.13 Binding Supported Rates
The supported rates message element is sent by the AP to indicate the
rates that it supports. The message element definition is binding
specific. Refer to the appropriate binding for the specification.
5.14 Test
The test message element is used as padding to perform MTU discovery,
and MAY contain any value, of any length.
5.15 Administrative State
The administrative event message element is used to communicate the
state of a particular radio. The value contains the following
fields.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Admin State |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Admin State: An 8-bit value representing the administrative state of
the radio. The following values are supported:
0 - Enabled
1 - Disabled
5.16 Delete WLAN
The delete WLAN message element is used to inform the AP that a
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previously created WLAN is to be deleted. The value contains the
following fields:
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | WLAN ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio
WLAN ID: A 16-bit value specifying the WLAN Identifier
5.17 AR Name
The AR name message element contains an ASCII representation of the
AR's identity. The value is a variable length byte string. The
string is NOT zero terminated.
5.18 Image Download
The image download message element is sent by the AP to the AR and
contains the image filename. The value is a variable length byte
string. The string is NOT zero terminated.
5.19 Image Data
The image data message element value contains the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opcode | Checksum | Image Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Image Data ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Opcode: An 8-bit value representing the transfer opcode. The
following values are supported:
3 - Image data is included
5 - An error occurred. Transfer is aborted
Checksum: A 16-bit value containing a checksum of the image data
that follows
Image Data: A variable length firmward data
5.20 Location Data
The location data message element is a variable length byte string
containing user defined location information (e.g. "Next to
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Fridge"). The string is NOT zero terminated.
5.21 Statistics Timer
The statistics timer message element value is used by the AR to
inform the AP of the frequency which it expects to receive updated
statistics.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Statistics Timer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Statistics Timer: A 16-bit unsigned integer indicating the time, in
seconds
5.22 Binding Statistics
The statistics message element is sent by the AP to transmit it's
current statistics. The message element definition is binding
specific. Refer to the appropriate binding for the specification.
5.23 Binding Antenna
The antenna message element is communicated by the AP to the AR to
provide information on the antennas available. The AR MAY use this
element to reconfigure the AP's antennas. The message element
definition is binding specific. Refer to the appropriate binding for
the specification.
5.24 Certificate
The certificate message element value is a byte string containing a
DER-encoded x.509v3 certificate.
5.25 Session ID
The session ID message element value contains a randomly generated
[5] unsigned 32-bit integer.
5.26 Session Key Payload
The Session Key Payload message element is sent by the AR to the AP
and includes the randomly generated session key, which is used to
protect the LWAPP control messages. More details are available in
Appendix A. The value contains the following fields.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Session ID: A 32-bit value defined in the session ID above.
Session Key: A 128-bit value randomly generated session key [5]
5.27 Binding WLAN Create
The WLAN Create message element is used by the AR to define a
wireless LAN on the AP. The message element definition is binding
specific. Refer to the appropriate binding for the specification.
5.28 Vendor Specific Payload
The Vendor Specific Payload is used to communicate vendor specific
information between the AP and the AR. The value contains the
following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Element ID | Value... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Vendor Identifier: A 32-bit value containing the IANA assigned "SMI
Network Management Private Enterprise Codes" [6]
Element ID: A 16-bit Element Idenfier which is managed by the
vendor.
Element ID: Value The value associated with the vendor specific
element.
5.29 Binding Tx Power
The Tx power message element value is bi-directional. When sent by
the AP, it contains the current power level of the radio in question.
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When sent by the AR, it contains the power level the AP MUST adhere
to. The message element definition is binding specific. Refer to
the appropriate binding for the specification.
5.30 Add Mobile
The Add Mobile message element is used by the AR to inform the AP
that it should allow traffic from/to a particular mobile station.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Association ID | MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address | Preamble Mode | WLAN ID |Supported Rates|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Rates |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Not Auth'ted |
+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio
Association ID: A 16-bit value specifying the 802.11 Association
Identifier
MAC Address: The mobile station's MAC Address
Preamble Mode: This field is set by the AR to inform the AP whether
short or long preamble should be used with the mobile station.
The following values are supported:
0 - Long Preamble: Long preamble is to be used by the AP when
communicating with the mobile station.
1 - Short Preamble: Short preamble is to be used by the AP when
communicating with the mobile station.
WLAN ID: A 16-bit value specifying the WLAN Identifier
Supported Rates: The supported rates to be used with the mobile
station.
Not Authenticated: The AR sets this field to one (1) during the
authentication phase to inform the AP the mobile needs to be
authenticated first and should only accept EAP packets.
5.31 Delete Mobile
The Delete Mobile message element is used by the AR to inform an AP
that it should no longer provide service to a particular mobile
station.
0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio
MAC Address: The mobile station's MAC Address
5.32 Binding Mobile Session Key
The Mobile Session Key Payload message element is sent when the AR
determines that encryption between a mobile station and the AP ir
required. This message element MUST NOT be present without the Add
Mobile (see Section 5.30)message element, and MUST NOT be sent if the
AP had not specifically advertised support for the requested
encryption scheme (see Section 5.3). The message element definition
is binding specific. Refer to the appropriate binding for the
specification.
