tech-invite   World Map     

3GPP     Specs     Glossaries     Architecture     IMS     UICC       IETF     RFCs     Groups     SIP     ABNFs       Search

RFC 5412

 
 
 

Lightweight Access Point Protocol

Part 3 of 5, p. 39 to 66
Prev RFC Part       Next RFC Part

 


prevText      Top      Up      ToC       Page 39 
6.  Control Channel Management

   The Control Channel Management messages are used by the WTP and AC to
   create and maintain a channel of communication on which various other
   commands may be transmitted, such as configuration, firmware update,
   etc.

6.1.  Join Request

   The Join Request is used by a WTP to inform an AC that it wishes to
   provide services through it.

   Join Requests are sent by a WTP in the Joining state after receiving
   one or more Discovery Responses.  The Join Request is also used as an
   MTU discovery mechanism by the WTP.  The WTP issues a Join Request
   with a Test message element, bringing the total size of the message
   to exceed MTU.

Top      Up      ToC       Page 40 
   If the transport used does not provide MTU path discovery, the
   initial Join Request is padded with the Test message element to 1596
   bytes.  If a Join Response is received, the WTP can forward frames
   without requiring any fragmentation.  If no Join Response is
   received, it issues a second Join Request padded with the Test
   payload to a total of 1500 bytes.  The WTP continues to cycle from
   large (1596) to small (1500) packets until a Join Response has been
   received, or until both packets' sizes have been retransmitted 3
   times.  If the Join Response is not received after the maximum number
   of retransmissions, the WTP MUST abandon the AC and restart the
   discovery phase.

   When an AC receives a Join Request, it will respond with a Join
   Response.  If the certificate-based security mechanism is used, the
   AC validates the certificate found in the request.  If valid, the AC
   generates a session key that will be used to secure the control
   frames it exchanges with the WTP.  When the AC issues the Join
   Response, the AC creates a context for the session with the WTP.

   If the pre-shared session key security mechanism is used, the AC
   saves the WTP's nonce, found in the WNonce message element, and
   creates its own nonce, which it includes in the ANonce message
   element.  Finally, the AC creates the PSK-MIC, which is computed
   using a key that is derived from the PSK.

   A Join Request that includes both a WNonce and a Certificate message
   element MUST be considered invalid.

   Details on the key generation are found in Section 10.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.1.1.  WTP Descriptor

   The WTP Descriptor message element is defined in Section 5.1.2.

6.1.2.  AC Address

   The AC Address message element is defined in Section 5.2.1.

6.1.3.  WTP Name

   The WTP Name message element value is a variable-length byte string.
   The string is NOT zero terminated.

Top      Up      ToC       Page 41 
       0
       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      | Name ...
      +-+-+-+-+-+-+-+-+

   Type:   5 for WTP Name

   Length:   > 0

   Name:   A non-zero-terminated string containing the WTP's name.

6.1.4.  Location Data

   The Location Data message element is a variable-length byte string
   containing user-defined location information (e.g., "Next to
   Fridge").  The string is NOT zero terminated.

       0
       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      | Location ...
      +-+-+-+-+-+-+-+-+

   Type:   35 for Location Data

   Length:   > 0

   Location:   A non-zero-terminated string containing the WTP's
      location.

6.1.5.  WTP Radio Information

   A WTP Radio Information message element must be present for every
   radio in the WTP.  This message element is defined in Section 5.1.3.

6.1.6.  Certificate

   The Certificate message element value is a byte string containing a
   DER-encoded x.509v3 certificate.  This message element is only
   included if the LWAPP security type used between the WTP and the AC
   makes use of certificates (see Section 10 for more information).

       0
       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      | Certificate...
      +-+-+-+-+-+-+-+-+

Top      Up      ToC       Page 42 
   Type:   44 for Certificate

   Length:   > 0

   Certificate:   A non-zero-terminated string containing the device's
      certificate.

6.1.7.  Session ID

   The Session ID message element value contains a randomly generated
   [4] unsigned 32-bit integer.

