PANA Working Group                                           D. Forsberg
Internet-Draft                                                     Nokia
Expires: September 4, 2006 February 23, 2007                                 Y. Ohba (Ed.)
                                                                 Toshiba
                                                                B. Patil
                                                                   Nokia
                                                           H. Tschofenig
                                                                 Siemens
                                                                A. Yegin
                                                                 Samsung
                                                           March 3,
                                                         August 22, 2006

     Protocol for Carrying Authentication for Network Access (PANA)
                        draft-ietf-pana-pana-11
                        draft-ietf-pana-pana-12

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Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document defines the Protocol for Carrying Authentication for
   Network Access (PANA), a link-layer agnostic transport for Extensible
   Authentication Protocol (EAP) to enable network access authentication
   between clients and access networks.  PANA protocol specification
   covers the client-to-network access authentication part of an overall
   secure network access framework, which additionally includes other
   protocols and mechanisms for service provisioning, access control as
   a result of initial authentication, and accounting.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.1.  Specification of Requirements  . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6  7
   3.  Protocol Overview  . . . . . . . . . . . . . . . . . . . . . .  8  9
   4.  Protocol Details . . . . . . . . . . . . . . . . . . . . . . . 10 11
     4.1.  Transport Layer  . . . . . . . . . . . . . . . . . . . . . 10 11
     4.2.   Payload Encoding  . . . . . .  High-Level Attribute-Value Pair Description  . . . . . . . 11
     4.3.  Handshake Phase  . . . . . . . 10
     4.3.   Discovery and Handshake Phase . . . . . . . . . . . . . . 11 12
     4.4.  Authentication and Authorization Phase . . . . . . . . . 15 . 14
     4.5.  Access Phase . . . . . . . . . . . . . . . . . . . . . . 18 . 17
     4.6.  Re-authentication Phase  . . . . . . . . . . . . . . . . . 19 18
     4.7.  Termination Phase  . . . . . . . . . . . . . . . . . . . . 20
     4.8.   Separate NAP and ISP Authentication . . . . . . . . . . . 21
       4.8.1.  Negotiating Separate NAP and ISP Authentication  . . . 21
       4.8.2.  Execution of Separate NAP and ISP Authentication . . . 22
       4.8.3.  AAA-Key Calculation  . . . . . . . . . . . . . . . . . 23 19
   5.  Processing Rules . . . . . . . . . . . . . . . . . . . . . . . 24 21
     5.1.  Fragmentation  . . . . . . . . . . . . . . . . . . . . . . 24 21
     5.2.  Sequence Number and Retransmission . . . . . . . . . . . 24 . 21
     5.3.  PANA Security Association  . . . . . . . . . . . . . . . . 25 22
     5.4.  Message Authentication . . . . . . . . . . . . . . . . . 27 . 24
     5.5.  Message Validity Check . . . . . . . . . . . . . . . . . 27 . 24
     5.6.  PaC-EP-Master-Key  . . . . . . . . . . . . . . . . . . . . 29 25
     5.7.  Device ID Choice . . . . . . . . . . . . . . . . . . . . 29 . 26
     5.8.  PaC Updating its IP Address  . . . . . . . . . . . . . . . 30 27
     5.9.  Session Lifetime . . . . . . . . . . . . . . . . . . . . 31 . 27
     5.10. Network Selection  . . . . . . . . . . . . . . . . . . . . 31 28
     5.11. Error Handling . . . . . . . . . . . . . . . . . . . . . 32 . 29
   6.  Header Format  . . . . . . . . . . . . . . . . . . . . . . . . 33 30
     6.1.  IP and UDP Headers . . . . . . . . . . . . . . . . . . . 33 . 30
     6.2.  PANA Header  . . . . . . . . . . . . . . . . . . . . . . . 33 30
     6.3.  AVP Header . . . . . . . . . . . . . . . . . . . . . . . 35 . 32
   7.  PANA Messages  . . . . . . . . . . . . . . . . . . . . . . . . 39 35
     7.1.   PANA-PAA-Discover (PDI) .  PANA-Client-Initiation (PCI) . . . . . . . . . . . . . . . . 41 37
     7.2.  PANA-Start-Request (PSR) . . . . . . . . . . . . . . . . 42 . 37
     7.3.  PANA-Start-Answer (PSA)  . . . . . . . . . . . . . . . . . 42 38
     7.4.  PANA-Auth-Request (PAR)  . . . . . . . . . . . . . . . . . 42 38
     7.5.  PANA-Auth-Answer (PAN) . . . . . . . . . . . . . . . . . 43 . 38
     7.6.  PANA-Reauth-Request (PRAR) . . . . . . . . . . . . . . . 43 . 39
     7.7.  PANA-Reauth-Answer (PRAA)  . . . . . . . . . . . . . . . . 43 39
     7.8.  PANA-Bind-Request (PBR)  . . . . . . . . . . . . . . . . . 43 39
     7.9.  PANA-Bind-Answer (PBA) . . . . . . . . . . . . . . . . . 44 . 40
     7.10. PANA-Ping-Request (PPR)  . . . . . . . . . . . . . . . . . 44 40
     7.11. PANA-Ping-Answer (PPA) . . . . . . . . . . . . . . . . . 44 . 40
     7.12. PANA-Termination-Request (PTR) . . . . . . . . . . . . . 45 . 40
     7.13. PANA-Termination-Answer (PTA)  . . . . . . . . . . . . . . 45 41
     7.14. PANA-Error-Request (PER) . . . . . . . . . . . . . . . . 45 . 41
     7.15. PANA-Error-Answer (PEA)  . . . . . . . . . . . . . . . . . 45 41
     7.16.  PANA-FirstAuth-End-Request (PFER) . . . . . . . . . . . . 46
     7.17.  PANA-FirstAuth-End-Answer (PFEA)  . . . . . . . . . . . . 46
     7.18. PANA-Update-Request (PUR)  . . . . . . . . . . . . . . . . 46
     7.19. 41
     7.17. PANA-Update-Answer (PUA) . . . . . . . . . . . . . . . . 46 . 42
   8.  AVPs in PANA . . . . . . . . . . . . . . . . . . . . . . . . . 48 43
     8.1.  Algorithm AVP  . . . . . . . . . . . . . . . . . . . . . . 50 45
     8.2.  AUTH AVP . . . . . . . . . . . . . . . . . . . . . . . . 50 . 45
     8.3.  Cookie AVP . . . . . . . . . . . . . . . . . . . . . . . 51 . 46
     8.4.  Device-Id AVP  . . . . . . . . . . . . . . . . . . . . . . 51 46
     8.5.  EAP-Payload AVP  . . . . . . . . . . . . . . . . . . . . . 51 46
     8.6.  Failed-AVP AVP . . . . . . . . . . . . . . . . . . . . . 51 . 46
     8.7.  ISP-Information AVP  . . . . . . . . . . . . . . . . . . . 51 46
     8.8.  Key-Id AVP . . . . . . . . . . . . . . . . . . . . . . . 52 . 47
     8.9.  NAP-Information AVP  . . . . . . . . . . . . . . . . . . . 52 47
     8.10. Nonce AVP  . . . . . . . . . . . . . . . . . . . . . . . . 52 47
     8.11. Notification AVP . . . . . . . . . . . . . . . . . . . . 53 . 48
     8.12. Post-PANA-Address-Configuration (PPAC) AVP . . . . . . . 53 . 48
     8.13. Protection-Capability AVP  . . . . . . . . . . . . . . . . 55 50
     8.14. Provider-Identifier AVP  . . . . . . . . . . . . . . . . . 55 50
     8.15. Provider-Name AVP  . . . . . . . . . . . . . . . . . . . . 55 50
     8.16. Result-Code AVP  . . . . . . . . . . . . . . . . . . . . . 55 50
       8.16.1.  Authentication Results Codes  . . . . . . . . . . . . . 55 50
       8.16.2.  Protocol Error Result Codes . . . . . . . . . . . . . 56 51
     8.17. Session-Id AVP . . . . . . . . . . . . . . . . . . . . . 58 . 53
     8.18. Session-Lifetime AVP . . . . . . . . . . . . . . . . . . 59 . 54
     8.19. Termination-Cause AVP  . . . . . . . . . . . . . . . . . . 59 54
   9.  Retransmission Timers  . . . . . . . . . . . . . . . . . . . . 60 55
     9.1.  Transmission and Retransmission Parameters . . . . . . . 61 . 56
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 63 58
     10.1. PANA UDP Port Number . . . . . . . . . . . . . . . . . . 63 . 58
     10.2. PANA Multicast Address  . . Header  . . . . . . . . . . . . . . . 63
     10.3.  PANA Header . . . . . . . . . . . . . . . . . . . . . . . 63
       10.3.1. 58
       10.2.1.  Message Type  . . . . . . . . . . . . . . . . . . . . . 63
       10.3.2. 58
       10.2.2.  Flags . . . . . . . . . . . . . . . . . . . . . . . . 64
     10.4. 59
     10.3. AVP Header . . . . . . . . . . . . . . . . . . . . . . . 64
       10.4.1. . 59
       10.3.1.  AVP Code  . . . . . . . . . . . . . . . . . . . . . . . 64
       10.4.2. 59
       10.3.2.  Flags . . . . . . . . . . . . . . . . . . . . . . . . 65
     10.5. 59
     10.4. AVP Values . . . . . . . . . . . . . . . . . . . . . . . 65
       10.5.1. . 60
       10.4.1.  Post-PANA-Address-Configuration AVP Values  . . . . . . 65
       10.5.2. 60
       10.4.2.  Protection-Capability AVP Values  . . . . . . . . . . . 65
       10.5.3. 60
       10.4.3.  Result-Code AVP Values  . . . . . . . . . . . . . . . . 65
       10.5.4. 60
       10.4.4.  Termination-Cause AVP Values  . . . . . . . . . . . . . 65 60
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 67 61
     11.1. General Security Measures  . . . . . . . . . . . . . . . . 67 61
     11.2.  Discovery Handshake  . . . . . . . . . . . . . . . . . . . . . . . . 68 62
     11.3. EAP Methods  . . . . . . . . . . . . . . . . . . . . . . . 69 63
     11.4.  Separate NAP and ISP Authentication . . . . . . . . . . . 69
     11.5. Cryptographic Keys . . . . . . . . . . . . . . . . . . . 69
     11.6. . 63
     11.5. Per-packet Ciphering . . . . . . . . . . . . . . . . . . 70
     11.7. . 64
     11.6. PAA-to-EP Communication  . . . . . . . . . . . . . . . . . 70
     11.8. 64
     11.7. Liveness Test  . . . . . . . . . . . . . . . . . . . . . . 71
     11.9. 64
     11.8. Updating PaC's IP Address  . . . . . . . . . . . . . . . . 71
     11.10. 65
     11.9. Early Termination of a Session . . . . . . . . . . . . . 71 . 65
   12. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 72 66
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 73 67
     13.1. Normative References . . . . . . . . . . . . . . . . . . 73 . 67
     13.2. Informative References . . . . . . . . . . . . . . . . . 74 . 68
   Appendix A.  Example Sequence of Separate NAP and ISP
                Authentication  . . . . .  IP Address Configuration  . . . . . . . . . . . . . . 76 70
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 78 73
   Intellectual Property and Copyright Statements . . . . . . . . . . 80 75

1.  Introduction

   Providing secure network access service requires access control based
   on the authentication and authorization of the clients and the access
   networks.  Client-to-network authentication provides parameters that
   are needed to police the traffic flow through the enforcement points.
   A protocol is needed to carry authentication methods between the
   client and the access network.

   Currently there is no standard network-layer solution for
   authenticating clients for network access.  Appendix A of [RFC4058]
   describes the problem statement that led to the development of PANA.

   Scope of this work is identified as designing a link-layer agnostic
   transport for network access authentication methods.  The Extensible
   Authentication Protocol (EAP) [RFC3748] provides such authentication
   methods.  In other words, PANA will carry EAP which can carry various
   authentication methods.  By the virtue of enabling transport of EAP
   above IP, any authentication method that can be carried as an EAP
   method is made available to PANA and hence to any link-layer
   technology.  There is a clear division of labor between PANA (an EAP
   lower layer), EAP and EAP methods as described in [RFC3748].

   Various environments and usage models for PANA are identified in
   Appendix A of [RFC4058].  Potential security threats for network-
   layer access authentication protocol are discussed in [RFC4016].
   These have been essential in defining the requirements [RFC4058] on
   the PANA protocol.  Note that some of these requirements are imposed
   by the chosen payload, EAP [RFC3748].

   There are components that are part of a complete secure network
   access solution but are outside of the PANA protocol specification,
   including IP address configuration, authentication method choice,
   filter rule installation, data traffic protection and protection, PAA-EP
   protocol. protocol
   and PAA discovery.  These components except for IP address
   configuration are described in separate documents (see
   [I-D.ietf-pana-framework] [I-D.ietf-
   pana-framework], [I-D.ietf-pana-snmp] and [I-D.ietf-pana-snmp]). [I-D.ietf-dhc-paa-option]).
   See Appendix A for the IP address configuration component.  The
   readers are recommended to go through the PANA Framework document [I-D.ietf-pana-
   framework]
   [I-D.ietf-pana-framework] prior to reading this protocol
   specification document.

1.1.  Specification of Requirements

   In this document, several words are used to signify the requirements
   of the specification.  These words are often capitalized.  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 [RFC2119].

2.  Terminology

   PANA Client (PaC):

      The client side of the protocol that resides in the access device
      (e.g., laptop, PDA, etc.).  It is responsible for providing the
      credentials in order to prove its identity (authentication) for
      network access authorization.  The PaC and the EAP peer are co-
      located in the same access device.

   PANA Authentication Agent (PAA):

      The protocol entity in the access network whose responsibility is
      to verify the credentials provided by a PANA client (PaC) and
      authorize network access to the device associated with the client
      and identified by a Device Identifier (DI).  The PAA and the EAP
      authenticator (and optionally the EAP server) are co-located in
      the same node.  Note the authentication and authorization
      procedure can, according to the EAP model, be also offloaded to
      the backend AAA infrastructure.

   PANA Session:

      A PANA session begins with the handshake between the PANA Client
      (PaC) and the PANA Authentication Agent (PAA), and terminates as a
      result of an authentication or liveness test failure, a message
      delivery failure after retransmissions reach maximum values,
      session lifetime expiration, or an explicit termination message.
      A fixed session identifier is maintained throughout a session.  A
      session cannot be shared across multiple network interfaces.  Only
      one device identifier of the PaC is allowed to be bound to a PANA
      session for simplicity.

   Session Lifetime:

      A duration that is associated with a PANA session.  For an
      established PANA session, the session lifetime is bound to the
      lifetime of the current authorization given to the PaC.  The
      session lifetime can be updated by a new round of EAP
      authentication before it expires.

   Session Identifier:

      This identifier is used to uniquely identify a PANA session on the
      PAA and PaC.  It includes an identifier of the PAA, therefore it
      cannot be shared across multiple PAAs.  It is included in PANA
      messages to bind the message to a specific PANA session.  This
      bidirectional identifier is allocated by the PAA following the
      handshake and freed when the session terminates.

   PANA Security Association (PANA SA):

      A PANA security association is formed between the PaC and the PAA
      by sharing cryptographic keying material and associated context.
      The formed duplex security association is used to protect the
      bidirectional PANA signaling traffic between the PaC and the PAA.

   Device Identifier (DI):

      The identifier used by the network as a handle to control and
      police the network access of a device.  Depending on the access
      technology, this identifier may contain an address that is carried
      in protocol headers (e.g., IP or link-layer address), or a locally
      significant identifier that is made available by the local
      protocol stack (e.g., circuit id, PPP interface id) of a connected
      device.

   Enforcement Point (EP):

      A node on the access network where per-packet enforcement policies
      (i.e., filters) are applied on the inbound and outbound traffic of
      access devices.  Information such as the DI and (optionally)
      cryptographic keys are provided by the PAA per client for
      generating filters on the EP.  The EP and PAA may be co-located.

   Network Access Provider (NAP):

      A service provider that provides physical and link-layer
      connectivity to an access network it manages.

   AAA-Key:

   MSK:

      A key derived by the EAP peer and EAP server and transported to
      the authenticator [I-D.ietf-eap-keying]. [RFC3748].

   For additional terminology definitions see the PANA framework
   document [I-D.ietf-pana-framework].

3.  Protocol Overview

   The PANA protocol is run between a client (PaC) and a server (PAA) in
   order to perform authentication and authorization for the network
   access service.

   The protocol messaging consists of a series of request and responses,
   some of which may be initiated by either end.  Each message can carry
   zero or more AVPs within the payload.  The main payload of PANA is
   EAP which performs authentication.  PANA helps the PaC and PAA
   establish an EAP session.

   PANA is a UDP-based protocol.  It has its own retransmission
   mechanism to reliably deliver messages.

   PANA messages are sent between the PaC and PAA as part of a PANA
   session.  A PANA session consists of distinct phases:

   o  Discovery and handshake  Handshake phase: This is the phase that initiates a new PANA
      session.  The handshake phase can be triggered by both the PaC discovers and
      the PAA(s) by either
      explicitly soliciting advertisements for them or receiving
      unsolicited advertisements.  The PaC's answer sent in response to
      an advertisement starts a new session. PAA.

   o  Authentication and authorization phase: Immediately following the
      discovery and
      handshake phase is the EAP execution between the PAA and PaC.  The
      EAP payload (which carry an EAP method inside) is what is used for
      authentication.  The PAA conveys the result of authentication and
      authorization to the PaC at the end of this phase.  This phase may involve execution of two EAP sessions back-
      to-back, one for the NAP and one for the ISP.

   o  Access phase: After a successful authentication and authorization
      the host gains access to the network and can send and receive IP
      data traffic through the EP(s).  At any time during this phase,
      the PaC and PAA may optionally send PANA ping messages to test
      liveness of the PANA session on the peer.

   o  Re-authentication phase: During the access phase, the PAA must
      initiate re-authentication before the PANA session lifetime
      expires.  EAP is carried by PANA to perform authentication.  This
      phase may be optionally triggered by both the PaC and the PAA
      without any respect to the session lifetime.  The session moves to
      this phase from the access phase, and returns back there upon
      successful re-authentication.

   o  Termination phase: The PaC or PAA may choose to discontinue the
      access service at any time.  An explicit disconnect message can be
      sent by either end.  If either the PaC or the PAA disconnects
      without engaging in termination messaging, it is expected that
      either the expiration of a finite session lifetime or failed
      liveness tests would clean up the session at the other end.

     PaC  PAA    Message
   -----------------------------------------------------
   // Discovery and handshake Handshake phase
      ----->     PANA-PAA-Discover     PANA-Client-Initiation
      <-----     PANA-Start-Request
      ----->     PANA-Start-Answer

   // Authentication and authorization phase
      <-----     PANA-Auth-Request /* EAP Request */
      ----->     PANA-Auth-Answer
      ----->     PANA-Auth-Request /* EAP Response */
      <-----     PANA-Auth-Answer
      <-----     PANA-Bind-Request /* EAP Success */
      ----->     PANA-Bind-Answer

   // Access phase (IP data traffic allowed)
      <-----     PANA-Ping-Request
      ----->     PANA-Ping-Answer

   // Termination phase
      ----->     PANA-Termination-Request
      <-----     PANA-Termination-Answer

   Figure 1: Illustration of PANA messages in a session

   Note that depending on the environment and deployment the protocol
   flow depicted in Figure 1 can be abbreviated (An unsolicited PANA-
   Start-Request message can be sent without a triggering PANA-PAA-Discover, PANA-Client-Initiation, EAP
   responses can be piggybacked on the PANA-Auth-Answers, and PANA-Ping
   and PANA-Termination usage is optional).

   Cryptographic protection of messages between the PaC and PAA is
   possible as soon as EAP in conjunction with the EAP method exports a
   shared key.  That shared key is used to create a PANA SA.  The PANA
   SA helps generate per-message authentication codes that provide
   integrity protection and authentication.

   Throughout the lifetime of a session, various problems found with the
   incoming messages can generate a PANA error message sent in response.

4.  Protocol Details

   The following sections explain in detail the various phases of a PANA
   session.

4.1.  Transport Layer

   PANA uses UDP as its transport layer protocol.  The UDP port number
   is To Be Assigned by IANA.  All messages except for PANA-PAA-Discover are always unicast.  The PANA-PAA-Discover message MAY be unicast
   when the PaC knows the IP address of the PAA.