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6. LWAPP Configuration Variables
An AP or AR that implements LWAPP discovery MUST allow for the
following variables to be configured by system management; default
values are specified so as to make it unnecessary to configure any of
these variables in many cases.
6.1 MaxDiscoveryInterval
The maximum time allowed between sending discovery requests from the
interface, in seconds. Must be no less than 2 seconds and no greater
than 180 seconds.
Default: 20 seconds.
6.2 MaxDiscoveries
The maximum number of discovery requests that will be sent after an
AP boots.
Default: 10
6.3 SilentInterval
The minimum time, in seconds, an AP MUST wait after failing to
receive any responses to its discovery requests, before it MAY again
send discovery requests.
Default: 30
6.4 NeighborDeadInterval
The minimum time, in seconds, an AP MUST wait without having received
echo replies to its echo responses, before the destination for the
echo replies may be considered dead. Must be no less than
2*EchoInterval seconds and no greater than 240 seconds.
Default: 60
6.5 EchoInterval
The minimum time, in seconds, between sending echo requests to the AR
with which the AP has joined.
Default: 30
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6.6 DiscoveryInterval
The minimum time, in seconds, that an AP MUST wait after receiving a
discovery reply, before sending a join request.
Default: 5
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7. LWAPP Transport Layers
The LWAPP protocol can operate at layer 2 or 3. For layer 2 support,
the LWAPP messages are carried in a native Ethernet frame. As such,
the protocol is not routable and depends upon layer 2 connectivity
between the AP and the AR. Layer 3 support is provided by
encapsulating the LWAPP messages within UDP.
7.1 Using IEEE 802.3 MAC as LWAPP transport
This section describes how the LWAPP protocol is provided over native
ethernet frames. An LWAPP packet is formed from the MAC frame header
followed by the LWAPP message header.
7.1.1 Framing
Source Address
A MAC address belonging to the interface from which this message is
sent. If multiple source addresses are configured on an interface,
then the one chosen is implementation dependent.
Destination Address
A MAC address belonging to the interface to which this message is to
be sent. This destination address MAY be either an individual
address or a multicast address, if more than one destination
interface is intended.
Ethertype
The Ethertype field is set to 0x88bb.
7.1.2 AR Discovery
When run over IEEE 802.3, LWAPP messages are distributed to a
specific MAC level broadcast domain. The AR discovery mechanism used
with this transport is for an AP to transmit a Discovery Request
message to a broadcast destination MAC address. The ARs will receive
this message and reply based on their policy.
7.1.3 Fragmentation/Reassembly
Fragmentation at the MAC layer is managed using the C,F,L and Frag ID
fields of the LWAPP message header.
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7.1.4 Multiplexing
LWAPP control messages and data messages are distinguished by the C
Bit in the LWAPP message header.
7.1.5 LWAPP Message Header format over IEEE 802.3 MAC transport
The LWAPP message header for data and command messages in the 802.3
MAC transport follows immediately after the MAC header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|VER| RID |C|F|L| Frag ID | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status/WLANs | Payload... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.1.5.1 VER Field (2 bits)
Defines the version of LWAPP used in this packet. The value for this
draft is 0.
7.1.5.2 RID Field (3 bits)
The RID field gives the Radio ID number for this packet. APs with
multiple radios but a single MAC use this to indicate which radio is
associated with the packet.
7.1.5.3 C Bit
The C bit indicates whether this packet carries a data message or a
control message. When this bit is 0, the packet carries an LWAPP
data message in the payload. When this bit is 1, the packet carries
an LWAPp control messwage as defined in section 4 for consumption by
the addressed destination.
7.1.5.4 F Bit
The F bit indicates whether this packet is a fragment. When this bit
is 1, the packet is a fragment and MUST be combined with the other
corresponding fragments to reassemble the complete information
exchanged between the AP and AR.
7.1.5.5 L Bit
The L bit is valid only if the 'F' bit is set and indicates whether
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the packet contains the last fragment of a fragmented exchange
between AP and AR. When this bit is 1, the packet is not the last
fragment. When this bit is 0, the packet is the last fragment.
7.1.5.6 Fragment ID (8 bits)
The Fragment ID is a value assigned to each group of fragments making
up a complete set. The value of Fragment ID is incremented with each
new set of fragments. The Fragment ID wraps to zero after the
maximum value has been used to identify a set of fragments. LWAPP
only supports up to 2 fragments.
7.1.5.7 Length (16 bits)
The length field is the unsigned number of bytes in the Payload.
7.1.5.8 Status and WLANS (16 bits)
The interpretation of this field is binding specific. Refer to the
transport portion of the binding for a wireless technology for the
specification.
7.1.5.9 Payload
This field contains the header for an LWAPP Data Message or LWAPP
Control Message, followed by the data associated with that message.
7.2 Using IPv4/UDP as LWAPP transport
This section defines how LWAPP makes use of IPV4/UDP transport
between the AP and the AR. In case of this transport, the MAC layer
is as standard for an IPv4 packet.