       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                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   45 for Session ID

   Length:   4

   Session ID:   32-bit random session identifier.

6.1.8.  Test

   The Test message element is used as padding to perform MTU discovery,
   and it MAY contain any value, of any length.

       0
       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |  Padding ...
      +-+-+-+-+-+-+-+-+

   Type:   18 for Test

   Length:   > 0

   Padding:   A variable-length pad.

6.1.9.  XNonce

   The XNonce is used by the WTP to communicate its random nonce during
   the join or rekey phase.  See Section 10 for more information.

Top      Up      ToC       Page 43 
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   111 for XNonce

   Length:   16

   Nonce:   1 16-octet random nonce.

6.2.  Join Response

   The Join Response is sent by the AC to indicate to a WTP whether it
   is capable and willing to provide service to it.

   Join Responses are sent by the AC after receiving a Join Request.
   Once the Join Response has been sent, the Heartbeat timer is
   initiated for the session to EchoInterval.  Expiration of the timer
   will result in deletion of the AC-WTP session.  The timer is
   refreshed upon receipt of the Echo Request.

   If the security method used is certificate-based, when a WTP receives
   a Join Response, it enters the Joined state and initiates either a
   Configure Request or Image Data to the AC to which it is now joined.
   Upon entering the Joined state, the WTP begins timing an interval
   equal to NeighborDeadInterval.  Expiration of the timer will result
   in the transmission of the Echo Request.

   If the security method used is pre-shared-secret-based, when a WTP
   receives a Join Response that includes a valid PSK-MIC message
   element, it responds with a Join ACK that also MUST include a locally
   computed PSK-MIC message element.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

Top      Up      ToC       Page 44 
6.2.1.  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.  The Result Code is included in a
   successful Join Response.

       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                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   2 for Result Code

   Length:   4

   Result Code:   The following values are defined:

      0  Success

      1  Failure (AC List message element MUST be present)

6.2.2.  Status

   The Status message element is sent by the AC to the WTP in a non-
   successful Join Response message.  This message element is used to
   indicate the reason for the failure and should only be accompanied
   with a Result Code message element that indicates a failure.

       0
       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |    Status     |
      +-+-+-+-+-+-+-+-+

   Type:   60 for Status

   Length:   1

   Status:   The Status field indicates the reason for an LWAPP failure.
      The following values are supported:

Top      Up      ToC       Page 45 
      1 -  Reserved - do not use

      2 -  Resource Depletion

      3 -  Unknown Source

      4 -  Incorrect Data

6.2.3.  Certificate

   The Certificate message element is defined in Section 6.1.6.  Note
   this message element is only included if the WTP and the AC make use
   of certificate-based security as defined in Section 10.

6.2.4.  WTP Manager Data IPv4 Address

   The WTP Manager Data IPv4 Address message element is optionally sent
   by the AC to the WTP during the join phase.  If present, the IP
   Address contained in this message element is the address the WTP is
   to use when sending any of its LWAPP data frames.

   Note that this message element is only valid when LWAPP uses the
   IP/UDP Layer 3 transport.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           IP Address                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   138 for WTP Manager Data IPv4 Address

   Length:   4

   IP Address:   The IP address of an interface.

6.2.5.  WTP Manager Data IPv6 Address

   The WTP Manager Data IPv6 Address message element is optionally sent
   by the AC to the WTP during the join phase.  If present, the IP
   Address contained in this message element is the address the WTP is
   to use when sending any of its LWAPP data frames.

   Note that this message element is only valid when LWAPP uses the
   IP/UDP Layer 3 transport.

Top      Up      ToC       Page 46 
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           IP Address                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           IP Address                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           IP Address                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           IP Address                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   139 for WTP Manager Data IPv6 Address

   Length:   4

   IP Address:   The IP address of an interface.

6.2.6.  AC IPv4 List

   The AC List message element is used to configure a WTP with the
   latest list of ACs in a cluster.  This message element MUST be
   included if the Join Response returns a failure indicating that the
   AC cannot handle the WTP at this time, allowing the WTP to find an
   alternate AC to which to connect.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       AC IP Address[]                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   59 for AC List

   Length:   >= 4

   AC IP Address:   An array of 32-bit integers containing an AC's IPv4
      Address.