4.2.  Payload Encoding  High-Level Attribute-Value Pair Description

   The payload of any PANA message consists of zero or more AVPs
   (Attribute Value Pairs).  The subsequent sections refer to these
   AVPs, therefore the list of AVPs are provided with a brief
   description before more extensive descriptions are included later in
   the document (see Section 8).

   o  Algorithm AVP: contains a pseudo-random function and an integrity
      algorithm.

   o  AUTH AVP: contains a Message Authentication Code that integrity
      protects the PANA message.

   o  Cookie AVP: contains a random value that is generated by the PAA
      according to [RFC4086] and used for making PAA discovery the handshake phase
      robust against blind resource consumption DoS attacks.

   o  Device-Id AVP: contains a device identifier (link-layer address or
      an IP address) of the PaC or an EP.

   o  EAP AVP: contains an EAP PDU.

   o  Failed-AVP: contains an offending AVP that caused a failure.

   o  Key-Id AVP: contains a AAA-Key an MSK identifier.

   o  Protection-Capability AVP: contains the type of per-packet
      protection (link-layer vs. network-layer) when a cryptographic
      mechanism should be enabled after PANA authentication.

   o  NAP-Information AVP, ISP-Information AVP: contains the identifier
      of a NAP and an ISP, respectively.

   o  Nonce AVP: contains a randomly chosen value [RFC4086] that is used
      in cryptographic key computations.

   o  Notification AVP: contains a displayable message.

   o  Provider-Identifier AVP: contains the identifier of a NAP or an
      ISP.

   o  PPAC AVP: Post-PANA-Address-Configuration AVP.  Used to indicate
      the available/chosen IP address configuration methods that can be
      used by the PaC after successful PANA authentication.

   o  Provider-Name AVP: contains a name of a NAP or an ISP.

   o  Result-Code AVP: contains information about the protocol execution
      results.

   o  Session-Id AVP: contains the PANA session identifier value.

   o  Session-Lifetime AVP: contains the duration of authorized access.

   o  Termination-Cause AVP: contains the reason of session termination.

4.3.  Discovery and  Handshake Phase

   When

   The handshake phase can be initiated by either the PaC knows or the IP address of the PAA, it can send a unicast
   PANA-PAA-Discover message and initiate the PANA exchange.  In other
   cases, PAA.

   PaC-initiated Handshake:

      When the PaC MUST rely on dynamic discovery methods, such as
   multicast-based and a traffic-driven discovery.

   Multicast-based Discovery:

      The PaCs and PAAs MUST implement multicast-based discovery where initiates the PaC handshake phase, it sends a PANA-PAA-Discover PANA-
      Client-Initiation message to a well-known
      administratively scoped multicast address (To Be Assigned by IANA)
      and UDP port (To Be Assigned by IANA).

      The network administrator MUST configure the multicast scope such
      that PAA.  When the discovery messages can reach only PaC is not
      configured with an IP address of the designated PAA(s).
      In case PAA before initiating the PAA(s)
      handshake phase, DHCP [I-D.ietf-dhc-paa-option] is on the same link used as the PaC,
      default method for dynamically configuring the
      administratively scoped multicast messages MUST not be forwarded
      by IP address of the routers.  Details
      PAA.  Alternative methods for dynamically discoverying the IP
      address of scope configuration the PAA may be used for PaC-initiated handshake but
      they are discussed in
      [RFC2365]. outside the scope of this specification.  The PAA(s) PAA that receive
      receives the discovery PANA-Client-Initiation message MUST respond with a
      unicast
      PANA-Start-Request message sent to the soliciting PaC.

   Traffic-driven Discovery:

      Alternatively,

   PAA-initiated Handshake:

      When the PaC MAY also choose to start sending data
      packets before getting authenticated.  The EP in an access network
      that implements PANA SHOULD drop such unauthorized packets upon
      receipt.  Additionally, PAA knows the EP MAY also take this traffic as an
      indication IP address of unauthorized PaC and notify the PAA.  The EP-to-PAA
      notification SHOULD be sent via [I-D.ietf-pana-snmp].  In
      response, the PAA SHOULD PaC, it MAY send an
      unsolicited PANA-Start-Request
      message to the PaC.  This is called traffic-driven  The details of how PAA discovery
      (an alternative to
      can learn the PaC explicitly soliciting for a PAA).
      Deployment IP address of this alternate scheme is optional.

   Other Alternatives:

      The EP-to-PAA notification MAY also be generated in response to
      receiving a link-up event notification on the EP [I-D.ietf-dna-
      link-information].

      Alternative PAA discovery schemes may be designed (e.g., DHCP-
      based) but they PaC are outside the scope of this specification.
      specificaiton.

   When the PaC receives a PANA-Start-Request message from a PAA, it
   responds with a PANA-Start-Answer message if it wishes to enter the
   authentication and authorization phase.

   There can be multiple PAAs in the access network and the PaC may
   receive multiple PANA-Start-Request messages from those PAAs.  The
   authentication and authorization result does not depend on which PAA
   is chosen by the PaC.  By default the PaC MAY choose the PAA that
   sent the first PANA-Start-Request message.

   A

   A PANA-Start-Request message MAY carry a Cookie AVP that contains a
   random value generated by the PAA.  The random value is referred to
   as a cookie.  The cookie is used for preventing the PAA from resource
   consumption DoS attacks by blind attackers which bombard the PAA with
   PANA-PAA-Discover
   PANA-Client-Initiation messages.  By relying on a cookie mechanism
   the PAA can avoid per-PaC state creation until after the PaC can
   produce the same cookie in its PANA-Start-Answer message.  In order
   to do that, the cookie MUST be computed in such a way that it does
   not require any per-session state maintenance on the PAA in order to
   verify the cookie returned in the PANA-Start-Answer message.  The PAA discovery
   handshake phase that takes advantage of cookies is called "stateless PAA discovery".
   handshake".  The exact algorithms and syntax used by the PAA to
   generate cookies does not affect interoperability and hence is not
   specified here.  Additionally, the PAA MAY limit the rate it
   processes incoming PANA-
   PAA-Discover PANA-Client-Initiation messages.

   When the PaC sends a PANA-Start-Answer message in response to a PANA-
   Start-Request containing a Cookie AVP, the answer MUST contain a
   Cookie AVP with the cookie value copied from the request.

   When the PAA receives the PANA-Start-Answer message from the PaC, it
   verifies the cookie.  The cookie is considered as valid if the
   received cookie matches the send cookie.  If the match is verified,
   the protocol enters the authentication and authorization phase.
   Otherwise, the PAA MUST silently discard the received message.

   The initial EAP Request message MAY be optionally carried by the
   PANA-Start-Request (as opposed to by a later PANA-Auth-Request)
   message in order to reduce the number of round-trips.  This
   optimization SHOULD NOT be used if the PAA discovery is desired to be stateless
   in the handshake phase since transmission of an EAP Request message
   creates a state at EAP layer.  See [RFC4137] for more information on
   the EAP state machine and the allocation of state information in the
   respective protocol steps.

   A Protection-Capability AVP, an Algorithm AVP and a Post-PANA-
   Address-Configuration (PPAC) AVP MAY be included in the PANA-Start-
   Request in order to indicate required and available capabilities for
   the network access.  These AVPs MAY be used by the PaC for assessing
   the capability match even before the authentication takes place.
   Since these AVPs are provided during the insecure discovery and handshake phase,
   there are certain security risks involved in using the provided
   information.  See Section 11 for further discussion on this.

   If the initial EAP Request message is carried in the PANA-Start-
   Request message, an EAP Response message MUST be carried in the PANA-
   Start-Answer message returned to the PAA.

   The PANA-Start-Request/Answer exchange is needed before entering the
   authentication and authorization phase even when the PaC is pre-
   configured with the IP address of the PAA and the PANA-PAA-Discover
   message is unicast.

   A Nonce AVP MUST be included in the first PANA-Auth-Request and PANA-
   Auth-Answer messages in the authentication and authorization phase
   when stateless PAA discovery handshake is used, and in PANA-Start-Request and
   PANA-Start-Answer PANA-
   Start-Answer messages in this phase otherwise.

   A PANA-Start-Request message in stateless PAA discovery handshake MUST NOT be
   retransmitted as this voids the statelessness on the PAA.  Instead,
   the PaC MUST retransmit the PANA-PAA-Discover PANA-Client-Initiation message until it
   receives a PANA-Start-Request message, and retransmit the PANA-Start-
   Answer message until it receives a PANA-Auth-Request message.  The
   PaC can determine whether the PAA is using stateless PAA discovery handshake by
   looking at the L-flag in the PANA header.  The PANA-Start-Request
   message MUST be retransmitted instead of the PANA-Start-Answer
   message when stateful PAA discovery handshake is used (L-flag is not set).

   It is possible that both the PAA and the PaC initiate the discovery
   and handshake
   procedure at the same time, i.e., the PAA sends a PANA-
   Start-Request PANA-Start-Request
   message while the PaC sends a PANA-PAA-Discover PANA-Client-Initiation message.  To
   resolve the race condition, the PAA SHOULD silently discard the PANA-PAA-Discover PANA-
   Client-Initiation message received from the PaC after it has sent a
   PANA-Start-Request message with creating a state (i.e., L-flag is not
   set) for the PaC.  In this case the PAA will retransmit the PANA-Start-Request PANA-
   Start-Request message based on a timer, if the PaC doesn't respond in
   time (the message was lost for example).  If the PAA had sent a PANA-Start-Request PANA-
   Start-Request message without creating a state for the PaC (i.e.,
   L-flag is set), then it SHOULD answer to the PANA-PAA-
   Discover PANA-Client-Initiation
   message.

   Figure 2 shows an example sequence for the discovery and handshake
   phase when a PANA-PAA-Discover message is sent by the PaC.  Figure 3
   shows an example sequence for the discovery and handshake phase with
   traffic-driven PAA discovery. PaC-initiated handshake.

      PaC      PAA         Message(sequence number)[AVPs]
      ------------------------------------------------------
         ----->            PANA-PAA-Discover(0)            PANA-Client-Initiation(0)
         <-----            PANA-Start-Request(x)[Cookie]
         ----->            PANA-Start-Answer(x)[Cookie]
                           (continued to the authentication and
                            authorization phase)

   Figure 2: Example sequence for the discovery and handshake phase when
   PANA-PAA-Discover is sent by the PaC

      PaC   EP      PAA    Message(sequence number)[AVPs]
      ------------------------------------------------------
       ---->o              (Data packet arrival or L2 trigger)
             ------>       PAA-to-EP protocol, or another mechanism
       <------------       PANA-Start-Request(x)[Cookie]
       ------------>       PANA-Start-Answer(x)[Cookie]
                           (continued to the authentication and
                            authorization phase)

   Figure 3: Example sequence for the discovery and PaC-initiated handshake phase with
   traffic-driven PAA discovery

4.4.  Authentication and Authorization Phase

   The main task of the authentication and authorization phase is to
   carry EAP messages between the PaC and the PAA.  EAP Request and
   Response messages are carried in PANA-Auth-Request messages.  PANA-
   Auth-Answer messages are simply used to acknowledge receipt of the
   requests.  As an optimization, a PANA-Auth-Answer message MAY include
   the EAP Response message.  This optimization MAY not be used when it
   takes time to generate the EAP Response message (due to, e.g.,
   intervention of human input), in which case returning an EAP-Auth-
   Answer message without piggybacking an EAP Response message can avoid
   unnecessary retransmission of the PANA-Auth-Request message.  Another
   optimization allows optionally carrying the first EAP Request/
   Response message in PANA-Start-Request/Answer message as described in
   Section 4.3.

   When stateless PAA discovery handshake was performed in the discovery and handshake phase, a
   Nonce AVP MUST be included in the first PANA-Auth-
   Request PANA-Auth-Request and PANA-Auth-Answer PANA-
   Auth-Answer messages.

   PANA allows execution of two separate authentication methods, one
   with NAP and one with ISP under the same PANA session.  This optional
   feature may be offered by the PAA and accepted by the PaC.  When
   performed separately, the result of the first EAP authentication is
   signaled via PANA-FirstAuth-End-Request and PANA-FirstAuth-End-Answer
   message exchange which delineates the first method execution from the
   next.  See Section 4.8 for a detailed discussion on separate NAP and
   ISP authentication.

   The result of PANA authentication is carried in a PANA-Bind-Request
   message sent from the PAA to the PaC.  This message carries the final EAP
   authentication result (whether it is the second EAP
   authentication result of NAP and ISP separate authentication, or the
   sole EAP authentication result) and and the result of PANA authentication.  The
   PANA-Bind-Request message MUST be acknowledged with a PANA-Bind-Answer PANA-Bind-
   Answer (PBA) message.  Figure 4 3 shows an example sequence in the
   authentication and authorization phase (no separate
   authentication). phase.

   PaC      PAA  Message(sequence number)[AVPs]
   --------------------------------------------------------------------
                 (continued from the discovery and handshake phase)
      <-----     PANA-Auth-Request(x+1)
                    [Session-Id, Nonce, EAP{Request}]
      ----->     PANA-Auth-Answer(x+1) // No piggybacking EAP Response
                    [Session-Id, Nonce]
      ----->     PANA-Auth-Request(y)
                    [Session-Id, EAP{Response}]
      <-----     PANA-Auth-Answer(y)
                    [Session-Id]
      <-----     PANA-Auth-Request(x+2)
                    [Session-Id, EAP{Request}]
      ----->     PANA-Auth-Answer(x+2) // Piggybacking EAP Response
                    [Session-Id, EAP{Response}]
      <-----     PANA-Bind-Request(x+3)
                    [Session-Id, Result-Code, EAP{Success}, Device-Id,
                     Key-Id, Algorithm,
                     Lifetime, Protection-Cap., PPAC, AUTH]
      ----->     PANA-Bind-Answer(x+3)
                    [Session-Id, Device-Id, Key-Id, PPAC, AUTH]

   Figure 4: 3: Example sequence for the authentication and authorization
   phase

   When an EAP method that is capable of deriving keys is used during
   the authentication and authorization phase and the keys are
   successfully derived, the PANA message that carries the EAP Success
   message (i.e., a PANA-FirstAuth-End-Request or a PANA-Bind-Request message) MUST contain a Key-Id AVP
   and an AUTH AVP, and an Algorithm AVP for the first derivation of
   keys in the session, and any subsequent message MUST contain an AUTH
   AVP.  An Algorithm AVP MUST NOT be contained in a PANA-FirstAuth-End-Request or a PANA-Bind-
   Request PANA-Bind-Request
   message after the first derivation of keys in the session.

   The PANA-Bind-Request and the PANA-Bind-Answer message exchange is
   also used for binding device identifiers of the PaC and EP(s) to the
   PANA SA.  To achieve this, if a Protection-Capability AVP is included
   in the PANA-Bind-Request message, the message MUST contain the device
   identifier in a Device-Id AVP for each EP.  Otherwise, if a
   Protection-Capability AVP is not included in the PANA-Bind-Request
   message, the message MUST contain the device identifier in a
   Device-Id AVP for each EP when a link-layer or IP address is used as
   the device identifier of the PaC.  The PANA-Bind-Answer message MUST
   contain the PaC's device identifier in a Device-Id AVP when it is
   already presented with that of EP(s) in the request with using the
   same type of device identifier as contained in the request.  If the
   PANA-Bind-Answer message sent from the PaC does not contain a
   Device-Id AVP with the same device identifier type contained in the
   request, the PAA sends a PANA-Error-Request message with a
   PANA_MISSING_AVP result code, and wait for a PANA-Error-Answer
   message to terminate the session.

   The PANA-Bind-Request message with a PANA_SUCCESS result code MUST
   also contain a Protection-Capability AVP if link-layer or network-
   layer ciphering is enabled after the authentication and authorization
   phase.  The PANA-Bind-Request message MAY also contain a Protection-
   Capability AVP to indicate if link-layer or network-layer ciphering
   should be enabled after the authentication and authorization phase.
   No link-layer or network-layer specific information is included in
   the Protection-Capability AVP.  It is assumed that the PAA is aware
   of the security capabilities of the access network.  The PANA
   protocol does not specify how the PANA SA and the Protection-
   Capability AVP will be used to provide per-packet protection for data
   traffic.  When the PaC does not support the protection capability
   indicated in the Protection-Capability AVP, the PaC MUST send a PANA-
   Error-Request message with a PANA_PROTECTION_CAPABILITY_UNSUPPORTED
   result code and terminate the PANA session.

   Additionally, the PANA-Bind-Request message with a PANA_SUCCESS
   result code MUST include a Post-PANA-Address-Configuration (PPAC)
   AVP, which helps the PAA to inform the PaC about whether a new IP
   address MUST be configured and the available methods to do so.  In
   this case, the PaC MUST include a PPAC AVP in the PANA-Bind-Answer
   message in order to indicate its choice of method when there is a
   match between the methods offered by the PAA and the methods
   available on the PaC.  When there is no match, the PaC MUST send a
   PANA-Error-Request message with a PANA_PPAC_CAPABILITY_UNSUPPORTED
   result code and terminate the PANA session.

   EAP authentication can fail at a pass-through authenticator without
   sending an EAP Failure message [RFC4137].  When this occurs, the PAA
   SHOULD send a PANA-Error-Request message to the PaC with using
   PANA_UNABLE_TO_COMPLY result code.  The PaC MUST NOT change its state
   unless the error message is secured by PANA or lower-layer.  In any
   case, a more appropriate way is to rely on a timeout on the PaC.

   There is a case where EAP authentication succeeds with producing an
   EAP Success message but network access authorization fails due to,
   e.g., authorization rejected by a AAA or authorization locally
   rejected by the PAA.  When this occurs, the PAA MUST send a PANA-
   Bind-Request with a result code PANA_AUTHORIZATION_REJECTED.  If a
   AAA-Key an
   MSK is established between the PaC and the PAA by the time when the
   EAP Success message is generated by the EAP server (this is the case
   when the EAP method provides protected success indication), the
   PANA-Bind-Request PANA-
   Bind-Request and PANA-Bind-Answer messages MUST be protected with an
   AUTH AVP and carry a Key-Id AVP.  The PANA-Bind-Request message MUST
   also carry an Algorithm AVP if it is for the first derivation of keys
   in the session.  The AAA-Key MSK and the PANA session MUST be deleted
   immediately after the PANA-Bind message exchange.

4.5.  Access Phase

   Once the authentication and authorization phase or the re-
   authentication phase successfully completes, the PaC gains access to
   the network and can send and receive IP data traffic through the
   EP(s) and the PANA session enters the access phase.  In this phase,
   PANA-Ping-Request and PANA-Ping-Answer messages can be used for
   testing the liveness of the PANA session on the PANA peer.  Both the
   PaC and the PAA are allowed to send a PANA-Ping-Request message to
   the communicating peer whenever they need to make sure the
   availability of the session on the peer and expect the peer to return
   a PANA-Ping-Answer message.  Both PANA-Ping-Request and PANA-Ping-
   Answer messages MUST be protected with an AUTH AVP when a PANA SA is
   available.

   Implementations MUST limit the rate of performing this test.  The PaC
   and the PAA can handle rate limitation on their own, they do not have
   to perform any coordination with each other.  There is no negotiation
   of timers for this purpose.  Additionally, an implementation MAY
   rate-limit processing the incoming PANA-Ping-Requests.

   Figure 5 4 and Figure 6 5 show liveness tests as they are initiated by
   the PaC and the PAA respectively.

   PaC      PAA     Message(sequence number)[AVPs]
   ------------------------------------------------------
      ----->        PANA-Ping-Request(q)[Session-Id, AUTH]
      <-----        PANA-Ping-Answer(q)[Session-Id, AUTH]

   Figure 5: 4: Example sequence for PaC-initiated liveness test

   PaC      PAA     Message(sequence number)[AVPs]
   ------------------------------------------------------
      <-----        PANA-Ping-Request(p)[Session-Id, AUTH]
      ----->        PANA-Ping-Answer(p)[Session-Id, AUTH]

   Figure 6: 5: Example sequence for PAA-initiated liveness test

4.6.  Re-authentication Phase

   The PANA session in the access phase can enter the re-authentication
   phase to extend the current session lifetime by re-executing EAP.
   Once the re-authentication phase successfully completes, the session
   re-enters the access phase.  Otherwise, the session is deleted.

   When the PaC wants to initiate re-authentication, it sends a PANA-
   Reauth-Request message to the PAA.  This message MUST contain a
   Session-Id AVP which is used for identifying the PANA session on the
   PAA.  If the PAA already has an established PANA session for the PaC
   with the matching session identifier, it MUST first respond with a
   PANA-Reauth-Answer message, followed by a PANA-Auth-Request that
   starts a new EAP authentication.  If the PAA cannot identify the
   session, it MAY respond with a PANA-Error-Request message with a
   result code PANA_UNKNOWN_SESSION_ID.  Transmission of this error
   request is made optional in case this behavior is leveraged for a DoS
   attack on the PAA.

   The PaC may receive a PANA-Auth-Request before receiving the answer
   to its outstanding PANA-Reauth-Request.  This condition can arise due
   to packet re-ordering or a race condition between the PaC and PAA
   when they both attempt to engage in re-authentication.  The PaC MUST
   keep discarding the received PANA-Auth-Requests until it receives the
   answer to its request.