7.2.1 Framing
Communication between AP and AR is established according to the
standard UDP client/server model. The connection is initiated by the
AP (client) to the well-known UDP port of the AR (server) used for
control messages. This UDP port number of the AR is TBD.
7.2.2 AR Discovery
When LWAPP is run over routed IPv4 networks, the AP and the AR do not
need to reside in the same IP subnet (broadcast domain). However, in
the event the peers reside on separate subnets, there must exist a
mechanism for the AP to discover the AR.
As the AP attempts to establish communication with the AR, it sends
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the Discovery Request message and receives the corresponding reply
message from the AR. The AP must send the Discovery Request message
to either the limited broadcast IP address (255.255.255.255) or to
the unicast IP address of the AR. Upon receipt of the message, the
AR issues a Discovery Reply message to the IP address of the AP,
regardless of whether Discovery Request was sent as a broadcast or
unicast message.
Whether the AP uses a limited IP broadcast or unicast IP address is
implementation dependent.
In order for the AP to use a unicast address, it must first obtain
the IP address of the AR. The configuration of the AR's address in
the AP is implementation dependent.
Informative note: Some possibilities are to make use of a vendor
specific DHCP option, DNS name resolution, or even static
provisioning of the AR's IP address in non-volatile storage.
7.2.3 Fragmentation/Reassembly
When LWAPP is implemented at L3, the transport layer uses IP
fragmentation to fragment and reassemble LWAPP messages that are
longer than MTU size used by either AP or AR. The details of IP
fragmentation are covered in [3].
[ed: IP fragmentation may raise security concerns and bring
additional configuration requirements for certain firewalls and NATs.
One alternative is to re-use the layer 2 (application layer)
fragmentation reassembly. Comments are welcomed.]
7.2.4 Multiplexing
LWAPP messages convey control information between AP and AR, as well
as binding specific data frames or binding specific management
frames. As such, LWAPP messages need to be multiplexed in the
transport sub-layer and be delivered to the proper software entities
in the endpoints of the protocol.
In case of Layer 3 connection, multiplexing is achieved by use of
different UDP ports for control and data packets.
As part of Join procedure, the AP and AR may negotiate different UDP
ports, as well as, different IP addresses for data or session
management messages. [ed: details on how to communicate this
information in the protocol is still missing].
In the event the AP and AR are separated by a NAT, with the AP using
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private IP address space, it is the responsibility of the NAT to
manage appropriate UDP port mapping.
7.2.5 LWAPP Message Header format over IPv4/UDP transport
The LWAPP message header for data and command messages using the
IPv4/UDP transport follows immediately after the UDP header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|VER| RID | Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status/WLANS | Payload... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.2.5.1 VER (2 bits)
Defines the version of LWAPP used in this packet. The value for this
draft is 0.
7.2.5.2 RID (3 bits)
The RID field gives the Radio ID number for this packet. APs with
multiple radios but a single IPv4 address use this to indicate which
radio is associated with the packet.
7.2.5.3 Reserved (11 bits)
The reserved field MUST be set to zero.
7.2.5.4 Length (16 bits)
The length field is the unsigned number of bytes in the Payload.
7.2.5.5 Status and WLANS (16 bits)
The interpretation of this field is binding specific. Refer to the
transport portion of the binding for a wireless technology for the
specification.
7.2.5.6 Payload
This field contains the LWAPP Data Message or LWAPP Control Message.
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8. Light Weight Access Protocol Constants
MAX_RESPONSE_DELAY 2 seconds
MAX_SOLICITATION_DELAY 1 second
SOLICITATION_INTERVAL 3 seconds
MAX_SOLICITATIONS 3 transmissions
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9. Security Considerations
LWAPP uses public key cryptography to ensure trust between the AP and
the AR. During the Join phase, the AR generates a session key, which
is used to secure future control messages. The AP does not
participate in the key generation, but public key cryptography is
used to authenticate the resulting key material. A secured delivery
mechanism to place the certificate in the devices is required. In
order to maximize session key security, the AP and AR periodically
update the session keys, which are encrypted using public key
cryptography. This ensures that a potentially previously compromised
key does not affect the security of communication with new key
material.
One question that periodically arises is why the Join Request is not
signed. It was felt that requiring a signature in this messages was
not required for the following reasons:
1. The Join Request is replayable, so requiring a signature doesn't
provide much protection unless the switches keep track of all
previous Join Requests from a given AP. One alternative would
have been to add a timestamp, but this introduces clock
synchronization issues. Further, authentication occurs in a later
exchange anyway (see point 2 below).
2. The AP is authenticated by virtue of the fact that it can decrypt
and then use the session keys (encrypted with its own public key),
so it *is* ultimately authenticated.
3. A signed Join Request provides a potential Denial of Service
attack on the AR, which would have to authenticate each
(potentially malicious) message.
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10. IPR Statement
The IETF has been notified of intellectual property rights claimed in
regard to some or all of the specification contained in this
document. For more information consult the online list of claimed
rights.