6.2.7.  AC IPv6 List

   The AC List message element is used to configure a WTP with the
   latest list of ACs in a cluster.  This message element MUST be
   included if the Join Response returns a failure indicating that the
   AC cannot handle the WTP at this time, allowing the WTP to find an
   alternate AC to which to connect.

Top      Up      ToC       Page 47 
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       AC IP Address[]                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       AC IP Address[]                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       AC IP Address[]                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       AC IP Address[]                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   141 for AC List

   Length:   >= 4

   AC IP Address:   An array of 32-bit integers containing an AC's IPv6
      Address.

6.2.8.  ANonce

   The ANonce message element is sent by an AC during the join or rekey
   phase.  The contents of the ANonce are encrypted as described in
   Section 10 for more information.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   108 for ANonce

   Length:   16

   Nonce:   An encrypted, 16-octet random nonce.

Top      Up      ToC       Page 48 
6.2.9.  PSK-MIC

   The PSK-MIC message element includes a message integrity check, whose
   purpose is to provide confirmation to the peer that the sender has
   the proper session key.  This message element is only included if the
   security method used between the WTP and the AC is the pre-shared
   secret mechanism.  See Section 10 for more information.

   When present, the PSK-MIC message element MUST be the last message
   element in the message.  The MIC is computed over the complete LWAPP
   packet, from the LWAPP control header as defined in Section 4.2.1 to
   the end of the packet (which MUST be this PSK-MIC message element).
   The MIC field in this message element and the Sequence Number field
   in the LWAPP control header MUST be set to zeroes prior to computing
   the MIC.  The length field in the LWAPP control header must already
   include this message element prior to computing the MIC.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       SPI       |                    MIC ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   109 for PSK-MIC

   Length:   > 1

   SPI:   The Security Parameter Index (SPI) field specifies the
      cryptographic algorithm used to create the message integrity
      check.  The following values are supported:

      0 -  Unused

      1 -  HMAC-SHA-1 (RFC 2104 [15])

   MIC:   A 20-octet Message Integrity Check.

6.3.  Join ACK

   The Join ACK message is sent by the WTP upon receiving a Join
   Response, which has a valid PSK-MIC message element, as a means of
   providing key confirmation to the AC.  The Join ACK is only used in
   the case where the WTP makes use of the pre-shared key LWAPP mode
   (see Section 10 for more information).

   Note that the AC should never receive this message unless the
   security method used between the WTP and the AC is pre-shared-secret-
   based.

Top      Up      ToC       Page 49 
   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.3.1.  Session ID

   The Session ID message element is defined in Section 6.1.7.

6.3.2.  WNonce

   The WNonce message element is sent by a WTP during the join or rekey
   phase.  The contents of the ANonce are encrypted as described in
   Section 10 for more information.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Nonce                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   107 for WNonce

   Length:   16

   Nonce:   An encrypted, 16-octet random nonce.

6.3.3.  PSK-MIC

   The PSK-MIC message element is defined in Section 6.2.9.

6.4.  Join Confirm

   The Join Confirm message is sent by the AC upon receiving a Join ACK,
   which has a valid PSK-MIC message element, as a means of providing
   key confirmation to the WTP.  The Join Confirm is only used in the
   case where the WTP makes use of the pre-shared key LWAPP mode (see
   Section 10 for more information).

   If the security method used is pre-shared-key-based, when a WTP
   receives a Join Confirm, it enters the Joined state and initiates
   either a Configure Request or Image Data to the AC to which it is now

Top      Up      ToC       Page 50 
   joined.  Upon entering the Joined state, the WTP begins timing an
   interval equal to NeighborDeadInterval.  Expiration of the timer will
   result in the transmission of the Echo Request.

   This message is never received, or sent, when the security type used
   between the WTP and the AC is certificated-based.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.4.1.  Session ID

   The Session ID message element is defined in Section 6.1.7.