   When the PAA initiates re-authentication, it sends a PANA-Auth-
   Request message containing the session identifier for the PaC to
   enter the re-authentication phase.  The PAA SHOULD initiate EAP re-
   authentication before the current session lifetime expires.

   Re-authentication of an on-going PANA session MUST maintain the
   existing sequence numbers.

   For any re-authentication, if there is an established PANA SA, PANA-
   Auth-Request and PANA-Auth-Answer messages MUST be protected by
   adding a MAC AVP to each message.  Any  If a network selection (see
   Section 5.10 was made during the handshake phase, any subsequent EAP
   authentication MUST be performed with the same ISP and NAP that was already selected during
   the discovery and handshake phase.  The value of the S-flag
   ("separate authentication" flag, see Section 4.8.1) of the PANA
   messages exchanged in the re-authentication phase MUST be inherited
   from the previous authentication ISP and authorization phase or re-
   authentication phase.
   NAP.

   PaC      PAA  Message(sequence number)[AVPs]
   ------------------------------------------------------
      ----->     PANA-Reauth-Request(q)
                    [Session-Id, AUTH]
      <-----     PANA-Reauth-Answer(q)
                    [Session-Id, AUTH]
      <-----     PANA-Auth-Request(p)
                    [Session-Id, EAP{Request}, AUTH]
      ----->     PANA-Auth-Answer(p)   // No piggybacking EAP Response
                    [Session-Id, AUTH]
      ----->     PANA-Auth-Request(q+1)
                    [Session-Id, EAP{Response}, AUTH]
      <-----     PANA-Auth-Answer(q+1) // No piggybacking EAP Response
                    [Session-Id, AUTH]
      <-----     PANA-Auth-Request(p+1)
                    [Session-Id, EAP{Request}, AUTH]
      ----->     PANA-Auth-Answer(p+1) // Piggybacking EAP Response
                    [Session-Id, EAP{Response}, AUTH]
      <-----     PANA-Bind-Request(p+2)
                    [Session-Id, Result-Code, EAP{Success},
                     Device-Id, Key-Id, Algorithm,
                     Lifetime, Protection-Cap., PPAC, AUTH]
      ----->     PANA-Bind-Answer(p+2)
                    [Session-Id, Device-Id, Key-Id, PPAC, AUTH]

   Figure 7: 6: Example sequence for the re-authentication phase initiated
   by PaC

4.7.  Termination Phase

   A procedure for explicitly terminating a PANA session can be
   initiated either from the PaC (i.e., disconnect indication) or from
   the PAA (i.e., session revocation).  The PANA-Termination-Request and
   PANA-Termination-Answer message exchanges are used for disconnect
   indication and session revocation procedures.

   The reason for termination is indicated in the Termination-Cause AVP.
   When there is an established PANA SA between the PaC and the PAA, all
   messages exchanged during the termination phase MUST be protected
   with an AUTH AVP.  When the sender of the PANA-Termination-Request
   message receives a valid acknowledgment, all states maintained for
   the PANA session MUST be deleted immediately.

   PaC      PAA     Message(sequence number)[AVPs]
   ------------------------------------------------------
      ----->        PANA-Termination-Request(q)[Session-Id, AUTH]
      <-----        PANA-Termination-Answer(q)[Session-Id, AUTH]

   Figure 8: 7: Example sequence for the termination phase triggered by PaC

4.8.  Separate NAP and ISP Authentication

5.  Processing Rules

5.1.  Fragmentation

   PANA allows running at most two does not provide fragmentation of PANA messages.  Instead, it
   relies on fragmentation provided by EAP sessions in sequence in the
   authentication methods and authorization phase IP layer when
   needed.

5.2.  Sequence Number and Retransmission

   PANA uses sequence numbers to support separate NAP provide ordered and
   ISP authentication as described in this section.  A typical network
   access authentication includes execution reliable delivery
   of one EAP method with the
   ISP.  This separation allows the messages.

   The PaC and PAA maintain two sequence numbers: the next one to perform an additional
   authentication method be
   used for receiving differentiated services from a request it initiates and the
   NAP.

   Currently, running multiple EAP sessions in sequence next one it expects to see in
   a request from the
   authentication other end.  These sequence numbers are 32-bit
   unsigned numbers.  They are monotonically incremented by 1 as new
   requests are generated and authorization phase is designed only for separate
   NAP received, and ISP authentication.  It is not for running arbitrary number
   of EAP sessions in sequence, or giving the PaC another chance wrapped to try
   another EAP authentication method within an integrated NAP and ISP
   authentication when an EAP authentication method fails.

   Within separate NAP and ISP authentication, the NAP authentication
   and zero on the ISP authentication are considered completely independent.
   Presence or success of one should not effect next
   message after 2^32-1.  Answers always contain the other.  Making a
   network access authorization decision based on same sequence
   number as the success or failure
   of each authentication is a network policy issue.

4.8.1.  Negotiating Separate NAP and ISP Authentication

   When corresponding request.  Retransmissions reuse the PaC and PAA negotiates
   sequence number contained in the discovery and handshake phase
   to perform separate NAP and ISP authentication, original packet.

   The initial sequence numbers (ISN) are randomly picked by the PaC and the
   PAA
   operate as they send their very first request messages.  PANA-Client-
   Initiation message carries sequence number 0.

   When a request message is received, it is considered valid in terms
   of sequence numbers if and only if its sequence number matches the following way in addition
   expected value.  This check does not apply to the behavior defined PANA-Client-
   Initiation, PANA-Start-Request messages.

   When an answer message is received, it is considered valid in
   Section 4.3

   In the discovery and handshake phase, the PAA MAY advertise
   availability terms
   of separate NAP sequence numbers if and ISP authentication ([I-D.ietf-pana-
   framework]) by setting the S-flag on only if its sequence number matches that
   of the currently outstanding request.  A peer can only have one
   outstanding request at a time.

   PANA header of messages are retransmitted based on a timer until a response is
   received (in which case the PANA-
   Start-Request message.

   If retransmission timer is stopped) or the S-flag
   number of retransmission reaches the received PANA-Start-Request message is set, the
   PaC can indicate its desire to perform separate NAP and ISP
   authentication by setting maximum value (in which case the S-flag
   PANA session MUST be deleted immediately).

   The retransmission timers SHOULD be calculated as described in
   Section 9 unless a given deployment chooses to use its own
   retransmission timers optimized for the PANA-Start-Answer
   message.  If the S-flag of the received PANA-Start-Request message is
   not set, the underlying link-layer
   characteristics.

   The PaC and PAA MUST NOT set the S-flag in the PANA-Start-Answer
   message sent back respond to duplicate requests as long as the PAA.

   If the S-flag
   responding rate does not exceed a certain threshold value.  The last
   transmitted answer MAY be cached in the PANA-Start-Answer message case it is not set, only one
   authentication is performed (ISP-only) received by the
   peer and that generates a retransmission of the processing occurs as
   described in Section 4.3. last request.  When
   available, the S-flag is set in a PANA-Start-Request message, cached answer can be used instead of fully processing
   the initial retransmitted request and forming a new answer from scratch.

   PANA MUST NOT generate EAP Request message duplication.  EAP payload of a
   retransmitted PANA message MUST NOT be carried in the PANA-Start-Request
   message.  (If passed to the initial EAP Request message were contained in the
   PANA-Start-Request message during the S-flag negotiation, the PaC
   cannot tell whether the layer.

5.3.  PANA Security Association

   A PANA SA is created as an attribute of a PANA session when EAP Request message
   authentication succeeds with a creation of an MSK.  A PANA SA is for NAP not
   created when the PANA authentication fails or ISP authentication.)

4.8.2.  Execution of Separate NAP and ISP Authentication no MSK is produced by
   any EAP authentication method.  When a new MSK is derived in the PaC and PAA have negotiated in PANA
   re-authentication phase, any key derived from the discovery and handshake
   phase old MSK MUST be
   updated to perform separate NAP and ISP authentication, the PaC and the
   PAA operate in a new one that is derived from the following way in addition new MSK.  In order to
   distinguish the behavior defined
   in Section 4.4

   o  The S-flag of PANA-Auth-Request and PANA-Auth-Answer messages new MSK from old ones, one Key-Id AVP MUST be set.

   o  An EAP Success/Failure message is carried
   in a PANA-FirstAuth-End-
      Request (PFER) message as well as a PANA-Bind-Request (PBR)
      message.  The PANA-FirstAuth-End-Request message MUST be used and PANA-Bind-Answer messages at the end of the first
   EAP authentication which resulted in deriving a new MSK.  The Key-Id
   AVP is of type Unsigned32 and MUST contain a value that uniquely
   identifies the MSK within the PANA session.  The PANA-Bind-Answer
   message sent in response to a PANA-Bind-Request message with a Key-Id
   AVP MUST be used for contain a Key-Id AVP with the second EAP authentication.  The PANA-
      FirstAuth-End-Request same MSK identifier carried in
   the request.  PANA-Bind-Request and PANA-Bind-Answer messages MUST be acknowledged with a PANA-
      FirstAuth-End-Answer (PFEA) message.

   o  If
   Key-Id AVP MUST also carry an AUTH AVP whose value is computed by
   using the first EAP authentication has failed, new PANA_AUTH_KEY derived from the PAA can choose new MSK.  Although the
   specification does not
      to perform mandate a particular method for calculation of
   the second EAP authentication Key-Id AVP value, a simple method is to use monotonically
   increasing numbers.

   The PANA session lifetime is bounded by clearing the S-flag of authorization lifetime
   granted by the PANA-FirstAuth-End-Request message.  In this case, authentication server (same as the S-flag MSK lifetime).  The
   lifetime of the PANA-FirstAuth-End-Answer message sent by PANA SA (hence the PaC MUST be
      cleared.  If PANA_AUTH_KEY) is the S-flag same as the
   lifetime of the PANA-FirstAuth-End-Request message PANA session.  The created PANA SA is set deleted when
   the first EAP authentication has failed, the PaC can
      choose not to perform the second EAP authentication by clearing
      the S-flag of the PANA-FirstAuth-End-Answer message.  If the first
      EAP authentication failed and the S-flag corresponding PANA session is not set in the PANA-
      FirstAuth-End-Answer message deleted.

   PANA SA attributes as well as a result of those operations, the PANA session MUST be immediately deleted.  Otherwise, attributes are listed
   below:

   PANA Session attributes:

      *  Session-Id

      *  Device-Id of PaC

      *  IP address and UDP port number of the second
      EAP authentication MUST be performed.

   o  The PaC.

      *  IP address of PAA determines

      *  List of device identifiers of EPs

      *  Sequence number of the execution order last transmitted request

      *  Sequence number of NAP authentication and
      ISP authentication.  In this case, the last received request

      *  Last transmitted message payload

      *  Retransmission interval

      *  Session lifetime

      *  Protection-Capability

      *  PANA SA attributes

   PANA SA attributes:

      *  Nonce generated by PaC (PaC_nonce)

      *  Nonce generated by PAA can indicate which
      authentication (NAP authentication or ISP authentication) (PAA_nonce)

      *  MSK

      *  MSK Identifier

      *  PANA_AUTH_KEY

      *  Pseudo-random function

      *  Integrity algorithm

   The PANA_AUTH_KEY is
      currently occurring by using N-flag in derived from the available MSK and it is used to
   integrity protect PANA message header.
      When NAP authentication messages.  The PANA_AUTH_KEY is being performed, computed in
   the N-flag MUST be
      set.  When ISP authentication is being performed, following way:

   PANA_AUTH_KEY = prf+(MSK, PaC_nonce | PAA_nonce | Session-ID)

   where the N-flag MUST
      NOT be set. prf+ function is defined in IKEv2 [RFC4306].  The N-flag MUST NOT pseudo-
   random function to be set when S-flag is not set.

   When used for the PaC and PAA have negotiated prf+ function is specified in the discovery and handshake
   phase to perform separate NAP and ISP authentication, and the lower-
   layer is insecure, the two EAP authentication methods used
   Algorithm AVP in the
   separate authentication MUST be capable a PANA-Bind-Request message.  The length of deriving keys (AAA-Key).

4.8.3.  AAA-Key Calculation

   When
   PANA_AUTH_KEY depends on the PaC and PAA have negotiated integrity algorithm in use.  See
   Section 5.4 for the discovery and handshake
   phase to perform separate NAP and ISP authentication, if detailed usage of the lower-
   layer is insecure, PANA_AUTH_KEY.

5.4.  Message Authentication

   A PANA message can contain an AUTH AVP for cryptographically
   protecting the two EAP authentication methods used message.

   When an AUTH AVP is included in a PANA message, the
   separate authentication MUST be capable value field of deriving keys.  In this
   case, if
   the first EAP authentication AUTH AVP is successful, calculated by using the PANA-
   FirstAuth-End-Request and PANA-FirstAuth-End-Answer messages as well
   as PANA-Auth-Request and PANA-Auth-Answer messages PANA_AUTH_KEY in the second EAP
   authentication MUST be protected with
   following way:

      AUTH AVP value = PANA_AUTH_HASH(PANA_AUTH_KEY, PANA_PDU)

   where PANA_PDU is the key derived from PANA message including the AAA-
   Key for PANA header, with
   the AUTH AVP value field first EAP authentication.  The PANA-Bind-Request and
   PANA-Bind-Answer messages and all subsequent PANA messages exchanged initialized to 0.  PANA_AUTH_HASH
   represents the integrity algorithm specified in the access phase, re-authentication phase Algorithm AVP in
   a PANA-Bind-Request message.  The PaC and termination phase PAA MUST be protected either with the AAA-Key for the first EAP
   authentication if use the first EAP authentication succeeds same
   integrity algorithm to calculate an AUTH AVP they originate and
   receive.  The algorithm is determined by the
   second EAP authentication fails, or with PAA.  When the AAA-Key for PaC does
   not support the second
   EAP authentication if integrity algorithm specified in the first EAP authentication fails and the
   second EAP authentication succeeds, or with the compound AAA-Key
   derived from the two AAA-Keys, one for the first EAP authentication
   and the other from PANA-Bind-
   Request message, it MUST silently discard the second EAP authentication, if both message.

5.5.  Message Validity Check

   When a PANA message is received, the first
   and second EAP authentication succeed.  See Section 5.3 for how message is considered to
   derive be
   invalid at least when one of the AAA-Key.

5.  Processing Rules

5.1.  Fragmentation

   PANA does following conditions are not provide fragmentation of PANA messages.  Instead, it
   relies on fragmentation provided by EAP methods and IP layer when
   needed.

5.2.  Sequence Number and Retransmission

   PANA uses met:

   o  Each field in the message header contains a valid value including
      sequence numbers to provide ordered and reliable delivery
   of messages. number, message length, message type, version number,
      flags, etc.

   o  The PaC and PAA maintain two sequence numbers: the next message type is one to be
   used for a request it initiates and of the next one it expects to see expected types in
   a request from the other end.  These sequence numbers are 32-bit
   unsigned numbers.  They are monotonically incremented by 1 as new
   requests current
      state.  Specifically the following messages are generated unexpected and received,
      invalid:

      *  In the handshake phase:

         +  PANA-Termination-Request and wrapped to zero on PANA-Ping-Request.

         +  PANA-Bind-Request.

         +  PANA-Update-Request.

         +  PANA-Reauth-Request.

         +  PANA-Error-Request.

      *  In the next
   message authentication and authorization phase and the re-
         authentication phase:

         +  PANA-Client-Initiation.

         +  PANA-Update-Request.

         +  PANA-Start-Request after 2^32-1.  Answers always contain a PaC receives the same sequence
   number as first valid
            PANA-Auth-Request.

         +  PANA-Termination-Request before the corresponding request.  Retransmissions reuse PaC receives the
   sequence number contained in the original packet.

   The initial sequence numbers (ISN) are randomly picked by first
            successful PANA-Bind-Request.

      *  In the PaC and
   PAA access phase:

         +  PANA-Start-Request as they send their very first request messages.  PANA-PAA-
   Discover well as a non-duplicate PANA-Bind-
            Request.

         +  PANA-Client-Initiation.

      *  In the termination phase:

         +  PANA-Client-Initiation.

         +  All requests but PANA-Termination-Request.

   o  The message carries sequence number 0.

   When payload contains a request valid set of AVPs allowed for the
      message type and there is received, it is considered valid no missing AVP that needs to be included
      in terms
   of sequence numbers if the payload and only if its sequence number no AVP, which needs to be at a fixed position,
      is included in a position different from this fixed position.

   o  Each AVP is decoded correctly.

   o  When an AUTH AVP is included, the AVP value matches the
   expected value.  This check does not apply to hash value
      computed against the PANA-PAA-Discover,
   PANA-Start-Request messages. received message.

   o  When an answer message a Device-Id AVP is received, it included, the AVP is considered valid in terms
   of sequence numbers if the device
      identifier type contained in the AVP is supported (check performed
      by both the PaC and only if its sequence number matches that
   of the currently outstanding request.  A peer can only have PAA) and is the requested one
   outstanding request at (check
      performed by the PAA only).  Note that a time.

   PANA Device-Id AVP carries the
      device identifier of the PaC in messages are retransmitted based on a timer until a response is
   received (in which case from the retransmission timer is stopped) or PaC to the
   number PAA
      and the device identifier(s) of retransmission reaches the maximum value (in which case EP(s) in messages from the
   PANA session PAA
      to the PaC.

   Invalid messages MUST be deleted immediately).

   The retransmission timers SHOULD be calculated as described discarded in
   [RFC2988] order to provide congestion control. robustness
   against DoS attacks.  In addition, an error notification message MAY
   be returned to the sender.  See Section 9 5.11 for default
   timer and maximum retransmission count parameters.

   The PaC and PAA MUST respond to duplicate requests as long as the
   responding rate does not exceed a certain threshold value.  The last
   transmitted answer MAY be cached details.

5.6.  PaC-EP-Master-Key

   As described in case it is not received by the
   peer and that generates a retransmission of the last request.  When
   available, the cached answer can be used instead of fully processing
   the retransmitted request and forming a new answer from scratch.

   PANA MUST NOT generate EAP message duplication.  EAP payload Section 4.4, use of a
   retransmitted PANA message MUST NOT be passed to the EAP layer.

5.3.  PANA Security Association

   A PANA SA cryptographic filtering
   mechanism is created as an attribute of a PANA session when EAP
   authentication succeeds with a creation indicated by inclusion of a AAA-Key.  A PANA SA is
   not created when the PANA authentication fails or no AAA-Key is
   produced by any EAP authentication method.  In the case where two EAP
   sessions are performed Protection-Capability AVP in sequence
   the PANA-Bind-Request message in the PANA authentication and authorization phase, it is possible that two AAA-Keys are derived.
   If
   phase.  In this happens, the PANA SA MUST be generated from both AAA-Keys.
   When case, a new AAA-Key PaC-EP-Master-Key is derived in the PANA re-authentication phase,
   any key derived from the old AAA-Key MUST be updated to MSK for
   each EP and used by a new one
   that is derived from the new AAA-Key.  In order to distinguish the
   new AAA-Key from old ones, one Key-Id AVP MUST be carried in PANA-
   Bind-Request and PANA-Bind-Answer messages secure association protocol for bootstrapping
   link-layer or PANA-FirstAuth-End-
   Request and PANA-FirstAuth-End-Answer messages at the end of IPsec ciphering between the EAP
   authentication which resulted in deriving a new AAA-Key. PaC and EP.  The Key-Id
   AVP PaC-EP-
   Master-Key derivation algorithm is defined as follows.

   PaC-EP-Master-Key = The first 64 octets of type Unsigned32 and MUST contain a value that uniquely
   identifies the AAA-Key within the PANA session.
                       prf+(MSK, "PaC-EP master key" |
                            Session ID | Key-ID | EP-Device-Id)

   The PANA-Bind-Answer
   message (or prf+ function is defined in IKEv2 [RFC4306].  The pseudo-random
   function used for the PANA-FirstAuth-End-Answer message) sent prf+ function is specified in response
   to a PANA-Bind-Request message (or a PANA-FirstAuth-End-Request
   message) with a Key-Id AVP MUST contain a Key-Id AVP with the same
   AAA-Key identifier Algorithm AVP
   carried in the request.  PANA-Bind-Request, PANA-
   Bind-Answer, PANA-FirstAuth-End-Request and PANA-FirstAuth-End-Answer
   messages with a Key-Id AVP MUST also carry an AUTH AVP whose value is
   computed by using the new PANA_AUTH_KEY derived from the new AAA-Key
   (or the new pair of AAA-Keys when the PANA_AUTH_KEY PANA-Bind-Request message.