Please refer to http://www.ietf.org/ietf/IPR for more information.
11 References
[1] "Advanced Encryption Standard (AES)", November 2001, <FIPS PUB
197>.
[2] "Counter with CBC-MAC (CCM)", January 2003,
<ftp://ftp.isi.edu/internet-drafts/draft-housley-ccm-mode-02.txt>
.
[3] "IP DATAGRAM REASSEMBLY ALGORITHMS", July 1992,
<ftp://ftp.isi.edu/in-notes/rfc815>.
[4] "Key words for use in RFCs to Indicate Requirement Levels",
March 1997, <ftp://ftp.isi.edu/in-notes/rfc2119>.
[5] "Randomness Recommendations for Security", December 1994,
<ftp://ftp.isi.edu/in-notes/rfc1750>.
[6] "Assigned Numbers: RFC 1700 is Replaced by an On-line
Database", January 2002, <ftp://ftp.isi.edu/in-notes/rfc3232>.
[7] "The Internet Standards Process Revision 3", October 1996,
<ftp://ftp.isi.edu/in-notes/rfc2026>.
[8] "Mobility Related Terminology", April 2003,
<ftp://ftp.isi.edu/internet-drafts/draft-ietf-seamoby-terminology-04.txt>
.
[9] "WiFi Protected Access (WPA) rev 1.6", April 2003.
[10] "IEEE Std 802.11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications", 1999.
[11] "IEEE Std 802.11i/3.0: Specification for Enhanced Security",
November 2003.
[12] "Security Architecture for IP, IETF RFC 2401", November 1998,
<http://www.ietf.org/rfc/rfc2401.txt>.
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Authors' Addresses
Pat R. Calhoun
Airespace
110 Nortech Parkway
San Jose, CA 95134
Phone: +1 408-635-2000
EMail: pcalhoun@airespace.com
Bob O'Hara
Airespace
110 Nortech Parkway
San Jose, CA 95134
Phone: +1 408-635-2025
EMail: bob@airespace.com
Scott Kelly
Airespace
110 Nortech Parkway
San Jose, CA 95134
Phone: +1 408-635-2022
EMail: skelly@airespace.com
Rohit Suri
Airespace
110 Nortech Parkway
San Jose, CA 95134
Phone: +1 408-635-2026
EMail: rsuri@airespace.com
Michael Glenn Williams
Nokia, Inc.
313 Fairchild Drive
Mountain View, CA 94043
Phone: +1 650-714-7758
EMail: Michael.G.Williams@Nokia.com
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Michael Vakulenko
Legra Systems, Inc.
3 Burlington Woods Drive
Burlington, MA 01803
Phone: +1 781-272-8400
EMail: michaelv@legra.com
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Appendix A. Session Key Generation
Note: This version only defines a certificate based mechanism to
secure traffic between the AP and the AR. A shared-secret mechanism
will be added in a future version.
A.1 Securing AP-AR communications
While it is generally straightforward to produce network
installations in which the communications medium between the AP and
AR is not accessible to the casual user (e.g. these LAN segments are
isolated, no RJ45 or other access ports exist between the AP and the
AR), this will not always be the case. Furthermore, a determined
attacker may resort to various more sophisticated monitoring and/or
access techniques, thereby compromising the integrity of this
connection.
In general, a certain level of threat on the local (wired) LAN is
expected and accepted in most computing environments. That is, it is
expected that in order to provide users with an acceptable level of
service and maintain reasonable productivity levels, a certain amount
of risk must be tolerated. It is generally believed that a certain
perimeter is maintained around such LANs, that an attacker must have
access to the building(s) in which such LANs exist, and that they
must be able to "plug in" to the LAN in order to access the network.
With these things in mind, we can begin to assess the general
security requirements for AR-AP communications. While an in-depth
security analysis of threats and risks to these communication is
beyond the scope of this document, some discussion of the motivation
for various security-related design choices is useful. The
assumptions driving the security design thus far include the
following:
o AP-AR communications take place over a wired connection which may
be accessible to a sophisticated attacker
o access to this connection is not trivial for an outsider (i.e.
someone who does not "belong" in the building) to access
o if authentication and/or privacy of end to end traffic for which
the AP and AR are intermediaries is required, this may be provided
via IPsec [12].
o privacy and authentication for at least some AP-AR control traffic
is required (e.g. WEP keys for user sessions, passed from AR to
AP)
o the AR can be trusted to generate strong cryptographic keys
AR-AP traffic can be considered to consist of two types: data traffic
(e.g. to or from an end user), and control traffic which is strictly
between the AR and AP. Since data traffic may be secured using IPsec
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(or some other end-to-end security mechanism), we confine our
solution to control traffic. The resulting security consists of two
components: an authenticated key exchange, and control traffic
security encapsulation. The security encapsulation is accomplished
using CCM, described in [2]. This encapsulation provides for strong
AES-based authentication and encryption. The exchange of
cryptographic keys used for CCM is described below.