6.4.2.  PSK-MIC

   The PSK-MIC message element is defined in Section 6.2.9.

6.5.  Echo Request

   The Echo Request message is a keepalive mechanism for the LWAPP
   control message.

   Echo Requests are sent periodically by a WTP in the Run state (see
   Figure 2) to determine the state of the connection between the WTP
   and the AC.  The Echo Request is sent by the WTP when the Heartbeat
   timer expires, and it MUST start its NeighborDeadInterval timer.

   The Echo Request carries no message elements.

   When an AC receives an Echo Request, it responds with an Echo
   Response.

6.6.  Echo Response

   The Echo Response acknowledges the Echo Request, and is only accepted
   while in the Run state (see Figure 2).

   Echo Responses are sent by an AC after receiving an Echo Request.
   After transmitting the Echo Response, the AC should reset its
   Heartbeat timer to expire in the value configured for EchoInterval.
   If another Echo request is not received by the AC when the timer
   expires, the AC SHOULD consider the WTP to no longer be reachable.

   The Echo Response carries no message elements.

Top      Up      ToC       Page 51 
   When a WTP receives an Echo Response it stops the
   NeighborDeadInterval timer, and starts the Heartbeat timer to
   EchoInterval.

   If the NeighborDeadInterval timer expires prior to receiving an Echo
   Response, the WTP enters the Idle state.

6.7.  Key Update Request

   The Key Update Request is used by the WTP to initiate the rekeying
   phase.  This message is sent by a WTP when in the Run state and MUST
   include a new unique Session Identifier.  This message MUST also
   include a unique nonce in the XNonce message element, which is used
   to protect against replay attacks (see Section 10).

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.7.1.  Session ID

   The Session ID message element is defined in Section 6.1.7.

6.7.2.  XNonce

   The XNonce message element is defined in Section 6.1.9.

6.8.  Key Update Response

   The Key Update Response is sent by the AC in response to the request
   message, and includes an encrypted ANonce, which is used to derive
   new session keys.  This message MUST include a Session Identifier
   message element, whose value MUST be identical to the one found in
   the Key Update Request.

   The AC MUST include a PSK-MIC message element, which provides message
   integrity over the whole message.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.8.1.  Session ID

   The Session ID message element is defined in Section 6.1.7.

6.8.2.  ANonce

   The ANonce message element is defined in Section 6.2.8.

Top      Up      ToC       Page 52 
6.8.3.  PSK-MIC

   The PSK-MIC message element is defined in Section 6.2.9.

6.9.  Key Update ACK

   The Key Update ACK is sent by the WTP and includes an encrypted
   version of the WTP's nonce, which is used in the key derivation
   process.  The session keys derived are then used as new LWAPP control
   message encryption keys (see Section 10).

   The WTP MUST include a PSK-MIC message element, which provides
   message integrity over the whole message.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.9.1.  WNonce

   The WNonce message element is defined in Section 6.3.2.

6.9.2.  PSK-MIC

   The PSK-MIC message element is defined in Section 6.2.9.

6.10.  Key Update Confirm

   The Key Update Confirm closes the rekeying loop, and allows the WTP
   to recognize that the AC has received and processed the Key Update
   messages.  At this point, the WTP updates its session key in its
   crypto engine, and the associated Initialization Vector, ensuring
   that all future LWAPP control frames are encrypted with the newly
   derived encryption key.

   The WTP MUST include a PSK-MIC message element, which provides
   message integrity over the whole message.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.10.1.  PSK-MIC

   The PSK-MIC message element is defined in Section 6.2.9.

6.11.  Key Update Trigger

   The Key Update Trigger is used by the AC to request that a Key Update
   Request be initiated by the WTP.

Top      Up      ToC       Page 53 
   Key Update Triggers are sent by an AC in the Run state to inform the
   WTP to initiate a Key Update Request message.

   When a WTP receives a Key Update Trigger, it generates a Key Update
   Request.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

6.11.1.  Session ID

   The Session ID message element is defined in Section 6.1.7.