   EP-Device-Id is derived from
   two AAA-Keys).  Although the specification does not mandate a
   particular method for calculation Data field of the Key-Id Device-Id AVP value, a simple
   method is to use monotonically increasing numbers.

   The PANA session lifetime is bounded by the authorization lifetime
   granted by the authentication server (same as for the AAA-Key lifetime).
   corresponding EP.

5.7.  Device ID Choice

   The lifetime of the PANA SA (hence the PANA_AUTH_KEY) is the same as device identifier used in the lifetime context of the PANA session.  The created PANA SA is deleted
   when the corresponding PANA session is deleted.

   PANA SA attributes as well as PANA session attributes are listed
   below:

   PANA Session attributes:

      *  Session-Id

      *  Device-Id of PaC

      *  IP address and UDP port number of the PaC.

      * can be an IP address of PAA

      *  List of
   address, a MAC address, or an identifier that may not be carried in
   data packets but has local significance in identifying a connected
   device identifiers of EPs

      *  Sequence number of the (e.g., circuit id, PPP interface id).  The last transmitted request

      *  Sequence number type of the last received request

      *  Last transmitted message payload

      *  Retransmission interval

      *  Session lifetime

      *  Protection-Capability

      *  PANA SA attributes

   PANA SA attributes:

      *  Nonce generated by PaC (PaC_nonce)

      *  Nonce generated by PAA (PAA_nonce)

      *  AAA-Key

      *  AAA-Key Identifier

      *  PANA_AUTH_KEY

      *  Pseudo-random function

      *  Integrity algorithm

   The PANA_AUTH_KEY is derived from the
   identifiers (i.e., locally-significant identifiers) are commonly used
   in point-to-point links where MAC addresses are not available AAA-Key(s) and it is
   lower-layers are already physically or cryptographically secured.
   The locally-significant identifiers are used locally to integrity protect associate
   PANA messages.  If there is only one AAA-
   Key available, e.g., due to ISP-only authentication, or sessions with one
   failed and one successful separate NAP and ISP authentication (see
   Section 4.8), the PANA_AUTH_KEY computation is based on that single
   key.  Otherwise, two AAA-Keys available local interfaces and are not meant to PANA can be combined in
   following way ('|' indicates concatenation):

      AAA-Key = AAA-Key1 | AAA-Key2

   The PANA_AUTH_KEY
   exchanged with the peers.

   It is computed in assumed that the following way:

   PANA_AUTH_KEY = prf+(AAA-Key, PaC_nonce | PAA_nonce | Session-ID)

   where PAA knows the prf+ function is defined in IKEv2 [RFC4306].  The pseudo-
   random function to be used for the prf+ function is specified in link type and the
   Algorithm AVP in a PANA-FirstAuth-End-Request security
   mechanisms being provided or a PANA-Bind-Request
   message.  The length of PANA_AUTH_KEY depends required on the integrity
   algorithm in use.  See Section 5.4 for the detailed usage of access network based on
   configuration by the
   PANA_AUTH_KEY.

5.4.  Message Authentication

   A PANA message can contain an AUTH AVP network administrator.  For example, one network
   administrator might want to use IPsec for cryptographically
   protecting securing the message. network access
   while another one (for a different network) might rely on physical
   security.

   When an AUTH AVP IPsec-based security [I-D.ietf-pana-ipsec] is included in a PANA message, the value field choice of
   access control, the AUTH AVP is calculated by using the PANA_AUTH_KEY in the
   following way:

      AUTH AVP value = PANA_AUTH_HASH(PANA_AUTH_KEY, PANA_PDU)

   where PANA_PDU is the PANA message including the PANA header, with
   the AUTH AVP value field first initialized to 0.  PANA_AUTH_HASH
   represents the integrity algorithm specified in the Algorithm AVP in
   a PANA-Bind-Request message.  The PaC and PAA MUST use the same
   integrity algorithm to calculate an AUTH AVP they originate provide IP addresses as device
   identifiers of EPs, and
   receive.  The algorithm is determined by the PAA.  When expect the PaC does
   not support the integrity algorithm specified to provide its IP address in
   return.  Similarly, IP addresses are used as the PANA-Bind-
   Request message, it MUST silently discard the message.

5.5.  Message Validity Check

   When a PANA message is received, the message is considered to be
   invalid at least device identifiers
   when one of the following conditions EPs are not met:

   o  Each field in on the message header contains a valid value including
      sequence number, message length, message type, version number,
      flags, etc.

   o  The message type is one of same IP subnet as the expected types PaC.

   In other cases, MAC addresses are used as device identifiers when
   they are available.

   If non-IPsec access control is enabled, and a MAC address is not
   available, locally-significant identifiers (e.g., as a circuit id)
   MUST be used as device identifiers.  Note that these identifiers are
   not exchanged within PANA messages.  Instead, peers rely on lower-
   layers to provide them along with received PANA messages.

5.8.  PaC Updating its IP Address

   A PaC's IP address can change in certain situations.  For example,
   Appendix A describes a case in which a PaC replaces a pre-PANA
   address (PRPA - the current
      state.  Specifically IP address configured prior to PANA) with a post-
   PANA address (POPA - the following messages are unexpected and
      invalid:

      * new IP address configured after PANA, as
   required by some deployments).  In another situation a PaC may change
   its IP address used for PANA when it moves from one IP link to
   another within the discovery and handshake phase:

         +  PANA-Termination-Request and PANA-Ping-Request.

         +  PANA-Bind-Request.

         +  PANA-Update-Request.

         +  PANA-Reauth-Request.

         +  PANA-Error-Request.

      * same PAA's realm.  In order to maintain the authentication and authorization phase and PANA
   session, the re-
         authentication phase:

         +  PANA-PAA-Discover.

         +  PANA-Update-Request.

         +  PANA-Start-Request after a PAA needs to be notified about the change of PaC receives
   address.

   If the first valid
            PANA-Auth-Request.

         +  PANA-Termination-Request before device identifier of the PaC receives is the first
            successful PANA-Bind-Request.

      *  In IP address, it is also
   subject to the access phase:

         +  PANA-Start-Request as well as a non-duplicate PANA-Bind-
            Request.

         +  PANA-PAA-Discover.

      *  In the termination phase:

         +  PANA-PAA-Discover.

         +  All requests but PANA-Termination-Request.

   o same change.  The message payload contains a valid set of AVPs allowed for the
      message type and there is no missing AVP that needs to be included
      in the payload and no AVP, which PAA needs to be at a fixed position,
      is included in a position different from this fixed position.

   o  Each AVP is decoded correctly.

   o  When an AUTH AVP is included, the AVP value matches the hash value
      computed against the received message.

   o  When a Device-Id AVP is included, the AVP is valid if notified about the
   change of device identifier type contained in as well so that the AVP PAA can update the
   EPs.  If IPsec is supported (check performed
      by both used between the PaC and the PAA) and EPs, an IKE [RFC2409]
   IKEv2 [RFC4306] or MOBIKE [I-D.ietf-mobike-protocol] run is needed
   following such a change.

   After the requested one (check
      performed by PaC has changed its IP address, it MUST send a PANA-Update-
   Request message to the PAA only).  Note that PAA.  If the PaC has also changed its device
   identifier, the PANA-Update-Request message MUST include a Device-Id
   AVP carries containing the new device identifier of identifier.  The PAA MUST update the
   PANA session with the new PaC address carried in messages from the PaC to Source Address
   field of the PAA IP header and the new device identifier(s) of the EP(s) identifier carried in messages from the PAA
      to the PaC.

   Invalid messages MUST be discarded in order to provide robustness
   against DoS attacks.  In addition, an error notification
   Device-Id AVP, and return a PANA-Update-Answer message.  The PANA-
   Update-Answer message MAY
   be returned to the sender.  See Section 5.11 MUST contain one or more Device-Id AVPs for details.

5.6.  PaC-EP-Master-Key

   As described in Section 4.4, use of a cryptographic filtering
   mechanism is indicated by inclusion of a Protection-Capability AVP in
   the PANA-Bind-Request message in the authentication and authorization
   phase.  In this case, a PaC-EP-Master-Key is derived from
   EPs if the AAA-Key
   for each EP and used by a secure association protocol for
   bootstrapping link-layer or IPsec ciphering between set of EPs serving the PaC and EP.
   The PaC-EP-Master-Key derivation algorithm has also changed.  If there is defined as follows.

   PaC-EP-Master-Key = The first 64 octets of
                       prf+(AAA-Key, "PaC-EP master key" |
   an established PANA SA, both PANA-Update-Request and PANA-Update-
   Answer messages MUST be protected with an AUTH AVP.

5.9.  Session ID | Key-ID | EP-Device-Id)

   The prf+ function is defined in IKEv2 [RFC4306]. Lifetime

   The pseudo-random
   function used for authentication and authorization phase determines the prf+ function is specified in PANA
   session lifetime when the Algorithm network access authorization succeeds.  The
   Session-Lifetime AVP
   carried MAY be optionally included in a PANA-FirstAuth-End-Request or a PANA-Bind-Request
   message.

   EP-Device-Id is the Data field of the Device-Id AVP for PANA-Bind-
   Request message to inform the
   corresponding EP.

5.7.  Device ID Choice

   The device identifier used in PaC about the context valid lifetime of the
   PANA can session.  It MUST be an IP
   address, a MAC address, or an identifier that may ignored when included in other PANA
   messages.

   When the Session-Lifetime AVP is not be carried included in
   data packets but the PANA-Bind-
   Request message then the PaC has local significance in identifying no knowledge about a connected
   device (e.g., circuit id, PPP interface id).  The last type of
   identifiers are commonly used in point-to-point links where MAC
   addresses are not available PANA session
   limitation and lower-layers are already physically
   or cryptographically secured.

   It must therefore conclude that the session is assumed not
   limited.

   The lifetime is a non-negotiable parameter that can be used by the
   PaC to manage PANA-related state.  The PaC does not have to perform
   any actions when the lifetime expires, other than purging local
   state.  The PAA knows SHOULD initiate the link type PANA re-authentication phase
   before the current session lifetime expires.

   The PaC and the security
   mechanisms being provided or required on PAA MAY use information obtained outside PANA (e.g.,
   lower-layer indications) to expedite the access network (based on
   configuration detection of the network administrator).  For example, one a disconnected
   peer.  Availability and reliability of such indications MAY depend on
   a specific link-layer or network administrator might want to topology and are therefore only
   hints.  A PANA peer SHOULD use IPsec for securing the
   network access while another one (for PANA-Ping message exchange to
   verify that a different network) might rely
   on physical security.

   When IPsec-based security [I-D.ietf-pana-ipsec] peer is, in fact, no longer alive, unless information
   obtained outside PANA is being used to expedite the choice detection of
   access control, the PAA MUST provide IP address(es) as EP(s)' device
   ID, and expect the PaC a
   disconnected peer.

   The session lifetime parameter is not related to provide its IP address in return.
   Similarly, IP addresses are the transmission of
   PANA-Ping-Request messages.  These messages can be used when for
   asynchronously verifying the EP(s) liveness of the peer.  The decision to
   send a PANA-Ping-Request message is taken locally and does not on
   require coordination between the same IP
   subnet as peers.

5.10.  Network Selection

   The handshake phase allows the PaC is.

   In other cases, MAC addresses are used as device identifiers when
   they are available.

   If non-IPsec access control is enabled, to learn identity of the NAP and a MAC address is not
   available, locally-significant identifiers (e.g., as a circuit id)
   MUST be used as device id.  Note
   list of ISPs that these identifiers are not
   exchanged within PANA messages.  Instead, peers rely on lower-layers
   to provide them along with received PANA messages.

5.8.  PaC Updating its IP Address

   A PaC's IP address can change in certain situations.  For example, available through the PANA framework [I-D.ietf-pana-framework] describes a case in
   which a PaC replaces a pre-PANA address (PRPA) with a post-PANA
   address (POPA).  In another situation a NAP.  The PaC may change its IP address
   used for PANA when it moves from one IP link to another within can not
   only learn the
   same PAA's realm.  In order to maintain ISPs but also convey the PANA session, selected ISP explicitly
   during the handshake phase.  The PAA
   needs is assumed to be notified about pre-configured
   with the change information of PaC address.

   If ISPs that are served by the device identifier NAP.

   A PANA-Start-Request message sent from the PAA MAY contain zero or
   one NAP-Information AVP, and zero or more ISP-Information AVPs.  The
   PaC MAY indicate its choice of ISP by including an ISP-Information
   AVP in the PANA-Start-Answer message.  The PaC MAY convey its ISP
   even when there is no ISP-Information AVP contained in the IP address, PANA-
   Start-Request message.  The PaC can do that when it is also
   subject to the same change.  The PAA needs to be notified about pre-configured
   with ISP information.

   In the
   change absence of device identifier as well so that the PAA can update an ISP explicitly selected and conveyed by the
   EP(s).  If IPsec PaC,
   ISP selection is used between typically performed based on the PaC and client identifier
   (e.g., using the EPs, realm portion of an IKE or
   MOBIKE [I-D.ietf-mobike-protocol] NAI carried in EAP method).  A
   backend AAA protocol (e.g., RADIUS) will run is needed following such a
   change.

   After between the PaC has changed its IP address, it MUST send AAA client
   on the PAA and a PANA-Update-
   Request message to AAA server in the selected ISP domain.

   The PANA-based ISP selection mechanism dictates the next-hop AAA
   proxy on the PAA.  If the PaC has also changed NAP requires all AAA traffic to go through
   its device
   identifier, the PANA-Update-Request message MUST include local AAA proxy, it may have to rely on a Device-Id
   AVP containing mechanism to relay the new device identifier.  The
   selected ISP information from PAA MUST update (AAA client) to the
   PANA session with local AAA
   proxy.  The local AAA proxy can forward the new PaC address carried in AAA traffic to the Source Address
   field of
   selected ISP domain upon processing.  Further details, including how
   the IP header and AAA client relays AAA routing information to the new device identifier carried in AAA proxy, are
   outside the
   Device-Id AVP, and return a PANA-Update-Answer message.  The PANA-
   Update-Answer message MUST contain one or more Device-Id AVPs for scope of PANA.

   An alternative ISP selection mechanism is outlined in [RFC4284] which
   suggests advertising ISP information in-band with the
   EPs if ongoing EAP
   method execution.  Deployments using the set of EPs serving ISP selection mechanism
   defined in PANA need not use the PaC has also changed.  If there is
   an established PANA SA, both PANA-Update-Request and PANA-Update-
   Answer messages MUST be protected with an AUTH AVP.

5.9.  Session Lifetime

   The authentication and authorization phase determines the PANA
   session lifetime when the network access authorization succeeds.  The
   Session-Lifetime AVP alternative ISP selection mechanism.

5.11.  Error Handling

   A PANA-Error-Request message MAY be optionally included in sent by either the PANA-Bind-
   Request PaC or the PAA
   when a badly formed PANA message is received or in case of other
   errors.  The receiver of this request MUST respond with a PANA-Error-
   Answer message.

   An adversary might craft erroneous PANA messages to inform launch a Denial
   of Service attack.  Unless the PaC about or the valid lifetime PAA performs a rate-
   limitation of the
   PANA session.  It MUST generated PANA-Error-Request messages it may be ignored when included in other PANA
   overburdened by responding to bogus messages.

   When the Session-Lifetime AVP  Note that a PANA-
   Error-Answer message that is not included sent in the PANA-Bind-
   Request response to a PANA-Error-Request
   message then does not require either the PaC has no knowledge about or the PAA to create a PANA session
   limitation and must therefore conclude state.

   If an error message is sent unprotected (i.e., without using an AUTH
   AVP) then the error message MUST be processed such that the session is receiver
   does not
   limited.

   The lifetime change its state.

6.  Header Format

   This section defines message formats for PANA protocol.

6.1.  IP and UDP Headers

   Any PANA message is a non-negotiable parameter that can be used by unicast between the PaC to manage PANA-related state. and the PAA.  The PaC does not have source
   and destination addresses SHOULD be set to perform
   any actions when the lifetime expires, other than purging local
   state.  The PAA SHOULD initiate addresses on the PANA re-authentication phase
   before
   interfaces from which the current session lifetime expires.

   The PaC message will be sent and received,
   respectively.

   When the PAA MAY use information obtained outside PANA (e.g.,
   lower-layer indications) message is sent in response to expedite the detection of a disconnected
   peer.  Availability request, the UDP
   source and reliability destination ports of such indications MAY depend on
   a specific link layer or network topology and are therefore only
   hints.  A PANA peer SHOULD use the PANA-Ping response message exchange to
   verify the liveness of a peer before taking an action.

   The session lifetime parameter is not related to the transmission of
   PANA-Ping-Request messages.  These messages can MUST be used for
   asynchronously verifying copied
   from the liveness destination and source ports of the peer. request message,
   respectively.

   The decision source port of an unsolicited PANA message MUST be set to
   send a PANA-Ping-Request message is taken locally and does not
   require coordination between the peers.

   When separate ISP and NAP authentication is performed, it is possible
   that different authorization lifetime values are associated with the
   two EAP authentication sessions.  In this case, the smaller
   authorization lifetime value
   chosen by the sender.  The destination port MUST be used for calculating set to the peer's
   port number if it has already been discovered via earlier PANA
   Session-Lifetime value.  As a result, both NAP and ISP authentication
   will be performed in
   exchanges, set to the re-authentication phase.

5.10.  Network Selection

   The assigned PANA discovery and handshake phase allows the PaC to learn
   identity port (To Be Assigned by IANA)
   otherwise.

6.2.  PANA Header

   A summary of the NAP and a list of ISPs that PANA header format is shown below.  The fields are available through
   transmitted in network byte order.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    |   Reserved    |        Message Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Flags              |         Message Type          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Sequence Number                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  AVPs ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-

   Version

      This Version field MUST be set to 1 to indicate PANA Version 1.

   Reserved
      This 8-bit field is reserved for future use, and MUST be set to
      zero, and ignored by the
   NAP. receiver.

   Message Length

      The PaC can not only learn Message Length field is two octets and indicates the ISPs but also convey length of
      the
   selected ISP explicitly during PANA message including the handshake phase. header fields.

   Flags

      The PAA Flags field is
   assumed to be pre-configured with the information of ISPs that two octets.  The following bits are
   served by assigned:

    0                   1
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R L r r r r r r r r r r r r r r|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      R(equest)

         If set, the NAP.

   A message is a request.  If cleared, the message is
         an answer.

      L(stateLess handshake)

         When the L-flag is set in a PANA-Start-Request message sent from it
         indicates that the PAA MAY contain zero or
   one NAP-Information AVP, is performing stateless handshake.
         Cookie AVP MUST be included in both the PANA-Start-Request and zero or more ISP-Information AVPs.  The
   PaC MAY indicate its choice of ISP by including an ISP-Information
   AVP in
         the PANA-Start-Answer message.  The PaC MAY convey its ISP
   even messages when there performing stateless
         handshake.

      r(eserved)

         These flag bits are reserved for future use, and MUST be set to
         zero, and ignored by the receiver.

   Message Type

      The Message Type field is no ISP-Information AVP contained two octets, and is used in order to
      communicate the message type with the PANA-
   Start-Request message.  The PaC can do that when it 16-bit address
      space is pre-configured
   with ISP information.

   In the absence of an ISP explicitly selected and conveyed managed by IANA [ianaweb].  PANA uses its own address
      space for this field.

   Sequence Number
      The Sequence Number field contains a 32 bit value.

   AVPs

      AVPs are a method of encapsulating information relevant to the PaC,
   ISP selection is typically performed based
      PANA message.  See section Section 6.3 for more information on the client identifier
   (e.g., using the realm portion
      AVPs.

6.3.  AVP Header

   Each AVP of an NAI carried in EAP method). type OctetString MUST be padded to align on a 32-bit
   boundary, while other AVP types align naturally.  A
   backend AAA protocol (e.g., RADIUS) will run between number of zero-
   valued bytes are added to the AAA client
   on end of the PAA and AVP Data field till a AAA server word
   boundary is reached.  The length of the padding is not reflected in
   the selected ISP domain. AVP Length field [RFC3588].

   The PANA-based ISP selection mechanism dictates the next-hop AAA
   proxy on fields in the PAA.  If AVP header are sent in network byte order.  The
   format of the NAP requires all AAA traffic to go through
   its local AAA proxy, it may have to rely on a mechanism to relay the
   selected ISP information from PAA (AAA client) to the local AAA
   proxy. header is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           AVP Code            |           AVP Flags           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          AVP Length           |            Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Vendor-Id (opt)                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Data ...
   +-+-+-+-+-+-+-+-+

   AVP Code

      The local AAA proxy can forward the AAA traffic to AVP Code, combined with the
   selected ISP domain upon processing.  Further details, including how Vendor-Id field, identifies the AAA client relays AAA routing information to
      attribute uniquely.  AVP numbers are allocated by IANA [ianaweb].
      PANA uses its own address space for this field although some of
      the AAA proxy, AVP formats are
   outside borrowed from Diameter protocol [RFC3588].