A.2 Authenticated Key Exchange
The AR and AP accomplish mutual authentication and a cryptographic
key exchange in a single round trip using the JOIN request/response
pair. To accomplish this, the AP includes its identity certificate
(see Section 5.24) and a randomly-generated session ID (see Section
5.25) which functions as a cryptographic nonce in the JOIN request.
The AR verifies the AP's certificate, and replies with its own
identity certificate, and a signed concatenation of the session ID
and and encrypted cryptographic session key. This exchange is
detailed below, using the following notation:
o Kpriv - the private key of a public-private key pair.
o Kpub - the public key of the pair
o M - a clear-text message
o C - a cipher-text message.
o PKCS1(z) - the PKCS#1 encapsulation of z
o E-x{Kpriv, M} - encryption of M using X's private key
o E-x{Kpub, M} - encryption of M using X's public key
o S-x{M} - a digital signature over M produced by X
o V-x{S-x, M} - verification of X's digital signature over M
o D-x{Kpriv, C} - decryption of C using X's private key
o D-x{Kpub, C} - decryption of C using X's public key
o Certificate-AR - AR's Certificate
o Certificate-AP - AP's Certificate
When the AR receives the SessionID value along with the AP's
certificate, it constructs the reply payload as follows:
o Randomly generate enough key material to produce an encryption key
and an authentication hash key (xx bytes in length). [TBD:
detailed key material generation instructions]
o Compute C1 = E-ap{ Kpub , PKCS1(KeyMaterial)}; this encrypts the
PKCS#1-encoded key material with the public key of the AP, so that
only the AP can decrypt it and determine the session keys.
o Compute S1 = S-ar{SessionID|C1}; this computes the AR's digital
signature over the concatenation of the nonce and the encrypted
key material, and can be verified using the public key of the AR,
"proving" that the AR produced this; this forms the basis of trust
for the AP with respect to the source of the session keys.
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o AR sends (Certificate-AR, C1, S1, SessionID) to AP
o AP verifies that SessionID matches an outstanding request
o AP verifies authenticity of Certificate-AR
o AP computes V-ar{S1, SessionID|C1}, verifying the AR's signature
over the session identifier and the encrypted key material
o AP computes PKCS1(KeyMaterial) = D-ar{ Kpriv , C1}, decrypting the
session keys using its private key; since these were encrypted
with the AP's public key, only the AP can successfully decrypt
this.
KeyMaterial is divided into the encryption key and the HMAC key
[TBD: say how] From this point on, all control protocol payloads
between the AP and AR are encrypted and authenticated. The
related payloads are described in the sections above.
A.3 Refreshing Cryptographic Keys
Since AR-AP associations will tend to be relatively long-lived, it is
sensible to periodically refresh the encryption and authentication
keys; this is referred to as "rekeying". When the key lifetime
reaches 95% of the configured value, the rekeying will proceed as
follows:
o AP generates a fresh SessionID value, and constructs a TLV payload
of type SESSION which contains new SessionID and sends it in
KEY-UPDATE message to AR.
o When the AR receives KEY-UPDATE request with SessionID it
constructs the reply payload as follows:
i) Randomly generate enough key material to produce an encryption
key and an authentication hash key (xx bytes in length).
[TBD:detailed key material generation instructions]
ii) Compute C1 = E-ap{ Kpub , PKCS1(KeyMaterial)}; this encrypts
the PKCS#1-encoded key material with the public key of the AP,
so that only the AP can decrypt it and determine the session
keys.
iii) Compute S1 = S-ar{SessionID|C1}; this computes the AR's
digital signature over the concatenation of the sessionId and
the encrypted key material, and can be verified using the
public key of the AR, "proving" that the AR produced this; this
forms the basis of trust for the AP with respect to the source
of the session keys.
iv) AR then sends a KEY-UPDATE-RSP message to the AP using the new
session values.
o AP must maintain session state for the original SessionID and keys
until it receives the KEY-UPDATE-RSP, at which time it clears the
old session.
o If AP does not receive the KEY-UPDATE-RSP within a reasonable
period of time (1 minute?), it will resend the original request
and reset its response timer. If no response occurs by the time
the original session expires, the AP will delete the new and old
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session information, and initiate the DISCOVER process anew.
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Appendix B. Wireless Bindings
Each wireless technology supported by LWAPP has an associated
binding. LWAPP is designed to support multiple wireless technologies
using this method of specification. The binding is divided into
three portions: transport specific, ref. Section 7; LWAPP data
message, ref. Section 4; LWAPP control message, ref. Section 4.
B.1 IEEE 802.11 Binding
B.1.1 Transport specific bindings
All LWAPP transports have the following IEEE 802.11 specific
bindings:
B.1.1.1 Status and WLANS field (16 bits)
The interpretation of this field depends on the direction of
transmission of the packet. Refer to the figure in Section 7.1.5.
Status
When an LWAPP packet is transmitted from an AP to an AR, this field
is called the status field and indicates radio resource information
associated with the frame. When the message is an LWAPP control
message this field is transmitted as zero.
The status field is divided into the signal strength and signal to
noise ratio with which an IEEE 802.11 frame was received, encoded in
the following manner:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RSSI | SNR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RSSI (8 bits)
RSSI is a signed, 8-bit value. It is the received signal strength
indication, in dBm.