7.  WTP Configuration Management

   The Wireless Termination Point Configuration messages are used to
   exchange configuration between the AC and the WTP.

7.1.  Configuration Consistency

   The LWAPP protocol provides flexibility in how WTP configuration is
   managed.  To put it simply, a WTP has one of two options:

   1. The WTP retains no configuration and simply abides by the
      configuration provided by the AC.

   2. The WTP retains the configuration of parameters provided by the AC
      that are non-default values.

   If the WTP opts to save configuration locally, the LWAPP protocol
   state machine defines the "Configure" state, which is used during the
   initial binding WTP-AC phase, which allows for configuration
   exchange.  During this period, the WTP sends its current
   configuration overrides to the AC via the Configure Request message.
   A configuration override is a parameter that is non-default.  One
   example is that in the LWAPP protocol, the default antenna
   configuration is an internal-omni antenna.  However, a WTP that
   either has no internal antennas, or has been explicitely configured
   by the AC to use external antennas would send its antenna
   configuration during the configure phase, allowing the AC to become
   aware of the WTP's current configuration.

   Once the WTP has provided its configuration to the AC, the AC sends
   down its own configuration.  This allows the WTP to inherit the
   configuration and policies on the AC.

Top      Up      ToC       Page 54 
   An LWAPP AC maintains a copy of each active WTP's configuration.
   There is no need for versioning or other means to identify
   configuration changes.  If a WTP becomes inactive, the AC MAY delete
   the configuration associated with it.  If a WTP were to fail, and
   connect to a new AC, it would provide its overridden configuration
   parameters, allowing the new AC to be aware of the WTP's
   configuration.

   As a consequence, this model allows for resiliency, whereby in light
   of an AC failure, another AC could provide service to the WTP.  In
   this scenario, the new AC would be automatically updated on any
   possible WTP configuration changes -- eliminating the need for Inter-
   AC communication or the need for all ACs to be aware of the
   configuration of all WTPs in the network.

   Once the LWAPP protocol enters the Run state, the WTPs begin to
   provide service.  However, it is quite common for administrators to
   require that configuration changes be made while the network is
   operational.  Therefore, the Configuration Update Request is sent by
   the AC to the WTP in order to make these changes at run-time.

7.2.  Configure Request

   The Configure Request message is sent by a WTP to send its current
   configuration to its AC.

   Configure Requests are sent by a WTP after receiving a Join Response,
   while in the Configure state.

   The Configure Request carries binding-specific message elements.
   Refer to the appropriate binding for the definition of this
   structure.

   When an AC receives a Configure Request, it will act upon the content
   of the packet and respond to the WTP with a Configure Response.

   The Configure Request includes multiple Administrative State message
   elements.  There is one such message element for the WTP, and then
   one per radio in the WTP.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

7.2.1.  Administrative State

   The Administrative Event message element is used to communicate the
   state of a particular radio.  The value contains the following
   fields.

Top      Up      ToC       Page 55 
       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Radio ID   |  Admin State  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   27 for Administrative State

   Length:   2

   Radio ID:   An 8-bit value representing the radio to configure.  The
      Radio ID field may also include the value of 0xff, which is used
      to identify the WTP itself.  Therefore, if an AC wishes to change
      the administrative state of a WTP, it would include 0xff in the
      Radio ID field.

   Admin State:   An 8-bit value representing the administrative state
      of the radio.  The following values are supported:

      1 -  Enabled

      2 -  Disabled

7.2.2.  AC Name

   The AC Name message element is defined in Section 5.2.3.

7.2.3.  AC Name with Index

   The AC Name with Index message element is sent by the AC to the WTP
   to configure preferred ACs.  The number of instances where this
   message element would be present is equal to the number of ACs
   configured on the WTP.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Index     |   AC Name...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   90 for AC Name with Index

   Length:   5

   Index:   The index of the preferred server (e.g., 1=primary,
      2=secondary).

   AC Name:   A variable-length ASCII string containing the AC's name.