   AVP Flags

      The AVP Flags field is two octets.  The following bits are
      assigned:

    0                   1
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |V M r r r r r r r r r r r r r r|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      M(andatory)

         The 'M' Bit, known as the scope Mandatory bit, indicates whether
         support of PANA.

   An alternative ISP discovery mechanism the AVP is outlined in [RFC4284] which
   suggests advertising ISP information in-band required.

         If an AVP with the ongoing EAP
   method execution.  Deployments using 'M' bit set is received by the PANA's built-in ISP
   discovery mechanism need not use the other mechanism.

5.11.  Error Handling

   A PANA-Error-Request message MAY be sent by PaC or PAA
         and either the PaC AVP or its value is unrecognized, the PAA
   when a badly formed PANA message is received or in case of other
   errors.  The
         MUST be rejected and the receiver of this request MUST respond with send a PANA-Error-
   Answer
         Request message.

   An adversary might craft erroneous PANA messages to launch a Denial
   of Service attack.  Unless  If the PaC or AVP was unrecognized the PAA performs a rate-
   limitation of PANA-Error-
         Request message result code MUST be PANA_AVP_UNSUPPORTED.  If
         the AVP value was unrecognized the generated PANA-Error-Request messages it may message
         result code MUST be
   overburdened by responding to bogus messages.  Note PANA_INVALID_AVP_DATA.  In either case the
         PANA-Error-Request message MUST carry a Failed-AVP AVP
         containing the offending mandatory AVP.

         AVPs with the 'M' bit cleared are informational only and a
         receiver that receives a PANA-
   Error-Answer message with such an AVP that is sent in response to a PANA-Error-Request
   message does not require either the PaC
         recognized, or the PAA to create state.

   If an error message whose value is sent unprotected (i.e., without using an AUTH
   AVP) and not recognized, MAY simply ignore
         the lower-layer is insecure then AVP.

      V(endor)

         The 'V' bit, known as the error message MUST be
   processed such that Vendor-Specific bit, indicates
         whether the receiver does not change its state.

6.  Header Format

   This section defines message formats for PANA protocol.

6.1.  IP and UDP Headers

   When a PANA-PAA-Discover message optional Vendor-Id field is multicast, IP destination address
   of present in the message is AVP
         header.  When set the AVP Code belongs to a well-known administratively scoped
   multicast the specific vendor
         code address (To Be Assigned by IANA).  A PANA-PAA-Discover
   message MAY be unicast in some cases as specified in Section 4.3.
   Any other PANA message is unicast between the PaC and the PAA.  The
   source space.

      r(eserved)

         These flag bits are reserved for future use, and destination addresses SHOULD MUST be set to
         zero, and ignored by the addresses on
   the interfaces from which the message receiver.

      Unless otherwise noted, AVPs defined in this document will have
      the following default AVP Flags field settings: The 'M' bit MUST
      be sent set.  The 'V' bit MUST NOT be set.

   AVP Length

      The AVP Length field is two octets, and received,
   respectively.

   When indicates the PANA message is sent number of
      octets in response to a request, this AVP including the UDP
   source AVP Code, AVP Length, AVP Flags,
      and destination ports of the response message MUST be copied
   from the destination AVP data.

   Reserved

      This two-octet field is reserved for future use, and source ports of the request message,
   respectively.

   The source port of an unsolicited PANA message MUST be set
      to a value
   chosen zero, and ignored by the sender. receiver.

   Vendor-Id

      The destination port MUST be set to the peer's
   port number Vendor-Id field is present if it has already been discovered via earlier PANA
   exchanges, set to the assigned PANA port (To Be Assigned by IANA)
   otherwise.

6.2.  PANA Header

   A summary of the PANA header format 'V' bit is shown below. set in the AVP
      Flags field.  The fields are
   transmitted optional four-octet Vendor-Id field contains the
      IANA assigned "SMI Network Management Private Enterprise Codes"
      [ianaweb] value, encoded in network byte order.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    |   Reserved    |        Message Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Flags              |         Message Type          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Sequence Number                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  AVPs ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-
   Version

      This Version field MUST be set to 1  Any vendor
      wishing to indicate implement a vendor-specific PANA Version 1.

   Reserved

      This 8-bit field is reserved for future use, and AVP MUST be set to
      zero, and ignored by the receiver.

   Message Length use their own
      Vendor-Id along with their privately managed AVP address space,
      guaranteeing that they will not collide with any other vendor's
      vendor-specific AVP(s), nor with future IETF applications.

   Data

      The Message Length Data field is two zero or more octets and indicates contains information
      specific to the Attribute.  The format and length of the PANA message including the header fields.

   Flags

      The Flags Data
      field is two octets.  The following bits are assigned:

    0                   1
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R S N L r r r r r r r r r r r r|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      R(equest)

         If set, determined by the AVP Code and AVP Length fields.

7.  PANA Messages

   Each Request/Answer message pair is assigned a request.  If cleared, Sequence Number, and
   the message sub-type (i.e., request or answer) is
         an answer.

      S(eparate)

         When identified via the S-flag is set 'R' bit
   in the Message Flags field of the PANA header.

   Every PANA message MUST contain a PANA-Start-Request message it
         indicates that PAA ID in its header's Message
   Type field, which is willing used to offer separate NAP and ISP
         authentication.  When determine the S-flag action that is set in to be taken
   for a particular message.  Figure 8 lists all PANA messages defined
   in this document:

   Message-Name              Abbrev. ID PaC<->PAA  Ref.
   ----------------------------------------------------------
   PANA-Client-Initiation     PCI    1  -------->  7.1
   PANA-Start-Request         PSR    2  <--------  7.2
   PANA-Start-Answer          PSA    2  -------->  7.3
   PANA-Auth-Request          PAR    3  <------->  7.4
   PANA-Auth-Answer           PAN    3  <------->  7.5
   PANA-Reauth-Request        PRAR   4  -------->  7.6
   PANA-Reauth-Answer         PRAA   4  <--------  7.7
   PANA-Bind-Request          PBR    5  <--------  7.8
   PANA-Bind-Answer           PBA    5  -------->  7.9
   PANA-Ping-Request          PPR    6  <------->  7.10
   PANA-Ping-Answer           PPA    6  <------->  7.11
   PANA-Termination-Request   PTR    7  <------->  7.12
   PANA-Termination-Answer    PTA    7  <------->  7.13
   PANA-Error-Request         PER    8  <------->  7.14
   PANA-Error-Answer          PEA    8  <------->  7.15
   PANA-Update-Request        PUR    9  <------->  7.16
   PANA-Update-Answer         PUA    9  <------->  7.17
   -----------------------------------------------------------

   Figure 8: Table of PANA Messages

   Every PANA message it indicates that the PaC accepts on performing
         separate NAP and ISP authentication.  The PaC may also respond
         with the S-flag not set defined MUST include a corresponding ABNF
   [RFC2234] specification, which implies the PaC has chosen is used to
         authenticate with the ISP only.  When define the S-flag is set in a
         PANA-Auth-Request/Answer, PANA-FirstAuth-End-Request/Answer and
         PANA-Bind-Request/Answer messages it indicates AVPs that separate
         NAP and ISP authentication is being performed in the
         authentication and authorization phase.  For other cases,
         S-flag MUST NOT be set.

      N(AP authentication)
         When the N-flag is set in a PANA-Auth-Request, a PANA-
         FirstAuth-End-Request
   or a PANA-Bind-Request message, it
         indicates that the current EAP authentication is for NAP
         authentication.  When the N-flag MAY be present.  The following format is unset used in a PANA-Auth-
         Request, a PANA-FirstAuth-End-Request or a PANA-Bind-Request
         message, it indicates that the current EAP authentication is
         for ISP authentication.  The PaC MUST copy the value of the
         flag in its answer from the last received request of the PAA. definition:

   message-def      = Message-Name "::=" PANA-message

   message-name     = PANA-name

   PANA-name        = ALPHA *(ALPHA / DIGIT / "-")

   PANA-message     = header  [ *fixed] [ *required] [ *optional]
                      [ *fixed]

   header           = "< PANA-Header: " Message-Type
                      [r-bit] [s-bit] [n-bit] ">"

   Message-Type     = 1*DIGIT
                      ; The value of Message Type assigned to the flag on an answer MUST be copied from message

   r-bit            = ", REQ"
                      ; If present, the
         request.  The N-flag MUST NOT be set when S-flag 'R' bit in the Message
                      ; Flags is not set.

      L(stateLess discovery)

         When set, indicating that the L-flag message
                      ; is set in a PANA-Start-Request message it
         indicates that request, as opposed to an answer.

   l-bit            = ", SLS"
                      ; If present, the 'L' bit in the Message
                      ; Flags is set, indicating PAA is performing
                      ; stateless discovery.
         Cookie handshake.

   fixed            = [qual] "<" avp-spec ">"
                      ; Defines the fixed position of an AVP.

   required         = [qual] "{" avp-spec "}"
                      ; The AVP MUST be included present and can appear
                      ; anywhere in both the PANA-Start-Request and message.

   optional         = [qual] "[" avp-name "]"
                      ; The avp-name in the PANA-Start-Answer messages when performing stateless
         discovery.

      r(eserved)

         These flag bits are reserved for future use, and MUST be set 'optional' rule cannot
                      ; evaluate to
         zero, and ignored by the receiver.

   Message Type

      The Message Type field is two octets, and any AVP Name which is used included
                      ; in a fixed or required rule.  The AVP can
                      ; appear anywhere in order to
      communicate the message type with the message.

   qual             = [min] "*" [max]
                      ; See ABNF conventions, RFC 2234 Section 6.6.
                      ; The 16-bit address
      space is managed by IANA [ianaweb].  PANA uses its own address
      space for this field.

   Sequence Number

      The Sequence Number field contains a 32 bit value.

   AVPs

      AVPs are a method absence of encapsulating information relevant to the
      PANA message.  See section Section 6.3 for more information any qualifiers depends on
      AVPs.

6.3.  AVP Header

   Each whether
                      ; it precedes a fixed, required, or optional
                      ; rule.  If a fixed or required rule has no
                      ; qualifier, then exactly one such AVP of type OctetString MUST
                      ; be padded to align on a 32-bit
   boundary, while other present.  If an optional rule has no
                      ; qualifier, then 0 or 1 such AVP types align naturally.  A number of zero-
   valued bytes are added may be
                      ; present.
                      ;
                      ; NOTE:  "[" and "]" have a different meaning
                      ; than in ABNF (see the optional rule, above).
                      ; These braces cannot be used to express
                      ; optional fixed rules (such as an optional
                      ; AUTH at the end end).  To do this, the convention
                      ; is '0*1fixed'.

   min              = 1*DIGIT
                      ; The minimum number of times the AVP Data field till a word
   boundary element may
                      ; be present.  The default value is reached. zero.

   max              = 1*DIGIT
                      ; The length maximum number of times the padding element may
                      ; be present.  The default value is not reflected in infinity.  A
                      ; value of zero implies the AVP Length field [RFC3588]. MUST NOT be
                      ; present.

   avp-spec         = PANA-name
                      ; The fields in the avp-spec has to be an AVP header are sent Name, defined
                      ; in network byte order.  The
   format of the header is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           AVP Code            |           AVP Flags           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          AVP Length           |            Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Vendor-Id (opt)                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Data ...
   +-+-+-+-+-+-+-+-+

   AVP Code base or extended PANA protocol
                      ; specifications.

   avp-name         = avp-spec / "AVP"
                      ; The string "AVP" stands for *any* arbitrary
                      ; AVP Code, combined Name, which does not conflict with the Vendor-Id field, identifies the
      attribute uniquely.  AVP numbers are allocated by IANA [ianaweb].
      PANA uses its own address space for this field although some of
                      ; required or fixed position AVPs defined in
                      ; the message definition.

   Example-Request ::= < "PANA-Header: 9999999, REQ >
                       < Session-Id >
                       { Result-Code }
                    *  [ AVP formats are borrowed from Diameter protocol [RFC3588].

   AVP Flags ]
                   0*1 < AUTH >

7.1.  PANA-Client-Initiation (PCI)

   The AVP Flags field PANA-Client-Initiation (PCI) message is two octets. used for PaC-initiated
   handshake.  The following bits are
      assigned:

    0                   1
    0 1 2 3 4 5 6 7 8 9 0 sequence number in this message is always set to zero
   (0).

   PANA-Client-Initiation ::= < PANA-Header: 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |V M r r r r r r r r r r r r r r|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      M(andatory)

         The 'M' Bit, known as the Mandatory bit, indicates whether
         support of the >
                       [ Notification ]
                    *  [ AVP ]

7.2.  PANA-Start-Request (PSR)

   The PANA-Start-Request (PSR) message is required.

         If an AVP with sent by the 'M' bit set is received by PAA to the PaC or to
   start PANA authentication.  The PAA
         and either sets the sequence number to an
   initial random value.

   PANA-Start-Request ::= < PANA-Header: 2, REQ [,SLS] >
                       [ Nonce ]
                       [ Cookie ]
                       [ EAP-Payload ]
                       [ NAP-Information ]
                    *  [ ISP-Information ]
                       [ Protection-Capability]
                       [ Algorithm ]
                       [ PPAC ]
                       [ Notification ]
                    *  [ AVP or its value ]

7.3.  PANA-Start-Answer (PSA)

   The PANA-Start-Answer (PSA) message is unrecognized, sent by the message
         MUST be rejected and PaC to the receiver MUST send PAA in
   response to a PANA-Error-
         Request PANA-Start-Request message.  If the AVP was unrecognized the PANA-Error-
         Request  This message result code MUST be PANA_AVP_UNSUPPORTED.  If completes the
   handshake to start PANA authentication.

   PANA-Start-Answer ::= < PANA-Header: 2 >
                       [ Nonce ]
                       [ Cookie ]
                       [ EAP-Payload ]
                       [ ISP-Information ]
                       [ Notification ]
                    *  [ AVP value was unrecognized the PANA-Error-Request ]

7.4.  PANA-Auth-Request (PAR)

   The PANA-Auth-Request (PAR) message
         result code MUST be PANA_INVALID_AVP_DATA.  In is either case the
         PANA-Error-Request message MUST carry a Failed-AVP AVP
         containing sent by the offending mandatory AVP.

         AVPs with PAA or the 'M' bit cleared are informational only and a
         receiver that receives a message with such
   PaC.  Its main task is to carry an EAP-Payload AVP.

   PANA-Auth-Request ::= < PANA-Header: 3, REQ >
                       < Session-Id >
                       < EAP-Payload >
                       [ Nonce ]
                       [ Notification ]
                    *  [ AVP that ]
                   0*1 < AUTH >

7.5.  PANA-Auth-Answer (PAN)

   The PANA-Auth-Answer (PAN) message is not
         recognized, sent by either the PaC or whose value is not recognized, MAY simply ignore the
   PAA in response to a PANA-Auth-Request message.  It MAY carry an EAP-
   Payload AVP.

      V(endor)

   PANA-Auth-Answer ::= < PANA-Header: 3 >
                       < Session-Id >
                       [ Nonce ]
                       [ EAP-Payload ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.6.  PANA-Reauth-Request (PRAR)

   The 'V' bit, known as the Vendor-Specific bit, indicates
         whether the optional Vendor-Id field PANA-Reauth-Request (PRAR) message is present in the AVP
         header.  When set sent by the AVP Code belongs PaC to the specific vendor
         code address space.

      r(eserved)

         These flag bits are reserved for future use, and MUST be set PAA
   to
         zero, and ignored by the receiver.

      Unless otherwise noted, AVPs defined in this document will have
      the following default AVP Flags field settings: The 'M' bit MUST
      be set.  The 'V' bit MUST NOT be set. re-initiate EAP authentication.

   PANA-Reauth-Request ::= < PANA-Header: 4, REQ >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP Length ]
                   0*1 < AUTH >

7.7.  PANA-Reauth-Answer (PRAA)

   The AVP Length field PANA-Reauth-Answer (PRAA) message is two octets, and indicates the number of
      octets in this AVP including the AVP Code, AVP Length, AVP Flags,
      and sent by the AVP data.

   Reserved

      This two-octet field is reserved for future use, and MUST be set PAA to zero, and ignored by the receiver.

   Vendor-Id PaC
   in response to a PANA-Reauth-Request message.

   PANA-Reauth-Answer ::= < PANA-Header: 4 >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.8.  PANA-Bind-Request (PBR)

   The Vendor-Id field PANA-Bind-Request (PBR) message is present if sent by the 'V' bit is set in PAA to the AVP
      Flags field.  The optional four-octet Vendor-Id field contains PaC to
   deliver the
      IANA assigned "SMI Network Management Private Enterprise Codes"
      [ianaweb] value, encoded in network byte order.  Any vendor
      wishing to implement a vendor-specific result of PANA authentication.

   PANA-Bind-Request ::= < PANA-Header: 5, REQ >
                       < Session-Id >
                       { Result-Code }
                       [ PPAC ]
                       [ EAP-Payload ]
                       [ Session-Lifetime ]
                       [ Protection-Capability ]
                       [ Key-Id ]
                       [ Algorithm ]
                    *  [ Device-Id ]
                       [ Notification ]
                    *  [ AVP MUST use their own
      Vendor-Id along with their privately managed AVP address space,
      guaranteeing that they will not collide with any other vendor's
      vendor-specific AVP(s), nor with future IETF applications.

   Data
      The Data field is zero or more octets and contains information
      specific to the Attribute. ]
                   0*1 < AUTH >

7.9.  PANA-Bind-Answer (PBA)

   The format and length of the Data
      field PANA-Bind-Answer (PBA) message is determined sent by the PaC to the PAA in
   response to a PANA-Bind-Request message.

   PANA-Bind-Answer ::= < PANA-Header: 5 >
                       < Session-Id >
                       [ PPAC ]
                       [ Device-Id ]
                       [ Key-Id ]
                       [ Notification ]
                    *  [ AVP Code and AVP Length fields.

7.  PANA Messages

   Each Request/Answer ]
                   0*1 < AUTH >

7.10.  PANA-Ping-Request (PPR)

   The PANA-Ping-Request (PPR) message pair is assigned a Sequence Number, and either sent by the sub-type (i.e., request PaC or answer) is identified via the 'R' bit
   in the Message Flags field of the PANA header.

   Every PANA message MUST contain a
   PAA for performing liveness test.

   PANA-Ping-Request ::= < PANA-Header: 6, REQ >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.11.  PANA-Ping-Answer (PPA)

   The PANA-Ping-Answer (PPA) message ID in its header's
   Message-Id field, which is used sent in response to determine the action that is to be
   taken for a particular message.  Figure 9 lists all PANA messages
   defined in this document:

   Message-Name              Abbrev. ID PaC<->PAA  Ref.
   ----------------------------------------------------------
   PANA-PAA-Discover          PDI    1  -------->  7.1
   PANA-Start-Request         PSR    2  <--------  7.2
   PANA-Start-Answer          PSA    2  -------->  7.3
   PANA-Auth-Request          PAR    3  <------->  7.4
   PANA-Auth-Answer           PAN    3  <------->  7.5
   PANA-Reauth-Request        PRAR   4  -------->  7.6
   PANA-Reauth-Answer         PRAA   4  <--------  7.7
   PANA-Bind-Request          PBR    5  <--------  7.8
   PANA-Bind-Answer           PBA    5  -------->  7.9
   PANA-Ping-Request          PPR    6  <------->  7.10 PANA-
   Ping-Request.

   PANA-Ping-Answer           PPA ::= < PANA-Header: 6  <------->  7.11 >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.12.  PANA-Termination-Request   PTR    7  <------->  7.12
   PANA-Termination-Answer    PTA    7  <------->  7.13
   PANA-Error-Request         PER    8  <------->  7.14
   PANA-Error-Answer          PEA    8  <------->  7.15
   PANA-FirstAuth-End-Request PFER   9  <--------  7.16
   PANA-FirstAuth-End-Answer  PFEA   9  -------->  7.17
   PANA-Update-Request        PUR    10 <------->  7.18
   PANA-Update-Answer         PUA    10 <------->  7.19
   -----------------------------------------------------------

   Figure 9: Table of PANA Messages

   Every PANA (PTR)

   The PANA-Termination-Request (PTR) message defined MUST include a corresponding ABNF
   [RFC2234] specification, which is used to define sent either by the AVPs that MUST PaC
   or MAY be present.  The following format is used in the definition:

   message-def      = Message-Name "::=" PANA-message

   message-name     = PANA-name

   PANA-name        = ALPHA *(ALPHA / DIGIT / "-")

   PANA-message     = header  [ *fixed] [ *required] PAA to terminate a PANA session.