SNR (8 bits)
SNR is a signed, 8-bit value. It is the signal to noise ratio of the
received IEEE 802.11 frame, in dB.
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WLANS field (16 bits)
When an LWAPP data message is transmitted from an AR to an AP, this
field indicates on which WLANs the encapsulated IEEE 802.11 frame is
to be transmitted. For unicast packets, this field is not used by
the AP. For broadcast or multicast packets, the AP might require
this information if it provides encryption services.
Given that a single broadcast or multicast packet might need to be
sent to multiple wireless LANs (presumably each with a different
broadcast key), this field is defined as a bit field. A bit set
indicates a WLAN ID (see Section 5.27) which will be sent the data.
The WLANS field is encoded in the following manner:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| WLAN ID(s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
B.1.2 Data Message bindings
There are no LWAPP Data Message bindings for IEEE 802.11.
B.1.3 Control Message bindings
The IEEE 802.11 binding has the following Control Message
definitions. Control Message Bindings are arranged according to the
four Control Message types:
Control Channel Message Bindings
AR Configuration Message Bindings
Mobile Session Management Bindings
Firmware Management Bindings
Refer to Section 5 and to this binding for the generic and binding
specific message element type definitions.
B.1.3.1 Control Channel Message Bindings
There are no Control Channel Message bindings within the Control
Message Bindings for IEEE 802.11.
B.1.3.2 AR Configuration Message Bindings
Configure Request Message
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The Configure Request carries the following message elements:
Administrative State (for the AP)
AR Name
Administrative State (for each radio)
AP WLAN Radio Configuration (for each radio)
Multi-domain Capability (for each radio)
MAC Operation (for each radio)
PHY TX Power (for each radio)
PHY TX Power Level (for each Radio)
PHY DSSS Payload or PHY OFDM Payload (for each radio)
Antenna (for each radio)
Supported Rates (for each radio)
Configure Response Message
The Configure Response carries the following message elements:
Result Code
AP WLAN Radio Configuration (for each radio)
Operational Rate Set (for each radio)
Multi-domain Capability (for each radio)
MAC Operation (for each radio)
PHY Tx Power (for each Radio)
PHY DSSS or PHY OFDM Payload (for each radio)
Antenna (for each radio)
B.1.3.3 Mobile Session Management Bindings
Add Mobile Request
When the AR sends an Add Mobile Request, it includes any security
parameters that may be required. Further, if the AR's policy is that
802.1X (or WPA) is required, it must set the 802.1X only bit in the
Add Mobile message element. An AR that wishes to update a mobile's
policy on an AP may be done by sending a new Add Mobile Request
message.
If 802.1X (or WPA) was established with the mobile station, the AR
will need to push the session key the AP must use for encrypting all
traffic to the mobile, which is included in the Mobile Session Key
message element.
Delete Mobile Request
Any future packets received from the Mobile must result in a
deauthenticate message, as specified in [10].
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B.1.3.4 Firmware Management Bindings
There are no Firmware Management Message bindings within the Control
Message Bindings for IEEE 802.11.
B.1.4 Message Element Bindings
The IEEE 802.11 Message Element binding has the following
definitions:
B.1.4.1 Binding AP WLAN Radio Configuration
The AP WLAN radio configuration is used by the AR to configure a
Radio on the AP. The message element value contains the following
Fields:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Reserved | Occupancy Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CFP Per | CFP Maximum Duration | BSS ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BSS ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BSS ID | Beacon Period | DTIM Per |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Country String |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Reserved: MUST be set to zero
Occupancy Limit: This attribute indicates the maximum amount of
time, in TU, that a point coordinator MAY control the usage of the
wireless medium without relinquishing control for long enough to
allow at least one instance of DCF access to the medium. The default
value of this attribute SHOULD be 100, and the maximum value SHOULD
be 1000
CFP Period: The attribute describes the number of DTIM intervals
between the start of CFPs
CFP Maximum Duration: The attribute describes the maximum duration
of the CFP in TU that MAY be generated by the PCF
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BSSID: The WLAN Radio's MAC Address
Beacon Period: This attribute specifies the number of TU that a
station uses for scheduling Beacon transmissions. This value is
transmitted in Beacon and Probe Response frames
DTIM Period: This attribute specifies the number of beacon intervals
that elapses between transmission of Beacons frames containing a TIM
element whose DTIM Count field is 0. This value is transmitted in
the DTIM Period field of Beacon frames
Country Code: This attribute identifies the country in which the
station is operating. The first two octets of this string is the two
character country code as described in document ISO/IEC 3166- 1. The
third octet MUST be one of the following:
an ASCII space character, if the regulations under which the
station is operating encompass all environments in the country,
an ASCII 'O' character, if the regulations under which the station
is operating are for an outdoor environment only, or
an ASCII 'I' character, if the regulations under which the station
is operating are for an indoor environment only
B.1.4.2 Binding Rate Set
The rate set message element value is sent by the AR and contains the
supported operational rates. It contains the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Rate Set |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Rate Set: The AR generates the Rate Set that the AP is to include in
it's Beacon and Probe messages
B.1.4.3 Binding Multi-domain Capability
The multi-domain capability message element is used by the AR to
inform the AP of regulatory limits. The value contains the following
fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Radio ID | Reserved | First Channel # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Channels | Max Tx Power Level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Reserved: MUST be set to zero
First Channnel #: This attribute indicates the value of the lowest
channel number in the subband for the associated domain country
string.