Top      Up      ToC       Page 56 
7.2.4.  WTP Board Data

   The WTP Board Data message element is sent by the WTP to the AC and
   contains information about the hardware present.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Card ID            |         Card Revision         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          WTP Model                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          WTP Model                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      WTP Serial Number ...                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Reserved                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Ethernet MAC Address                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Ethernet MAC Address     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   50 for WTP Board Data

   Length:   26

   Card ID:   A hardware identifier.

   Card Revision:   4-byte Revision of the card.

   WTP Model:   8-byte WTP Model Number.

   WTP Serial Number:   24-byte WTP Serial Number.

   Reserved:   A 4-byte reserved field that MUST be set to zero (0).

   Ethernet MAC Address:   MAC address of the WTP's Ethernet interface.

7.2.5.  Statistics Timer

   The Statistics Timer message element value is used by the AC to
   inform the WTP of the frequency that it expects to receive updated
   statistics.

Top      Up      ToC       Page 57 
       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Statistics Timer       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   37 for Statistics Timer

   Length:   2

   Statistics Timer:   A 16-bit unsigned integer indicating the time, in
      seconds.

7.2.6.  WTP Static IP Address Information

   The WTP Static IP Address Information message element is used by an
   AC to configure or clear a previously configured static IP address on
   a WTP.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          IP Address                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Netmask                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Gateway                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Static     |
      +-+-+-+-+-+-+-+-+

   Type:   82 for WTP Static IP Address Information

   Length:   13

   IP Address:   The IP address to assign to the WTP.

   Netmask:   The IP Netmask.

   Gateway:   The IP address of the gateway.

   Netmask:   The IP Netmask.

   Static:   An 8-bit Boolean stating whether or not the WTP should use
      a static IP address.  A value of zero disables the static IP
      address, while a value of one enables it.

Top      Up      ToC       Page 58 
7.2.7.  WTP Reboot Statistics

   The WTP Reboot Statistics message element is sent by the WTP to the
   AC to communicate information about reasons why reboots have
   occurred.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Crash Count          |     LWAPP Initiated Count     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Link Failure Count       | Failure Type  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   67 for WTP Reboot Statistics

   Length:   7

   Crash Count:   The number of reboots that have occurred due to a WTP
      crash.

   LWAPP Initiated Count:   The number of reboots that have occurred at
      the request of some LWAPP message, such as a change in
      configuration that required a reboot or an explicit LWAPP reset
      request.

   Link Failure Count:   The number of times that an LWAPP connection
      with an AC has failed.

   Failure Type:   The last WTP failure.  The following values are
      supported:

      0 -  Link Failure

      1 -  LWAPP Initiated

      2 -  WTP Crash

7.3.  Configure Response

   The Configure Response message is sent by an AC and provides an
   opportunity for the AC to override a WTP's requested configuration.

   Configure Responses are sent by an AC after receiving a Configure
   Request.

Top      Up      ToC       Page 59 
   The Configure Response carries binding-specific message elements.
   Refer to the appropriate binding for the definition of this
   structure.

   When a WTP receives a Configure Response, it acts upon the content of
   the packet, as appropriate.  If the Configure Response message
   includes a Change State Event message element that causes a change in
   the operational state of one of the Radios, the WTP will transmit a
   Change State Event to the AC as an acknowledgement of the change in
   state.

   The following subsections define the message elements that MUST be
   included in this LWAPP operation.

7.3.1.  Decryption Error Report Period

   The Decryption Error Report Period message element value is used by
   the AC to inform the WTP of how frequently it should send decryption
   error report messages.

       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    |        Report Interval        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   38 for Decryption Error Report Period

   Length:   3

   Radio ID:   The Radio Identifier: typically refers to some interface
      index on the WTP.

   Report Interval:   A 16-bit, unsigned integer indicating the time, in
      seconds.