   PANA-Termination-Request ::= < PANA-Header: 7, REQ >
                       < Session-Id >
                       < Termination-Cause >
                       [ *optional] Notification ]
                    *  [ *fixed]
   header           = "< PANA-Header: " Message-Id
                      [r-bit] [s-bit] [n-bit] ">"

   Message-Id       = 1*DIGIT
                      ; AVP ]
                   0*1 < AUTH >

7.13.  PANA-Termination-Answer (PTA)

   The PANA-Termination-Answer (PTA) message code assigned to is sent either by the message

   r-bit            = ", REQ"
                      ; If present, PaC
   or the 'R' bit PAA in the Message
                      ; Flags is set, indicating that the response to PANA-Termination-Request.

   PANA-Termination-Answer ::= < PANA-Header: 7 >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.14.  PANA-Error-Request (PER)

   The PANA-Error-Request (PER) message
                      ; is a request, as opposed sent either by the PaC or the
   PAA to report an answer.

   s-bit            = ", SEP"
                      ; If present, the 'S' bit in error with the Message
                      ; Flags last received PANA message.

   PANA-Error-Request ::= < PANA-Header: 8, REQ >
                        < Session-Id >
                        < Result-Code >
                     *  [ Failed-AVP ]
                        [ Notification ]
                     *  [ AVP ]
                    0*1 < AUTH >

7.15.  PANA-Error-Answer (PEA)

   The PANA-Error-Answer (PEA) message is set, indicating support for
                      ; separate NAP and ISP authentication.

   n-bit            = ", NAP"
                      ; If present, the 'N' bit sent in the Message
                      ; Flags is set, indicating that current
                      ; EAP authentication response to a PANA-
   Error-Request.

   PANA-Error-Answer ::= < PANA-Header: 8 >
                        < Session-Id >
                        [ Notification ]
                     *  [ AVP ]
                    0*1 < AUTH >

7.16.  PANA-Update-Request (PUR)

   The PANA-Update-Request (PUR) message is for NAP authentication.

   l-bit            = ", SLS"
                      ; If present, sent either by the 'L' bit in PaC or
   the Message
                      ; Flags is set, indicating PAA is performing
                      ; stateless discovery

   fixed            = [qual] "<" avp-spec ">"
                      ; Defines to deliver attribute updates and notifications.  In the fixed position scope
   of an AVP

   required         = [qual] "{" avp-spec "}"
                      ; The AVP MUST be present this specification only the IP address and can appear
                      ; anywhere in device identifer of the
   PaC can be updated via this message.

   optional         = [qual] "[" avp-name "]"
                      ;

   PANA-Update-Request ::= < PANA-Header: 9, REQ >
                       < Session-Id >
                       [ Device-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.17.  PANA-Update-Answer (PUA)

   The avp-name in PANA-Update-Answer (PUA) message is sent by the 'optional' rule cannot
                      ; evaluate PAA (PaC) to any AVP Name which is included
                      ; the
   PaC (PAA) in response to a fixed PANA-Update-Request from the PaC (PAA).

   PANA-Update-Answer ::= < PANA-Header: 9 >
                       < Session-Id >
                    *  [ Device-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

8.  AVPs in PANA

   PANA defines several AVPs that are specific to the protocol.  A
   number of others AVPs are reused.  These are specified in other
   documents such as [RFC3588].

   The following tables lists the AVPs used in this document, and
   specifies in which PANA messages they MAY, or required rule. MAY NOT be present.

   The table uses the following symbols:

   0     The AVP can
                      ; appear anywhere MUST NOT be present in the message.

   qual             = [min] "*" [max]
                      ; See ABNF conventions, RFC 2234 Section 6.6.
                      ; The absence of any qualifiers depends on whether
                      ; it precedes a fixed, required, or optional
                      ; rule.  If a fixed

   0+    Zero or required rule has no
                      ; qualifier, then exactly one such more instances of the AVP MUST
                      ; MAY be present.  If an optional rule has no
                      ; qualifier, then 0 present in the
         message.

   0-1   Zero or 1 such one instance of the AVP may MAY be
                      ; present.

                      ;
                      ; NOTE:  "[" and "]" have a different meaning
                      ; than present in ABNF (see the optional rule, above).
                      ; These braces cannot be used to express
                      ; optional fixed rules (such as an optional
                      ; AUTH at the end).  To do this, the convention
                      ; is '0*1fixed'.

   min              = 1*DIGIT
                      ; The minimum number of times the element may
                      ; be present.  The default value message.
         It is zero.

   max              = 1*DIGIT
                      ; The maximum number considered an error if there are more than one instance
         of times the element may
                      ; be present.  The default value is infinity.  A
                      ; value AVP.

   1     One instance of zero implies the AVP MUST NOT be
                      ; present.

   avp-spec         = PANA-name
                      ; The avp-spec has to be an AVP Name, defined
                      ; present in the base or extended PANA protocol
                      ; specifications.

   avp-name         = avp-spec / "AVP"
                      ; The string "AVP" stands for *any* arbitrary
                      ; AVP Name, which does not conflict with the
                      ; required or fixed position AVPs defined in
                      ; message.

   1+    At least one instance of the message definition.

   Example-Request ::= < "PANA-Header: 9999999, REQ >
                       < Session-Id >
                       { Result-Code }
                    *  [ AVP ]
                   0*1 < AUTH >

7.1.  PANA-PAA-Discover (PDI)

   The PANA-PAA-Discover (PDI) message is used to discover the address
   of PAA(s).  The sequence number in this message is always set to zero
   (0).

   PANA-PAA-Discover ::= < PANA-Header: 1 >
                       [ Notification ]
                    *  [ AVP ]

7.2.  PANA-Start-Request (PSR)

   The PANA-Start-Request (PSR) message is sent by the PAA to the PaC to
   advertise availability of the PAA and start PANA authentication.  The
   PAA sets the sequence number to an initial random value.

   PANA-Start-Request ::= < PANA-Header: 2, REQ [,SEP] [,SLS] >
                       [ Nonce ]
                       [ Cookie ]
                       [ EAP-Payload ]
                       [ NAP-Information ]
                    *  [ ISP-Information ]
                       [ Protection-Capability]
                       [ Algorithm ]
                       [ PPAC ]
                       [ Notification ]
                    *  [ AVP ]

7.3.  PANA-Start-Answer (PSA)

   The PANA-Start-Answer (PSA) message is sent by the PaC to the PAA in
   response to a PANA-Start-Request message.  This message completes the
   handshake to start PANA authentication.

   PANA-Start-Answer ::= < PANA-Header: 2 [,SEP] >
                       [ Nonce ]
                       [ Cookie ]
                       [ EAP-Payload ]
                       [ ISP-Information ]
                       [ Notification ]
                    *  [ AVP ]

7.4.  PANA-Auth-Request (PAR)

   The PANA-Auth-Request (PAR) message is either sent by the PAA or the
   PaC.  Its main task is to carry an EAP-Payload AVP.

   PANA-Auth-Request ::= < PANA-Header: 3, REQ [,SEP] [,NAP] >
                       < Session-Id >
                       < EAP-Payload >
                       [ Nonce ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.5.  PANA-Auth-Answer (PAN)

   THe PANA-Auth-Answer (PAN) message is sent by either the PaC or the
   PAA in response to a PANA-Auth-Request message.  It MAY carry an EAP-
   Payload AVP.

   PANA-Auth-Answer ::= < PANA-Header: 3 [,SEP] [,NAP] >
                       < Session-Id >
                       [ Nonce ]
                       [ EAP-Payload ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.6.  PANA-Reauth-Request (PRAR)

   The PANA-Reauth-Request (PRAR) message is sent by the PaC to the PAA
   to re-initiate EAP authentication.

   PANA-Reauth-Request ::= < PANA-Header: 4, REQ >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.7.  PANA-Reauth-Answer (PRAA)

   The PANA-Reauth-Answer (PRAA) message is sent by the PAA to the PaC
   in response to a PANA-Reauth-Request message.

   PANA-Reauth-Answer ::= < PANA-Header: 4 >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.8.  PANA-Bind-Request (PBR)

   The PANA-Bind-Request (PBR) message is sent by the PAA to the PaC to
   deliver the result of PANA authentication.

   PANA-Bind-Request ::= < PANA-Header: 5, REQ [,SEP] [,NAP] >
                       < Session-Id >
                       { Result-Code }
                       [ PPAC ]
                       [ EAP-Payload ]
                       [ Session-Lifetime ]
                       [ Protection-Capability ]
                       [ Key-Id ]
                       [ Algorithm ]
                    *  [ Device-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.9.  PANA-Bind-Answer (PBA)

   The PANA-Bind-Answer (PBA) message is sent by the PaC to the PAA in
   response to a PANA-Bind-Request message.

   PANA-Bind-Answer ::= < PANA-Header: 5 [,SEP] [,NAP] >
                       < Session-Id >
                       [ PPAC ]
                       [ Device-Id ]
                       [ Key-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.10.  PANA-Ping-Request (PPR)

   The PANA-Ping-Request (PPR) message is either sent by the PaC or the
   PAA for performing liveness test.

   PANA-Ping-Request ::= < PANA-Header: 6, REQ >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.11.  PANA-Ping-Answer (PPA)

   The PANA-Ping-Answer (PPA) message is sent in response to a PANA-
   Ping-Request.

   PANA-Ping-Answer ::= < PANA-Header: 6 >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.12.  PANA-Termination-Request (PTR)

   The PANA-Termination-Request (PTR) message is sent either by the PaC
   or the PAA to terminate a PANA session.

   PANA-Termination-Request ::= < PANA-Header: 7, REQ >
                       < Session-Id >
                       < Termination-Cause >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.13.  PANA-Termination-Answer (PTA)

   The PANA-Termination-Answer (PTA) message is sent either by the PaC
   or the PAA in response to PANA-Termination-Request.

   PANA-Termination-Answer ::= < PANA-Header: 7 >
                       < Session-Id >
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.14.  PANA-Error-Request (PER)

   The PANA-Error-Request (PER) message is sent either by the PaC or the
   PAA to report an error with the last received PANA message.

   PANA-Error-Request ::= < PANA-Header: 8, REQ >
                        < Session-Id >
                        < Result-Code >
                     *  [ Failed-AVP ]
                        [ Notification ]
                     *  [ AVP ]
                    0*1 < AUTH >

7.15.  PANA-Error-Answer (PEA)

   The PANA-Error-Answer (PEA) message is sent in response to a PANA-
   Error-Request.

   PANA-Error-Answer ::= < PANA-Header: 8 >
                        < Session-Id >
                        [ Notification ]
                     *  [ AVP ]
                    0*1 < AUTH >

7.16.  PANA-FirstAuth-End-Request (PFER)

   The PANA-FirstAuth-End-Request (PFER) message is sent by the PAA to
   the PaC to signal the result of the first EAP authentication method
   when separate NAP and ISP authentication is performed.

   PANA-FirstAuth-End-Request ::= < PANA-Header: 9, REQ [,SEP] [,NAP] >
                       < Session-Id >
                       { Result-Code }
                       [ EAP-Payload ]
                       [ Key-Id ]
                       [ Algorithm ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.17.  PANA-FirstAuth-End-Answer (PFEA)

   The PANA-FirstAuth-End-Answer (PFEA) message is sent by the PaC to
   the PAA in response to a PANA-FirstAuth-End-Request message.

   PANA-FirstAuth-End-Answer ::= < PANA-Header: 9, REQ [,SEP] [,NAP] >
                       < Session-Id >
                       [ Key-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.18.  PANA-Update-Request (PUR)

   The PANA-Update-Request (PUR) message is sent either by the PaC or
   the PAA to deliver attribute updates and notifications.  In the scope
   of this specification only the IP address and device identifer of the
   PaC can be updated via this message.

   PANA-Update-Request ::= < PANA-Header: 10, REQ >
                       < Session-Id >
                       [ Device-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

7.19.  PANA-Update-Answer (PUA)

   The PANA-Update-Answer (PUA) message is sent by the PAA (PaC) to the
   PaC (PAA) in response to a PANA-Update-Request from the PaC (PAA).

   PANA-Update-Answer ::= < PANA-Header: 10 >
                       < Session-Id >
                    *  [ Device-Id ]
                       [ Notification ]
                    *  [ AVP ]
                   0*1 < AUTH >

8.  AVPs in PANA

   PANA defines several AVPs that are specific to the protocol.  A
   number of others AVPs are reused.  These are specified in other
   documents such as [RFC3588].

   The following tables lists the AVPs used in this document, and
   specifies in which PANA messages they MAY, or MAY NOT be present.

   The table uses the following symbols:

   0     The AVP MUST NOT be present in the message.

   0+    Zero or more instances of the AVP MAY be present in the
         message.

   0-1   Zero or one instance of the AVP MAY be present in the message.
         It is considered an error if there are more than one instance
         of the AVP.

   1     One instance of the AVP MUST be present in the message.

   1+    At least one instance of the AVP MUST be present MUST be present in the
         message.

                         +---------------------------------------------+
                         |                 Message                    |
                         | Type                |
                         +---+---+---+---+---+----+----+---+---+---+---+
   Attribute Name        |PDI|PSR|PSA|PAR|PAN|PRAR|PRAA|PBR|PBA|PPR|PPA|        |PCI|PSR|PSA|PAR|PAN|PRAR|PRAA|PBR|PBA|PPR|PPA|
   ----------------------+---+---+---+---+---+----+----+---+---+---+---+
   Algorithm             | 0 |0-1| 0 | 0 | 0 | 0  | 0  |0-1| 0 | 0 | 0 |
   AUTH                  | 0 | 0 | 0 |0-1|0-1|0-1 |0-1 |0-1|0-1|0-1|0-1|
   Cookie                | 0 |0-1|0-1| 0 | 0 | 0  | 0  | 0 | 0 | 0 | 0 |
   Device-Id             | 0 | 0 | 0 | 0 | 0 | 0  | 0  | 0+|0-1| 0 | 0 |
   EAP-Payload           | 0 |0-1|0-1| 1 |0-1| 0  | 0  |0-1| 0 | 0 | 0 |
   Failed-AVP            | 0 | 0 | 0 | 0 | 0 | 0  | 0  | 0 | 0 | 0 | 0 |
   ISP-Information       | 0 | 0+|0-1| 0 | 0 | 0  | 0  | 0 | 0 | 0 | 0 |
   Key-Id                | 0 | 0 | 0 | 0 | 0 | 0  | 0  |0-1|0-1| 0 | 0 |
   NAP-Information       | 0 |0-1| 0 | 0 | 0 | 0  | 0  | 0 | 0 | 0 | 0 |
   Nonce                 | 0 |0-1|0-1|0-1|0-1| 0  | 0  | 0 | 0 | 0 | 0 |
   Notification          |0-1|0-1|0-1|0-1|0-1|0-1 |0-1 |0-1|0-1|0-1|0-1|
   PPAC                  | 0 |0-1| 0 | 0 | 0 | 0  | 0  |0-1|0-1| 0 | 0 |
   Protection-Capability | 0 |0-1| 0 | 0 | 0 | 0  | 0  |0-1| 0 | 0 | 0 |
   Result-Code           | 0 | 0 | 0 | 0 | 0 | 0  | 0  | 1 | 0 | 0 | 0 |
   Session-Id            | 0 | 0 | 0 | 1 | 1 | 1  | 1  | 1 | 1 | 1 | 1 |
   Session-Lifetime      | 0 | 0 | 0 | 0 | 0 | 0  | 0  |0-1| 0 | 0 | 0 |
   Termination-Cause     | 0 | 0 | 0 | 0 | 0 | 0  | 0  | 0 | 0 | 0 | 0 |
   ----------------------+---+---+---+---+---+----+----+---+---+---+---+

   Figure 10: 9: AVP Occurrence Table (1/2)
                         +---------------------------------+
                         +-----------------------+
                         |     Message            |
                         | Type      |
                         +---+---+---+---+----+----+---+---+
                         +---+---+---+---+---+---+
   Attribute Name        |PTR|PTA|PER|PEA|PFER|PFEA|PUR|PUA|
   ----------------------+---+---+---+---+----+----+---+---+        |PTR|PTA|PER|PEA|PUR|PUA|
   ----------------------+---+---+---+---+---+---+
   Algorithm             | 0 | 0 | 0 | 0 |0-1 | 0 | 0 | 0 |
   AUTH                  |0-1|0-1|0-1|0-1|0-1 |0-1 |0-1|0-1|                  |0-1|0-1|0-1|0-1|0-1|0-1|
   Cookie                | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Device-Id             | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   EAP-Payload           | 0 | 0 | 0 | 0 |0-1 | 0 | 0 | 0 |
   Failed-AVP            | 0 | 0 | 0+| 0 | 0 | 0 | 0 | 0 |
   ISP-Information       | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Key-Id                | 0 | 0 | 0 | 0 |0-1 |0-1 | 0 | 0 |
   NAP-Information       | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Nonce                 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Notification          |0-1|0-1|0-1|0-1|0-1 |0-1 |0-1|0-1|          |0-1|0-1|0-1|0-1|0-1|0-1|
   PPAC                  | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Protection-Capability | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Result-Code           | 0 | 0 | 1 | 0 | 1  | 0  | 0 | 0 |
   Session-Id            | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
   Session-Lifetime      | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   Termination-Cause     | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
   ----------------------+---+---+---+---+----+----+---+---+
   ----------------------+---+---+---+---+---+---+

   Figure 11: 10: AVP Occurrence Table (2/2)

8.1.  Algorithm AVP

   The Algorithm AVP (AVP Code 1) is used for conveying the pseudo-
   random function to derive PANA_AUTH_KEY and PaC-EP-Master-Key as well
   as the integrity algorithm to compute an AUTH AVP.  The AVP data is
   of type Unsigned32.

   The first 16-bit of the AVP data contains an IKEv2 Transform ID of
   Transform Type 2 [RFC4306] corresponding to the key derivation
   function.

   The last 16-bit of the AVP data contains an IKEv2 Transform ID of
   Transform Type 3 [RFC4306] for the integrity algorithm.

   All PANA implementations MUST support PRF_HMAC_SHA1 (2) [RFC2104] for
   the key derivation algorithm and AUTH_HMAC_SHA1_160 (7) [ianaweb]
   corresponding to the integrity algorithm.

8.2.  AUTH AVP

   The AUTH AVP (AVP Code 2) is used to integrity protect PANA messages.
   The AVP data payload contains the Message Authentication Code encoded
   in network byte order.  The AVP length varies depending on the
   integrity algorithm specified in an Algorithm AVP.

8.3.  Cookie AVP

   The Cookie AVP (AVP Code 3) is used for carrying a random value
   generated by the PAA according to [RFC4086].  The AVP data is of type
   OctetString.  The random value is referred to as a cookie and used
   for making PAA discovery the handshake phase robust against blind resource
   consumption DoS attacks.  The exact algorithms and syntax used by the
   PAA to generate a cookie does not affect interoperability and not
   specified in this document.  An example cookie generation algorithm is shown in
   Section 4.3.

8.4.  Device-Id AVP

   The Device-Id AVP (AVP Code 4) is used for carrying device
   identifiers of PaC and EP(s).  The AVP data is of Address type
   [RFC3588].  IPv4 and IPv6 addresses are encoded as specified in
   [RFC3588].  The content and format of data (including byte and bit
   ordering) for link-layer addresses is expected to be specified in
   specific documents that describe how IP operates over different link-
   layers.  For instance, [RFC2464].  Address families other than that
   are defined for link-layer or IP addresses MUST NOT be used for this
   AVP.

8.5.  EAP-Payload AVP

   The EAP-Payload AVP (AVP Code 5) is used for encapsulating the actual
   EAP message that is being exchanged between the EAP peer and the EAP
   authenticator.  The AVP data is of type OctetString.

8.6.  Failed-AVP AVP

   The Failed-AVP AVP (AVP Code 6) provides debugging information in
   cases where a request is rejected or not fully processed due to
   erroneous information in a specific AVP.  The AVP data is of type
   Grouped.  The format of the Failed-AVP AVP is defined in [RFC3588].
   In case of a failed grouped AVP, the Failed-AVP contains the whole
   grouped AVP.  In case of a failed AVP inside a grouped AVP, the
   Failed-AVP contains the single offending AVP.

8.7.  ISP-Information AVP

   The ISP-Information AVP (AVP Code 7) contains zero or one Provider-
   Identifier AVP which carries the identifier of the ISP and one
   Provider-Name AVP which carries the name of the ISP.  The AVP data is
   of type Grouped, and it has the following ABNF grammar:

   ISP-Information ::= < AVP Header: 7 >
                    0*1 { Provider-Identifier }
                        { Provider-Name }
                     *  [ AVP ]

8.8.  Key-Id AVP

   The Key-Id AVP (AVP Code 8) is of type Integer32, and contains an
   AAA-Key MSK
   identifier.  The AAA-Key MSK identifier is assigned by PAA and MUST be unique
   within the PANA session.