Number of Channels: This attribute indicates the value of the total
number of channels allowed in the subband for the associated domain
country string.
Max Tx Power Level: This attribute indicates the maximum transmit
power, in dBm, allowed in the subband for the associated domain
country string.
B.1.4.4 Binding MAC Operation
The MAC operation message element is sent by the AR to set the 802.11
MAC parameters on the AP. The value contains the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Reserved | RTS Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Short Retry | Long Retry | Fragmentation Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tx MSDU Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rx MSDU Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Reserved: MUST be set to zero
RTS Threshold: This attribute indicates the number of octets in an
MPDU, below which an RTS/CTS handshake MUST NOT be performed. An
RTS/CTS handshake MUST be performed at the beginning of any frame
exchange sequence where the MPDU is of type Data or Management, the
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MPDU has an individual address in the Address1 field, and the length
of the MPDU is greater than this threshold. Setting this attribute
to be larger than the maximum MSDU size MUST have the effect of
turning off the RTS/CTS handshake for frames of Data or Management
type transmitted by this STA. Setting this attribute to zero MUST
have the effect of turning on the RTS/CTS handshake for all frames of
Data or Management type transmitted by this STA. The default value
of this attribute MUST be 2347.
Short Retry: This attribute indicates the maximum number of
transmission attempts of a frame, the length of which is less than or
equal to RTSThreshold, that MUST be made before a failure condition
is indicated. The default value of this attribute MUST be 7.
Long Retry: This attribute indicates the maximum number of
transmission attempts of a frame, the length of which is greater than
dot11RTSThreshold, that MUST be made before a failure condition is
indicated. The default value of this attribute MUST be 4.
Fragmentation Threshold: This attribute specifies the current
maximum size, in octets, of the MPDU that MAY be delivered to the
PHY. An MSDU MUST be broken into fragments if its size exceeds the
value of this attribute after adding MAC headers and trailers. An
MSDU or MMPDU MUST be fragmented when the resulting frame has an
individual address in the Address1 field, and the length of the frame
is larger than this threshold. The default value for this attribute
MUST be the lesser of 2346 or the aMPDUMaxLength of the attached PHY
and MUST never exceed the lesser of 2346 or the aMPDUMaxLength of the
attached PHY. The value of this attribute MUST never be less than
256.
Tx MSDU Lifetime: This attribute speficies the elapsed time in TU,
after the initial transmission of an MSDU, after which further
attempts to transmit the MSDU MUST be terminated. The default value
of this attribute MUST be 512.
Rx MSDU Lifetime: This attribute specifies the elapsed time in TU,
after the initial reception of a fragmented MMPDU or MSDU, after
which further attempts to reassemble the MMPDU or MSDU MUST be
terminated. The default value MUST be 512.
B.1.4.5 Binding Tx Power Level
The Tx power level message element is sent by the AP and contains the
different power levels supported. The value contains the following
fields.
0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Num Levels | Power Level [n] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Num Levels: The number of power level attributes
Power Level: Each power level fields contains a supported power
level, in mW.
B.1.4.6 Binding Direct Sequence Control
The direct sequence control message element is a bi-directional
element. When sent by the AP, it contains the current state. When
sent by the AR, the AP MUST adhere to the values. This element is
only used for 802.11b radios. The value has the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Reserved | Current Chan | Current CCA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Energy Detect Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Reserved: MUST be set to zero
Current Channel: This attribute contains the current operating
frequency channel of the DSSS PHY.
Current CCA: The current CCA method in operation. Valid values are:
1 - energy detect only (edonly)
2 - carrier sense only (csonly)
4 - carrier sense and energy detect (edandcs)
8 - carrier sense with timer (cswithtimer)
16 - high rate carrier sense and energy detect (hrcsanded)
Energy Detect Threshold: The current Energy Detect Threshold being
used by the DSSS PHY
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B.1.4.7 Binding OFDM Control
The OFDM control message element is a bi-directional element. When
sent by the AP, it contains the current state. When sent by the AR,
the AP MUST adhere to the values. This element is only used for
802.11a radios. The value contains the following fields:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Reserved | Current Chan | Band Support |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TI Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Reserved: MUST be set to zero
Current Channel: This attribute contains the current operating
frequency channel of the OFDM PHY.