7.3.2.  Change State Event

   The WTP Radio Information message element is used to communicate the
   operational state of a radio.  The value contains two fields, as
   shown.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Radio ID    |     State     |     Cause     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Top      Up      ToC       Page 60 
   Type:   26 for Change State Event

   Length:   3

   Radio ID:   The Radio Identifier: typically refers to some interface
      index on the WTP.

   State:   An 8-bit Boolean value representing the state of the radio.
      A value of one disables the radio, while a value of two enables
      it.

   Cause:   In the event of a radio being inoperable, the Cause field
      would contain the reason the radio is out of service.  The
      following values are supported:

      0 -  Normal

      1 -  Radio Failure

      2 -  Software Failure

7.3.3.  LWAPP Timers

   The LWAPP Timers message element is used by an AC to configure LWAPP
   timers on a WTP.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Discovery   | Echo Request  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   68 for LWAPP Timers

   Length:   2

   Discovery:   The number of seconds between LWAPP Discovery packets
      when the WTP is in the discovery mode.

   Echo Request:   The number of seconds between WTP Echo Request LWAPP
      messages.

7.3.4.  AC IPv4 List

   The AC List message element is defined in Section 6.2.6.

Top      Up      ToC       Page 61 
7.3.5.  AC IPv6 List

   The AC List message element is defined in Section 6.2.7.

7.3.6.  WTP Fallback

   The WTP Fallback message element is sent by the AC to the WTP to
   enable or disable automatic LWAPP fallback in the event that a WTP
   detects its preferred AC, and is not currently connected to it.

       0
       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |     Mode      |
      +-+-+-+-+-+-+-+-+

   Type:   91 for WTP Fallback

   Length:   1

   Mode:   The 8-bit Boolean value indicates the status of automatic
      LWAPP fallback on the WTP.  A value of zero disables the fallback
      feature, while a value of one enables it.  When enabled, if the
      WTP detects that its primary AC is available, and it is not
      connected to it, it SHOULD automatically disconnect from its
      current AC and reconnect to its primary.  If disabled, the WTP
      will only reconnect to its primary through manual intervention
      (e.g., through the Reset Request command).

7.3.7.  Idle Timeout

   The Idle Timeout message element is sent by the AC to the WTP to
   provide it with the idle timeout that it should enforce on its active
   mobile station entries.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Timeout                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   97 for Idle Timeout

   Length:   4

   Timeout:   The current idle timeout to be enforced by the WTP.

Top      Up      ToC       Page 62 
7.4.  Configuration Update Request

   Configure Update Requests are sent by the AC to provision the WTP
   while in the Run state.  This is used to modify the configuration of
   the WTP while it is operational.

   When an AC receives a Configuration Update Request it will respond
   with a Configuration Update Response, with the appropriate Result
   Code.

   The following subsections define the message elements introduced by
   this LWAPP operation.

7.4.1.  WTP Name

   The WTP Name message element is defined in Section 6.1.3.

7.4.2.  Change State Event

   The Change State Event message element is defined in Section 7.3.2.

7.4.3.  Administrative State

   The Administrative State message element is defined in Section 7.2.1.

7.4.4.  Statistics Timer

   The Statistics Timer message element is defined in Section 7.2.5.

7.4.5.  Location Data

   The Location Data message element is defined in Section 6.1.4.

7.4.6.  Decryption Error Report Period

   The Decryption Error Report Period message element is defined in
   Section 7.3.1.

7.4.7.  AC IPv4 List

   The AC List message element is defined in Section 6.2.6.

7.4.8.  AC IPv6 List

   The AC List message element is defined in Section 6.2.7.

Top      Up      ToC       Page 63 
7.4.9.  Add Blacklist Entry

   The Add Blacklist Entry message element is used by an AC to add a
   blacklist entry on a WTP, ensuring that the WTP no longer provides
   any service to the MAC addresses provided in the message.  The MAC
   addresses provided in this message element are not expected to be
   saved in non-volative memory on the WTP.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Num of Entries|                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   65 for Add Blacklist Entry

   Length:   >= 7

   Num of Entries:   The number of MAC addresses in the array.

   MAC Address:   An array of MAC addresses to add to the blacklist
      entry.