8.9.  NAP-Information AVP

   The NAP-Information AVP (AVP Code 9) contains zero or one Provider-
   Identifier AVP which carries the identifier of the NAP and one
   Provider-Name AVP which carries the name of the NAP.  The AVP data is
   of type Grouped, and it has the following ABNF grammar:

   NAP-Information ::= < AVP Header: 9 >
                    0*1 { Provider-Identifier }
                        { Provider-Name }
                     *  [ AVP ]

8.10.  Nonce AVP

   The Nonce AVP (AVP Code 10) carries a randomly chosen value that is
   used in cryptographic key computations.  The recommendations in
   [RFC4086] apply with regard to generation of random values.  The AVP
   data is of type OctetString and it contains a randomly generated
   value in opaque format.  The data length MUST be between 8 and 256
   octets inclusive.

   The length of the nonces are determined based on the available
   pseudo-random functions (PRFs) and the degree of trust placed into
   the two PaC and the PAA to compute random values.  The length of the
   random value for the nonce is determined whether

   1.  The PaC and the PAA each are likely to be able to compute a
       random nonce (according to [RFC4086]).  The length of the nonce
       has to be 1/2 the length of the PRF key (e.g., 10 octets in the
       case of HMAC-SHA1).

   2.  The PaC and the PAA each are not trusted with regard to the
       computation a random nonce (according to [RFC4086]).  The length
       of the nonce has to have the full length of the PRF key (e.g., 20
       octets in the case of HMAC-SHA1).

   Furthermore, the strongest available PRF available for PANA has to be
   considered in this computation.  Currently, only a single PRF (namely
   HMAC-SHA1) is available and therefore the maximum output length is 20
   octets).  The recommended maximum length of the nonce value is
   therefore currently 20 octets.

8.11.  Notification AVP

   The Notification AVP (AVP Code 11) is optionally used to convey a
   displayable message sent by either the PaC or the PAA.  It can be
   included in any message, whether it is a request or answer.  In case
   a notification needs to be sent but there is no outgoing PANA message
   to deliver this AVP, a PANA-Update-Request that only carries a
   Notification AVP SHOULD be generated.

   The 'M' bit in the AVP header of this AVP MUST NOT be set.

   Receipt this AVP does not change PANA state.

   AVP data is of type OctetString and it contains the following fields
   in the listed order:

   Language Tag Length

      This field contains the length of the Language Tag in octets.  The
      length of this field is 2 octets.

   Language Tag

      This field contains the language tag defined in [I-D.ietf-ltru-
      registry] to indicate the language used for Displayable String.
      The length of this data is determined by the Language Tag Length
      field.

   Displayable String

      This field contains UTF-8 encoded ISO 10646 characters [RFC2279]
      using the language indicated by the Language Tag. The length of
      this data is determined by the AVP Length field and the Language
      Tag Length field.  This data MUST NOT be null terminated.

8.12.  Post-PANA-Address-Configuration (PPAC) AVP

   The PPAC AVP (AVP Code 12) is used for conveying the available types
   of post-PANA IP address configuration mechanisms when sent by the
   PAA, and the chosen one when sent by the PaC.  Each possible
   mechanisms is represented by a flag.  The AVP data is of type
   Unsigned32.

   The format of the AVP data is as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |N|F|S|A|T|I|                    Reserved                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   PPAC Flags

      N (No configuration)

         The PaC does not have to (if sent by PAA) or will not (if sent
         by PaC) configure a new IP address after PANA.

      F (DHCPv4)

         The PaC can (if sent by PAA) or will (if sent by PaC) use
         DHCPv4 [RFC2131] to configure a new IPv4 address after PANA.

      S (DHCPv6)

         The PaC can (if sent by PAA) or will (if sent by PaC) use
         DHCPv6 [RFC3315] to configure a new IPv4 IPv6 address after PANA.

      A (stateless autoconfiguration)

         The PaC can/will use stateless IPv6 address autoconfiguration
         [RFC2462] to configure a new IPv6 address after PANA.

      T (DHCPv4 with IPsec tunnel mode)

         The PaC can/will use [RFC3456] to configure a new IPv4 address
         after PANA.

      I (IKEv2)

         The PaC can/will use [RFC4306] to configure (a) new IPv4 and/or
         IPv6 address(es) after PANA.

      Reserved

         These flag bits are reserved for future use, and MUST be set to
         zero, and ignored by the receiver.

   The PAA MUST set either the N-flag, or one or more of the other
   flags.  If the N-flag is set, the PaC MUST only set its N-flag in its
   response.  If the N-flag is not set by the PAA, that means the PaC
   MUST configure POPA(s) using the method(s) indicated by the flags.
   If IPsec-based access control is not used, the F-flag, S-flag or
   A-flag MUST be set by the PAA, and the PaC MUST echo the same flag(s)
   in its response.  Refer to [I-D.ietf-pana-framework] for a detailed
   discussion on when these methods can be used.

8.13.  Protection-Capability AVP

   The Protection-Capability AVP (AVP Code 13) indicates the
   cryptographic data protection capability supported and required by
   the EPs.  The AVP data is of type Unsigned32.  Below is a list of
   valid data values and associated protection capabilities:

      0          L2_PROTECTION
      1          IPSEC_PROTECTION

8.14.  Provider-Identifier AVP

   The Provider-Identifier AVP (AVP Code 14) is of type Unsigned32, and
   contains an IANA assigned "SMI Network Management Private Enterprise
   Codes" [ianaweb] value, encoded in network byte order.

8.15.  Provider-Name AVP

   The Provider-Name AVP (AVP Code 15) is of type UTF8String, and
   contains the UTF8-encoded name of the provider.

8.16.  Result-Code AVP

   The Result-Code AVP (AVP Code 16) is of type Unsigned32 and indicates
   whether an EAP authentication was completed successfully or whether
   an error occurred.  Here are Result-Code AVP values taken from
   [RFC3588] and adapted for PANA.

8.16.1.  Authentication Results Codes

   These result code values inform the PaC about the authentication and
   authorization result.  The authentication result and authorization
   result can be different as described below, but only one result is
   returned to the PaC.  These codes are used with PANA-Bind-Request and
   PANA-FirstAuth-End-Request messages.
   message.

   PANA_SUCCESS                            2001

      Both authentication and authorization processes are successful.

   PANA_AUTHENTICATION_REJECTED            4001

      Authentication has failed.  When this error is returned, it is
      assumed that authorization is automatically failed.

   PANA_AUTHORIZATION_REJECTED             5003

      The authorization process has failed.  This error could occur when
      authorization is rejected by a AAA server or rejected locally by a
      PAA, even if the authentication procedure has succeeded.

8.16.2.  Protocol Error Result Codes

   These codes are used with PANA-Error-Request messages.  Unless stated
   otherwise, they can be generated by both the PaC and the PAA.

   PANA_MESSAGE_UNSUPPORTED                3001

      Message type not recognized or supported.

   PANA_UNABLE_TO_DELIVER                  3002

      The PAA was unable to deliver the EAP payload to the
      authentication server.  Only the PAA can generate this code.

   PANA_INVALID_HDR_BITS                   3008

      A message was received whose bits in the PANA header were either
      set to an invalid combination, or to a value that is inconsistent
      with the message type definition.

   PANA_INVALID_AVP_FLAGS                   3009

      A message was received that included an AVP whose flag bits are
      set to an unrecognized value, or that is inconsistent with the
      AVP's definition.

   PANA_AVP_UNSUPPORTED                    5001

      The received message contained an AVP that is not recognized or
      supported and was marked with the Mandatory bit.  A PANA message
      with this error MUST contain one or more Failed-AVP AVP containing
      the AVPs that caused the failure.

   PANA_UNKNOWN_SESSION_ID                 5002
      The message contained an unknown Session-Id.  A PANA message
      indicating this error MUST include the unknown Session-Id AVP
      within a Failed-AVP AVP.

   PANA_INVALID_AVP_DATA                   5004

      The message contained an AVP with an invalid value in its data
      portion.  A PANA message indicating this error MUST include the
      offending AVPs within a Failed-AVP AVP.

   PANA_MISSING_AVP                        5005

      The message did not contain an AVP that is required by the message
      type definition.  If this value is sent in the Result-Code AVP, a
      Failed-AVP AVP SHOULD be included in the message.  The Failed-AVP
      AVP MUST contain an example of the missing AVP complete with the
      Vendor-Id if applicable.  The value field of the missing AVP
      should be of correct minimum length and contain zeroes.

   PANA_RESOURCES_EXCEEDED                 5006

      A message was received that cannot be authorized because the
      client has already expended allowed resources.  An example of this
      error condition is a client that is restricted to one PANA session
      and attempts to establish a second session.  Only the PAA can
      generate this code.

   PANA_CONTRADICTING_AVPS                 5007

      The PAA has detected AVPs in the message that contradicted each
      other, and is not willing to provide service to the client.  One
      or more Failed-AVP AVPs MUST be present, containing the AVPs that
      contradicted each other.  Only the PAA can generate this code.

   PANA_AVP_NOT_ALLOWED                    5008

      A message was received with an AVP that MUST NOT be present.  The
      Failed-AVP AVP MUST be included and contain a copy of the
      offending AVP.

   PANA_AVP_OCCURS_TOO_MANY_TIMES          5009

      A message was received that included an AVP that appeared more
      often than permitted in the message definition.  The Failed-AVP
      AVP MUST be included and contain a copy of the first instance of
      the offending AVP that exceeded the maximum number of occurrences.

   PANA_UNSUPPORTED_VERSION                5011

      This error is returned when a message was received, whose version
      number is unsupported.

   PANA_UNABLE_TO_COMPLY                   5012

      This error is returned when a request is rejected for unspecified
      reasons.  For example, when an EAP authentication fails at an EAP
      pass-through authenticator without passing an EAP Failure message
      to the PAA, a Result-Code AVP with this error code is carried in
      the PANA-Error-Request message.

   PANA_INVALID_AVP_LENGTH                 5014

      The message contained an AVP with an invalid length.  The PANA-
      Error-Request message indicating this error MUST include the
      offending AVPs within a Failed-AVP AVP.

   PANA_INVALID_MESSAGE_LENGTH             5015

      This error is returned when a message is received with an invalid
      message length.

   PANA_PROTECTION_CAPABILITY_UNSUPPORTED  5016

      This error is returned when the PaC receives a PANA-Bind-Request
      message with a Protection-Capability AVP and a valid AUTH AVP but
      does not support the protection capability specified in the
      Protection-Capability AVP.  Only the PaC can generate this code.

   PANA_PPAC_CAPABILITY_UNSUPPORTED  5017

      This error is returned when there is no match between the list of
      PPAC methods offered by the PAA and the ones available on the PaC.
      Only the PaC can generate this code.

8.17.  Session-Id AVP

   All messages pertaining to a specific PANA session MUST include a
   Session-Id AVP (AVP Code 17) which carries a PAA-assigned fixed
   session identifier value throughout the lifetime of a session.  When
   present, the Session-Id AVP MUST appear immediately following the
   PANA header.

   The Session-Id MUST be globally and eternally unique, as it is meant
   to identify a PANA session without reference to any other
   information, and may be needed to correlate historical authentication
   information with accounting information.  The PANA Session-Id AVP has
   the same format as the Diameter Session-Id AVP [RFC3588].

8.18.  Session-Lifetime AVP

   The Session-Lifetime AVP (AVP Code 18) contains the number of seconds
   remaining before the current session is considered expired.  The AVP
   data is of type Unsigned32.

8.19.  Termination-Cause AVP

   The Termination-Cause AVP (AVP Code 19) is used for indicating the
   reason why a session is terminated by the requester.  The AVP data is
   of type Enumerated.  The following Termination-Cause data values are
   used with PANA.

   LOGOUT                   1  (PaC -> PAA)

      The client initiated a disconnect

   ADMINISTRATIVE           4  (PAA -> PaC)

      The client was not granted access, or was disconnected, due to
      administrative reasons.

   SESSION_TIMEOUT          8  (PAA -> PaC)

      The session has timed out, and service has been terminated.

9.  Retransmission Timers

   The PANA protocol provides retransmissions for the PANA-PAA-Discover PANA-Client-
   Initiation message and all request messages, with the exception that
   the PANA-
   Start-Answer PANA-Start-Answer message is retransmitted instead of the PANA-Start-
   Request PANA-
   Start-Request message in stateless PAA discovery. handshake.

   PANA retransmission timers are based on the model used in DHCPv6
   [RFC3315].  Variables used here are also borrowed from this
   specification.  PANA is a request response like protocol.  The
   message exchange terminates when either the request sender
   successfully receives the appropriate answer, or when the message
   exchange is considered to have failed according to the retransmission
   mechanism described below.

   The retransmission behavior is controlled and described by the
   following variables:

         RT     Retransmission timeout

         IRT    Initial retransmission time

         MRC    Maximum retransmission count

         MRT    Maximum retransmission time

         MRD    Maximum retransmission duration

         RAND   Randomization factor

   With each message transmission or retransmission, the sender sets RT
   according to the rules given below.  If RT expires before the message
   exchange terminates, the sender recomputes RT and retransmits the
   message.

   Each of the computations of a new RT include a randomization factor
   (RAND), which is a random number chosen with a uniform distribution
   between -0.1 and +0.1.  The randomization factor is included to
   minimize synchronization of messages.

   The algorithm for choosing a random number does not need to be
   cryptographically sound.  The algorithm SHOULD produce a different
   sequence of random numbers from each invocation.

   RT for the first message transmission is based on IRT:

         RT = IRT + RAND*IRT
   RT for each subsequent message transmission is based on the previous
   value of RT:

         RT = 2*RTprev + RAND*RTprev

   MRT specifies an upper bound on the value of RT (disregarding the
   randomization added by the use of RAND).  If MRT has a value of 0,
   there is no upper limit on the value of RT.  Otherwise:

         if (RT > MRT)
            RT = MRT + RAND*MRT

   MRC specifies an upper bound on the number of times a sender may
   retransmit a message.  Unless MRC is zero, the message exchange fails
   once the sender has transmitted the message MRC times.

   MRD specifies an upper bound on the length of time a sender may
   retransmit a message.  Unless MRD is zero, the message exchange fails
   once MRD seconds have elapsed since the client first transmitted the
   message.

   If both MRC and MRD are non-zero, the message exchange fails whenever
   either of the conditions specified in the previous two paragraphs are
   met.

   If both MRC and MRD are zero, the client continues to transmit the
   message until it receives a response.

9.1.  Transmission and Retransmission Parameters

   This section presents a table of values used to describe the message
   retransmission behavior of PANA requests and answers that are
   retransmitted (REQ_*) and PANA-PAA-Discover PANA-Client-Initiation message (PDI_*). (PCI_*).
   The table shows default values.

           Parameter       Default   Description
           ------------------------------------------------
           PDI_IRT
           PCI_IRT           1 sec   Initial PDI PCI timeout.
           PDI_MRT
           PCI_MRT         120 secs  Max PDI PCI timeout value.
           PDI_MRC
           PCI_MRC           0       Configurable.
           PDI_MRD
           PCI_MRD           0       Configurable.

           REQ_IRT           1 sec   Initial Request timeout.
           REQ_MRT          30 secs  Max Request timeout value.
           REQ_MRC          10       Max Request retry attempts.
           REQ_MRD           0       Configurable.

   So for example the first RT for the PBR message is calculated using
   REQ_IRT as the IRT:

           RT = REQ_IRT + RAND*REQ_IRT

10.  IANA Considerations

   This section provides guidance to the Internet Assigned Numbers
   Authority (IANA) regarding registration of values related to the PANA
   protocol, in accordance with BCP 26 [IANA].  The following policies
   are used here with the meanings defined in BCP 26: "Private Use",
   "First Come First Served", "Expert Review", "Specification Required",
   "IETF Consensus", "Standards Action".

   This section explains the criteria to be used by the IANA for
   assignment of numbers within namespaces defined within this document.

   For registration requests where a Designated Expert should be
   consulted, the responsible IESG area director should appoint the
   Designated Expert.  For Designated Expert with Specification
   Required, the request is posted to the PANA WG mailing list (or, if
   it has been disbanded, a successor designated by the Area Director)
   for comment and review, and MUST include a pointer to a public
   specification.  Before a period of 30 days has passed, the Designated
   Expert will either approve or deny the registration request and
   publish a notice of the decision to the PANA WG mailing list or its
   successor.  A denial notice must be justified by an explanation and,
   in the cases where it is possible, concrete suggestions on how the
   request can be modified so as to become acceptable.

10.1.  PANA UDP Port Number

   PANA uses one well-known UDP port number (Section 4.1, Section 4.3
   and Section 6.1), which needs to be assigned by the IANA.

10.2.  PANA Multicast Address Header

   As defined in Section 6.2, the PANA uses one well-known administratively scoped IPv4 multicast
   address, and one well-known administratively scoped IPv6 multicast
   address (Section 4.3 header contains two fields that
   requires IANA namespace management; the Message Type and Section 6.1), which need Flags field.

10.2.1.  Message Type

   The Message Type namespace is used to identify PANA messages.  Values
   0-65,533 are for permanent, standard message types, allocated by IETF
   Consensus [IANA].  This document defines the Message Types 1-9.  See
   Section 7.1 through Section 7.17 for the assignment of the namespace
   in this specification.

   The values 65,534 and 65,535 (hexadecimal values 0xfffe - 0xffff) are
   reserved for experimental messages.  As these codes are only for
   experimental and testing purposes, no guarantee is made for
   interoperability between the communicating PaC and PAA using
   experimental commands, as outlined in [IANA-EXP].

10.2.2.  Flags

   There are 16 bits in the Flags field of the PANA header.  This
   document assigns bit 0 ('R'equest), bit 1 (state'L'ess handshake).
   The remaining bits MUST only be assigned by
   the IANA. via a Standards Action
   [IANA].

10.3.  PANA  AVP Header

   As defined in Section 6.2, 6.3, the PANA AVP header contains two three fields that
   requires IANA namespace management; the Message Type AVP Code, AVP Flags and
   Vendor-Id fields where only the AVP Code and AVP Flags field. create new
   namespaces.

10.3.1.  Message Type  AVP Code

   The Message Type AVP Code namespace is used to identify PANA messages.  Values
   0-65,533 attributes.  There are for permanent, standard message types, allocated
   multiple namespaces.  Vendors can have their own AVP Codes namespace
   which will be identified by their Vendor-ID (also known as
   Enterprise-Number) and they control the assignments of their vendor-
   specific AVP codes within their own namespace.  The absence of a
   Vendor-ID or a Vendor-ID value of zero (0) identifies the IETF
   Consensus [IANA]. IANA
   controlled AVP Codes namespace.  The AVP Codes and sometimes also
   possible values in an AVP are controlled and maintained by IANA.

   AVP Code 0 is not used.  This document defines the Message Types 1-10. AVP Codes 1-19.
   See Section 7.1 8.1 through Section 7.19 8.19 for the assignment of the
   namespace in this specification.

   The values 65,534 and 65,535 (hexadecimal values 0xfffe - 0xffff) are
   reserved

   AVPs may be allocated following Designated Expert with Specification
   Required [IANA].  Release of blocks of AVPs (more than 3 at a time
   for experimental messages.  As these a given purpose) should require IETF Consensus.

   Note that PANA defines a mechanism for Vendor-Specific AVPs, where
   the Vendor-Id field in the AVP header is set to a non-zero value.
   Vendor-Specific AVPs codes are only for
   experimental Private Use and testing purposes, should be
   encouraged instead of allocation of global attribute types, for
   functions specific only to one vendor's implementation of PANA, where
   no guarantee is made for interoperability between the communicating PaC and PAA using
   experimental commands, as outlined in [IANA-EXP]. is deemed useful.  Where a Vendor-Specific AVP is
   implemented by more than one vendor, allocation of global AVPs should
   be encouraged instead.

10.3.2.  Flags

   There are 16 bits in the AVP Flags field of the PANA header. AVP header, defined
   in Section 6.3.  This document assigns bit 0 ('R'equest), bit 1 ('S'eparate) ('V'endor Specific) and
   bit 2
   ('N'AP Authentication). 1 ('M'andatory).  The remaining bits MUST should only be assigned via
   a Standards Action [IANA]. .

10.4.  AVP Header Values

   Certain AVPs in PANA define a list of values with various meanings.
   For attributes other than those specified in this section, adding
   additional values to the list can be done on a First Come, First
   Served basis by IANA [IANA].

10.4.1.  Post-PANA-Address-Configuration AVP Values

   As defined in Section 6.3, 8.12, the Post-PANA-Address-Configuration AVP header contains three fields that
   requires IANA namespace management;
   (AVP Code 12) defines the AVP Code, AVP Flags bits 0 ('N': no configuration), 1 ('F':
   DHCPv4), 2 ('S': DHCPv6), 3 ('A' stateless autoconfiguration), 4
   ('T': DHCPv4 with IPsec tunnel mode) and
   Vendor-Id fields where only 5 ('I': IKEv2).