Band Supported: The capability of the OFDM PHY implementation to
operate in the three U-NII bands. Coded as an integer value of a
three bit field as follows:
capable of operating in the lower (5.15-5.25 GHz) U-NII band
capable of operating in the middle (5.25-5.35 GHz) U-NII band
capable of operating in the upper (5.725-5.825 GHz) U-NII band
For example, for an implementation capable of operating in the lower
and mid bands this attribute would take the value
TI Threshold: The Threshold being used to detect a busy medium
(frequency). CCA MUST report a busy medium upon detecting the RSSI
above this threshold
B.1.4.8 Binding Supported Rates
The supported rates message element is sent by the AP to indicate the
rates that it supports. The value contains the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Supported Rates |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Radio ID: An 8-bit value representing the radio
Supported Rates: The AP includes the Supported Rates that it's
hardware supports. The format is identical to the Rate Set message
element.
B.1.4.9 Binding Statistics
The statistics message element is sent by the AP to transmit it's
current statistics. The value contains the following fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Tx Fragment Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Tx Fragment Cnt| Multicast Tx Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mcast Tx Cnt | Failed Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Failed Count | Retry Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Retry Count | Multiple Retry Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Multi Retry Cnt| Frame Duplicate Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Dup Cnt | RTS Success Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RTS Success Cnt| RTS Failure Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RTS Failure Cnt| ACK Failure Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|ACK Failure Cnt| Rx Fragment Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Rx Fragment Cnt| Multicast RX Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mcast Rx Cnt | FCS Error Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCS Error Cnt| Tx Frame Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tx Frame Cnt | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio
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Tx Fragment Count: A 32-bit value representing the number of
fragmented frames transmitted.
Multicast Tx Count: A 32-bit value representing the number of
multicast frames transmitted.
Failed Count: A 32-bit value representing the transmit excessive
retries.
Retry Count: A 32-bit value representing the number of transmit
retries.
Multiple Retry Count: A 32-bit value representing the number of
transmits that required more than one retry.
Frame Duplicate Count: A 32-bit value representing the duplicate
frames received.
RTS Success Count: A 32-bit value representing the number of
successful Ready To Send (RTS).
RTS Failure Count: A 32-bit value representing the failed RTS.
ACK Failure Count: A 32-bit value representing the number of failed
acknowledgements.
Rx Fragment Count: A 32-bit value representing the number of
fragmented frames received.
Multicast RX Count: A 32-bit value representing the number of
multicast frames received.
FCS Error Count: A 32-bit value representing the number of FCS
failures.
Reserved: MUST be set to zero
B.1.4.10 Binding Antenna
The antenna message element is communicated by the AP to the AR to
provide information on the antennas available. The AR MAY use this
element to reconfigure the AP's antennas. The value contains the
following fields:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Diversity | Reserved | Antenna Cnt |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Antenna Selection [0..N] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio
Diversity: An 8-bit value specifying whether the antenna is to
provide receive diversity. The following values are supported:
Disabled
Enabled (may only be true if the antenna can be used as a receive
antenna)
Reserved: MUST be set to zero
Antenna Count: An 8-bit value specifying the number of Antenna
Selection fields.
The following values are supported:
Sectorized (Left)
Sectorized (Right)
Omni
B.1.4.11 Binding WLAN Payload
The WLAN payload message element is used by the AR to define a
wireless LAN on the AP. The value contains the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | WLAN Capability | WLAN ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| WLAN ID | SSID ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio
WLAN Capability: A 16-bit value containing the capabilities to be
advertised by the AP within the Probe and Beacon messages.
WLAN ID: A 16-bit value specifying the WLAN Identifier
SSID: The SSID attribute is a variable length byte string containing
the SSID to be advertised by the AP. The string is NOT zero
terminated.
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B.1.4.12 Binding Tx Power
The Tx power message element value is bi-directional. When sent by
the AP, it contains the current power level of the radio in question.
When sent by the AR, it contains the power level the AP MUST adhere
to.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Reserved | Current Tx Power |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio to configure
Reserved: MUST be set to zero
Current Tx Power: This attribute contains the transmit output power
in mW
B.1.4.13 Binding Mobile Session Key
The Mobile Session Key Payload message element is sent when the AR
determines that encryption of a mobile station must be performed in
the AP. This message element MUST NOT be present without the Add
Mobile (see Section 5.30) message element, and MUST NOT be sent if
the AP had not specifically advertised support for the requested
encryption scheme (see Section 5.3).
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address | Encryption Policy |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encryption Policy | Session Key... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MAC Address: The mobile station's MAC Address
Encryption Policy: The policy field informs the AP how to handle
packets from/to the mobile station. The following values are
supported:
Encrypt WEP 104: All packets to/from the mobile station must be
encrypted using standard 104 bit WEP.
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Clear Text: All packets to/from the mobile station do not require
any additional crypto processing by the AP.
Encrypt WEP 40: All packets to/from the mobile station must be
encrypted using standard 40 bit WEP.
Encrypt WEP 128: All packets to/from the mobile station must be
encrypted using standard 128 bit WEP.
Encrypt AES-OCB 128: All packets to/from the mobile station must
be encrypted using 128 bit AES OCB [11]
Encrypt TKIP-MIC: All packets to/from the mobile station must be
encrypted using TKIP and authenticated using Michael [9]
Session Key: The session key the AP is to use when encrypting
traffic to/from the mobile station.
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