7.4.10.  Delete Blacklist Entry

   The Delete Blacklist Entry message element is used by an AC to delete
   a previously added blacklist entry on a WTP, ensuring that the WTP
   provides service to the MAC addresses provided 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Num of Entries|                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   66 for Delete Blacklist Entry

   Length:   >= 7

   Num of Entries:   The number of MAC addresses in the array.

   MAC Address:   An array of MAC addresses to delete from the blacklist
      entry.

Top      Up      ToC       Page 64 
7.4.11.  Add Static Blacklist Entry

   The Add Static Blacklist Entry message element is used by an AC to
   add a permanent Blacklist Entry on a WTP, ensuring that the WTP no
   longer provides any service to the MAC addresses provided in the
   message.  The MAC addresses provided in this message element are
   expected to be saved in non-volative memory on the WTP.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Num of Entries|                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   70 for Delete Blacklist Entry

   Length:   >= 7

   Num of Entries:   The number of MAC addresses in the array.

   MAC Address:   An array of MAC addresses to add to the permanent
      blacklist entry.

7.4.12.  Delete Static Blacklist Entry

   The Delete Static Blacklist Entry message element is used by an AC to
   delete a previously added static blacklist entry on a WTP, ensuring
   that the WTP provides service to the MAC addresses provided 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Num of Entries|                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 MAC Address[]                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   71 for Delete Blacklist Entry

   Length:   >= 7

   Num of Entries:   The number of MAC addresses in the array.

   MAC Address:   An array of MAC addresses to delete from the static
      blacklist entry.

Top      Up      ToC       Page 65 
7.4.13.  LWAPP Timers

   The LWAPP Timers message element is defined in Section 7.3.3.

7.4.14.  AC Name with Index

   The AC Name with Index message element is defined in Section 7.2.3.

7.4.15.  WTP Fallback

   The WTP Fallback message element is defined in Section 7.3.6.

7.4.16.  Idle Timeout

   The Idle Timeout message element is defined in Section 7.3.7.

7.5.  Configuration Update Response

   The Configuration Update Response is the acknowledgement message for
   the Configuration Update Request.

   Configuration Update Responses are sent by a WTP after receiving a
   Configuration Update Request.

   When an AC receives a Configure Update Response, the result code
   indicates if the WTP successfully accepted the configuration.

   The following subsections define the message elements that must be
   present in this LWAPP operation.

7.5.1.  Result Code

   The Result Code message element is defined in Section 6.2.1.

7.6.  Change State Event Request

   The Change State Event is used by the WTP to inform the AC of a
   change in the operational state.

   The Change State Event message is sent by the WTP when it receives a
   Configuration Response that includes a Change State Event message
   element.  It is also sent in the event that the WTP detects an
   operational failure with a radio.  The Change State Event may be sent
   in either the Configure or Run state (see Figure 2).

   When an AC receives a Change State Event it will respond with a
   Change State Event Response and make any necessary modifications to
   internal WTP data structures.

Top      Up      ToC       Page 66 
   The following subsections define the message elements that must be
   present in this LWAPP operation.

7.6.1.  Change State Event

   The Change State Event message element is defined in Section 7.3.2.

7.7.  Change State Event Response

   The Change State Event Response acknowledges the Change State Event.

   Change State Event Responses are sent by a WTP after receiving a
   Change State Event.

   The Change State Event Response carries no message elements.  Its
   purpose is to acknowledge the receipt of the Change State Event.

   The WTP does not need to perform any special processing of the Change
   State Event Response message.

7.8.  Clear Config Indication

   The Clear Config Indication is used to reset a WTP's configuration.

   The Clear Config Indication is sent by an AC to request that a WTP
   reset its configuration to manufacturing defaults.  The Clear Config
   Indication message is sent while in the Run LWAPP state.

   The Reset Request carries no message elements.

   When a WTP receives a Clear Config Indication, it will reset its
   configuration to manufacturing defaults.



(page 66 continued on part 4)

Next RFC Part