   All remaining values are available for assignment via a Standards
   Action [IANA].

10.4.2.  Protection-Capability AVP Values

   As defined in Section 8.13, the Protection-Capability AVP (AVP Code
   13) defines the values 0 and 1.

   All remaining values are available for assignment via a Standards
   Action [IANA].

10.4.3.  Result-Code AVP Flags create new
   namespaces.

10.4.1.  AVP Code

   The Values

   As defined in Section 8.16.1 and Section 8.16.2 the Result-Code AVP
   (AVP Code namespace is used to identify attributes.  There are
   multiple namespaces.  Vendors can have their own AVP Codes namespace
   which will be identified by their Vendor-ID (also known as
   Enterprise-Number) 16) defines the values 2001, 3001-3002, 3008-3009, 4001,
   5001-5009 and they control 5011-5017.

   All remaining values are available for assignment via IETF Consensus
   [IANA].

10.4.4.  Termination-Cause AVP Values

   As defined in Section 8.19, the assignments of their vendor-
   specific Termination-Cause AVP codes within their own namespace. (AVP Code 19)
   defines the values 1, 4 and 8.

   All remaining values are available for assignment via IETF Consensus
   [IANA].

11.  Security Considerations

   The absence of PANA protocol defines a
   Vendor-ID or UDP-based EAP encapsulation that runs
   between two IP-enabled nodes on the same IP link.  Various security
   threats that are relevant to a Vendor-ID value protocol of zero (0) identifies this nature are outlined
   in [RFC4016].  Security considerations stemming from the IETF IANA
   controlled AVP Codes namespace.  The AVP Codes use of EAP
   and sometimes also
   possible values EAP methods are discussed in an AVP [RFC3748] [I-D.ietf-eap-keying].
   This section provides a discussion on the security-related issues
   that are controlled related to PANA framework and maintained by IANA.

   AVP Code 0 protocol design.

   An important element in assessing security of PANA design and
   deployment in a network is not used.  This document defines the AVP Codes 1-19.
   See Section 8.1 through Section 8.19 for the assignment presence of lower-layer (physical and
   link-layer) security.  In the
   namespace in context of this specification.

   AVPs may document, lower-layers
   are said to be allocated following Designated Expert with Specification
   Required [IANA].  Release secure if they can prevent eavesdropping and spoofing
   of blocks packets.  Examples of AVPs (more than 3 at a time
   for such networks are physically-secured DSL
   networks and 3GPP2 networks with cryptographically-secured cdma2000
   link-layer.  In these examples, the lower-layer security is enabled
   even before running the first PANA-based authentication.  In the
   absence of such a given purpose) should require IETF Consensus.

   Note that pre-established secure channel, one needs to be
   created in conjunction with PANA defines using a link-layer or network-layer
   cryptographic mechanism for Vendor-Specific AVPs, where
   the Vendor-Id field in the AVP header is set (e.g., IPsec).

11.1.  General Security Measures

   PANA provides multiple mechanisms to secure a non-zero value.
   Vendor-Specific AVPs codes PANA session.

   PANA messages carry sequence numbers, which are for Private Use and should be
   encouraged instead of allocation of global attribute types, for
   functions specific only to one vendor's implementation monotonically
   incremented by 1 with every new request message.  These numbers are
   randomly initialized at the beginning of PANA, where
   no interoperability is deemed useful.  Where a Vendor-Specific AVP the session, and verified
   against expected numbers upon receipt.  A message whose sequence
   number is
   implemented by more different than the expected one vendor, allocation is silently discarded.  In
   addition to accomplishing orderly delivery of global AVPs should
   be encouraged instead.

10.4.2.  Flags

   There are 16 bits in EAP messages and
   duplicate elimination, this scheme also helps prevent an adversary
   spoof messages to disturb ongoing PANA and EAP sessions unless it can
   also eavesdrop to synchronize on the AVP Flags field expected sequence number.
   Furthermore, impact of the AVP header, defined
   in Section 6.3.  This document assigns bit 0 ('V'endor Specific) and
   bit 1 ('M'andatory).  The remaining bits should only be assigned via replay attacks is reduced as any stale message
   (i.e., a Standards Action .

10.5.  AVP Values

   Certain AVPs in PANA define request or answer with an unexpected sequence number) and
   any duplicate answer are immediately discarded, and a list duplicate
   request can trigger transmission of values with various meanings.
   For attributes other than those specified in this section, adding
   additional values the cached answer (i.e., no need
   to process the list can be done request and generate a new answer).

   The PANA framework defines EP which is ideally located on a First Come, First
   Served basis by IANA [IANA].

10.5.1.  Post-PANA-Address-Configuration AVP Values

   As defined in Section 8.12, network
   device that can filter traffic from the Post-PANA-Address-Configuration AVP
   (AVP Code 12) defines PaCs before the bits 0 ('N': no configuration), 1 ('F':
   DHCPv4), 2 ('S': DHCPv6), 3 ('A' stateless autoconfiguration), 4
   ('T': DHCPv4 with IPsec tunnel mode) and 5 ('I': IKEv2).

   All remaining values are available for assignment via traffic
   enters the Internet/intranet.  A set of filters can be used to
   discard unauthorized packets, such as a Standards
   Action [IANA].

10.5.2.  Protection-Capability AVP Values

   As defined in Section 8.13, PANA-Start-Request message
   that is received from the Protection-Capability AVP (AVP Code
   13) defines segment of the values 0 and 1.

   All remaining values access network where only
   the PaCs are available for assignment via a Standards
   Action [IANA].

10.5.3.  Result-Code AVP Values

   As defined in Section 8.16.1 supposed to be connected.

   The protocol also provides authentication and Section 8.16.2 integrity protection to
   PANA messages when the Result-Code AVP
   (AVP Code 16) defines used EAP method can generate cryptographic
   session keys.  A PANA SA is generated based on the values 2001, 3001-3002, 3008-3009, 4001,
   5001-5009 and 5011-5017.

   All remaining values are available for assignment via IETF Consensus
   [IANA].

10.5.4.  Termination-Cause AVP Values

   As defined in Section 8.19, MSK exported by
   the Termination-Cause EAP method.  This SA is used for generating an AUTH AVP (AVP Code 19)
   defines to
   protect the values 1, 4 PANA header and 8.

   All remaining values are available for assignment via IETF Consensus
   [IANA].

11.  Security Considerations payload (including the complete EAP
   message).

   The PANA protocol defines cryptographic protection prevents an adversary from acting as a UDP-based EAP encapsulation that runs
   between two IP-enabled nodes on
   man-in-the-middle, injecting messages, replaying messages and
   modifying the same IP link.  Various security
   threats content of the exchanged messages.  Any packet that are relevant
   fails to a protocol of pass the AUTH verification is silently discarded.  The
   earliest this nature are outlined
   in [RFC4016].  Security considerations stemming from protection can be enabled is when the use very first PANA-
   Bind-Request message that signals a successful authentication is
   generated.  Starting with these messages, any subsequent PANA message
   until the session gets torn down can be cryptographically protected.

   The PANA SA enables authenticated and integrity protected exchange of EAP
   the device ID information between the PaC and EAP methods are discussed in [RFC3748] [I-D.ietf-eap-keying]. PAA.  This section provides a discussion on ensures
   there were no man-in-the-middle during the security-related issues
   that are related to PANA framework and protocol design.

   An important element in assessing security authentication.

   The lifetime of the PANA design and
   deployment in SA is set to PANA session lifetime which is
   bounded by the authorization lifetime granted by the authentication
   server.  An implementation MAY add a network tolerance period to that value.
   Unless the PANA session is extended by executing another EAP
   authentication, the PANA SA is removed when the current session
   expires.

   The ability to use cryptographic protection within PANA is determined
   by the presence of lower-layer (physical and
   link-layer) security.  In used EAP method, which is generally dictated by the context deployment
   environment.  Insecure lower-layers necessitate use of this document, key-generating
   EAP methods.  In networks where lower-layers are said already secured,
   cryptographic protection of PANA messages is not necessary.

11.2.  Handshake

   The handshake phase is vulnerable to be secure if they can prevent eavesdropping and spoofing
   of packets.  Examples of such networks attacks as these
   messages are physically-secured DSL
   networks not authenticated and 3GPP2 networks with cryptographically-secured cdma2000
   link-layer. integrity protected.  In these examples, order to
   prevent very basic denial-of service attacks an adversary should not
   be able to cause state creation by sending PANA-Client-Initiation
   messages to the lower-layer security PAA.  This protection is enabled
   even before running the first PANA-based authentication.  In the
   absence of such achieved by using a pre-established secure channel, one needs cookie-
   based scheme (similar to [RFC2522] which allows the responder (PAA)
   to be
   created stateless in conjunction with PANA using a link-layer or network-layer
   cryptographic mechanism (e.g., IPsec).

11.1.  General Security Measures

   PANA provides multiple mechanisms the first round of message exchange.  However, it
   is difficult to secure a PANA session.

   PANA messages carry sequence numbers, which are monotonically
   incremented by 1 with every new request message.  These numbers prevent all spoofing attacks in the handshake phase
   entirely.

   In networks where lower-layers are
   randomly initialized at not secured prior to running PANA,
   the beginning capability discovery enabled through inclusion of the session, Protection-
   Capability and verified
   against expected numbers upon receipt.  A Post-PANA-Address-Configuration AVPs in a PANA-Start-
   Request message whose sequence
   number is different than the expected one is silently discarded.  In
   addition susceptible to accomplishing orderly delivery spoofing leading to denial-of
   service attacks.  Therefore, usage of these AVPs during the handshake
   phase in such insecure networks is NOT RECOMMENDED.  The same AVPs
   are delivered via an integrity-protected PANA-Bind-Request upon
   successful authentication.

11.3.  EAP Methods

   Eavesdropping EAP messages might cause problems when the EAP method
   is weak and
   duplicate elimination, this scheme also helps prevent enables dictionary or replay attacks or even allows an
   adversary
   spoof messages to disturb ongoing PANA and learn the long-term password directly.  Furthermore, if
   the optional EAP sessions unless Response/Identity payload is used then it can
   also eavesdrop allows the
   adversary to synchronize on learn the expected sequence number.
   Furthermore, impact identity of replay attacks is reduced as any stale message
   (i.e., the PaC.  In such a request or answer with an unexpected sequence number) and
   any duplicate answer are immediately discarded, and case a duplicate
   request can trigger transmission of the cached answer (i.e., no need
   to process privacy
   problem is prevalent.

   To prevent these threats, [I-D.ietf-pana-framework] suggests using
   proper EAP methods for particular environments.  Depending on the request and generate a new answer).

   The PANA framework defines EP
   deployment environment an EAP authentication method which supports
   user identity confidentiality, protection against dictionary attacks
   and session key establishment must be used.  It is ideally located on a network
   device that can filter traffic from therefore the PaCs before
   responsibility of the traffic
   enters network operators and users to choose a proper
   EAP method.

11.4.  Cryptographic Keys

   When the Internet/intranet.  A set of filters can be EAP method exports an MSK, this key is used to
   discard unauthorized packets, such as produce a
   PANA SA with PANA_AUTH_KEY with a PANA-Start-Request message
   that distinct key ID.  The PANA_AUTH_KEY
   is received from the segment of the access network where only unique to the PaCs are supposed PANA session, and takes PANA-based nonce values into
   computation to be connected. cryptographically separate itself from the MSK.

   The protocol also provides PANA_AUTH_KEY is solely used for authentication and integrity
   protection to of the PANA messages when within the used EAP method can generate cryptographic
   session keys.  A designated session.

   The PANA SA lifetime is generated based on the AAA-Key exported bounded by the MSK lifetime.  Another
   execution of EAP method.  This SA is used for generating an AUTH AVP to
   protect the PANA header and payload (including the complete EAP
   message).

   The cryptographic protection prevents an adversary from acting as method yields in a
   man-in-the-middle, injecting messages, replaying messages new MSK, and
   modifying the content of the exchanged messages.  Any packet that
   fails to pass updates the AUTH verification PANA SA,
   PANA_AUTH_KEY and key ID.

   When link-layer or network-layer ciphering [I-D.ietf-pana-ipsec] is silently discarded.  The
   earliest this protection can be
   enabled is when the very first PANA-
   Bind-Request or PANA-FirstAuth-End-Request message that signals as a result of successful authentication is generated.  Starting with these
   messages, any subsequent PANA message until authentication, a PaC-EP-
   Master-Key is generated for each EP from the MSK, session gets torn
   down can be cryptographically protected.

   The PANA SA enables authenticated identifier,
   key identifier, and integrity protected exchange of the EP device ID information between the PaC and PAA.  This identifier.  The PaC-EP-Master-Key
   derivation algorithm defined in Section 5.6 ensures
   there were no man-in-the-middle during the PANA authentication. cryptographic
   independence among different PaC-EP-Master-Keys.

   The lifetime of the PANA SA is set to PANA session lifetime which a PaC-EP-Master-Key is bounded by the authorization lifetime granted by the authentication
   server.  An implementation MAY add lifetime of the
   PANA SA.  This key may be used with a tolerance period secure association protocol
   [RFC4306] to produce further cipher-specific and transient keys.

11.5.  Per-packet Ciphering

   Networks that value.
   Unless are not secured at the lower-layers prior to running
   PANA session is extended by executing another EAP
   authentication, the can rely on enabling per-packet data traffic ciphering upon
   successful PANA SA is removed when the current session
   expires. establishment.  The ability to use cryptographic protection within PANA is determined
   by the used EAP method, which is generally dictated by the deployment
   environment.  Insecure lower-layers necessitate use framework allows
   generation of key-generating
   EAP methods.  In networks where lower-layers are already secured,
   cryptographic a PaC-EP-Master-Key from an MSK for using with a per-
   packet protection of PANA messages is not necessary.

11.2.  Discovery

   The discovery and handshake phase is vulnerable to spoofing attacks mechanism, such as these messages are not authenticated and integrity protected. link-layer or IPsec-based
   ciphering [I-D.ietf-pana-ipsec].  In
   order case the master key is not
   readily useful to prevent very basic denial-of service attacks the ciphering mechanism, an adversary
   should not additional secure
   association protocol [RFC4306] may be able to cause state creation by sending discovery
   messages needed to produce the PAA.  This protection is achieved required
   keying material.  These mechanisms ultimately establish a
   cryptographic binding between the data traffic generated by using and for a cookie-
   based scheme (similar to [RFC2522] which allows
   client and the responder (PAA)
   to be stateless in authenticated identity of the first round client.  Data traffic
   must be minimally data origin authenticated, replay and integrity
   protected, and optionally encrypted.

11.6.  PAA-to-EP Communication

   The PANA framework allows separation of message exchange.  However, it
   is difficult to prevent all spoofing attacks in PAA from EP.  SNMPv3
   [I-D.ietf-pana-snmp] MAY be used between the discovery PAA and
   handshake phase entirely.

   In networks where lower-layers are not secured prior to running PANA, EP for
   provisioning authorized PaC information on the capability discovery enabled through inclusion of Protection-
   Capability EP.  This exchange
   MUST be always physically or cryptographically protected for
   authentication, integrity and Post-PANA-Address-Configuration AVPs in replay protection.  It MUST also be
   privacy-protected when a PANA-Start-
   Request message PaC-EP-Master-Key for per-packet ciphering
   is susceptible transmitted to spoofing leading the EP.

   The PaC-EP-Master-Key MUST be unique to denial-of
   service attacks.  Therefore, usage of these AVPs during the discovery PaC and handshake phase in such insecure networks is NOT RECOMMENDED. EP pair.  The same AVPs are delivered via an integrity-protected PANA-Bind-
   Request upon successful authentication.

11.3.  EAP Methods

   Eavesdropping EAP messages might cause problems when the EAP method
   is weak
   session identifier and enables dictionary or replay attacks or even allows an
   adversary to learn the long-term password directly.  Furthermore, if the optional EAP Response/Identity payload is used then it allows device identifier of the
   adversary EP are taken into
   computation for achieving this effect [I-D.ietf-pana-ipsec].
   Compromise of an EP does not automatically lead to learn the identity compromise of
   another EP or the PaC.  In such a case a privacy
   problem PAA.

11.7.  Liveness Test

   A PANA session is prevalent.

   To prevent these threats, [I-D.ietf-pana-framework] suggests using
   proper EAP methods for particular environments.  Depending on the
   deployment environment an EAP authentication method which supports
   user identity confidentiality, protection against dictionary attacks
   and associated with a session lifetime.  The session key establishment must be used.  It is therefore the
   responsibility
   terminated unless it is refreshed by a new round of EAP
   authentication before it expires.  Therefore, at the network operators and users to choose latest a proper
   EAP method.

11.4.  Separate NAP and ISP Authentication

   The
   disconnected client can be detected when its session expires.  A
   disconnect may also be detected earlier by using PANA design allows running two separate EAP sessions for the same ping messages.
   A request message can be generated by either PaC in the authentication or PAA at any time
   and authorization phase: one with the NAP,
   and one peer must respond with the ISP.  The process an answer message.  A successful
   round-trip of arriving at the resultant
   authorization, which this exchange is a combination of simple verification that the individual
   authorizations obtained from respective service providers, peer is outside
   alive.

   This test can be engaged when there is a possibility that the scope peer
   might have disconnected (e.g., after the discontinuation of data
   traffic for an extended period of time).  Periodic use of this protocol.  In
   exchange as a keep-alive requires additional care as it might result
   in congestion and hence false alarms.

   This exchange is cryptographically protected when a PANA SA is
   available in order to prevent threats associated with the absence abuse of lower-layer security,
   both authentications MUST be able
   this functionality.

   Any valid PANA answer message received in response to generate a AAA-Key, leading recently sent
   request message can be taken as an indication of peer's liveness.
   The PaC or PAA MAY forgo sending an explicit PANA-Ping-Request if a
   recent exchange has already confirmed that the peer is alive.

11.8.  Updating PaC's IP Address

   There is no way to
   generation prove the ownership of a PANA SA.  The resultant PANA SA cryptographically
   binds the two AAA-Keys together, hence it prevents man-in-the-middle
   attacks.

11.5.  Cryptographic Keys

   When IP address presented by
   the EAP method exports PaC.  Hence an authorized PaC can launch a AAA-Key, this key is used to produce redirect attack by
   spoofing a
   PANA SA with PANA_AUTH_KEY with victim's IP address.

11.9.  Early Termination of a distinct key ID. Session

   The PANA_AUTH_KEY
   is unique to the PANA session, and takes PANA-based nonce values into
   computation to cryptographically separate itself from protocol supports the AAA-Key.

   The PANA_AUTH_KEY is solely used ability for authentication both the PaC and integrity
   protection of the PANA messages within PAA
   to transmit a tear-down message before the designated session.

   Two AAA-Keys may be generated as session lifetime expires.
   This message causes state removal, a result stop of separate NAP the accounting procedure
   and ISP
   authentication.  In that case, removes the AAA-Key used with installed per-PaC state on the PANA SA EP(s).  This message
   is
   the combination of both keys.

   The cryptographically protected when PANA SA lifetime is bounded by the AAA-Key lifetime.  Another
   execution of EAP method yields in a new AAA-Key, present.

12.  Acknowledgments

   We would like to thank Jari Arkko, Mohan Parthasarathy, Julien
   Bournelle, Rafael Marin Lopez, Pasi Eronen, Randy Turner, Erik
   Nordmark, Lionel Morand, Avi Lior, Susan Thomson, Giaretta Gerardo,
   Joseph Salowey, Sasikanth Bharadwaj, Spencer Dawkins, Tom Yu, Bernard
   Aboba and updates all members of the PANA
   SA, PANA_AUTH_KEY working group for their valuable
   comments to this document.

13.  References

13.1.  Normative References

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              February 1997.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC2234]  Crocker, D., Ed. and key ID.

   When link-layer or network-layer ciphering [I-D.ietf-pana-ipsec] is
   enabled as P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, November 1997.

   [RFC2279]  Yergeau, F., "UTF-8, a result transformation format of successful PANA authentication, a PaC-EP-
   Master-Key is generated for each EP from the AAA-Key, session
   identifier, key identifier, ISO
              10646", RFC 2279, January 1998.

   [RFC2462]  Thomson, S. and the EP device identifier.  The PaC-
   EP-Master-Key derivation algorithm defined in Section 5.6 ensures
   cryptographic independency among different PaC-EP-Master-Keys.

   The lifetime T. Narten, "IPv6 Stateless Address
              Autoconfiguration", RFC 2462, December 1998.

   [RFC2464]  Crawford, M., "Transmission of PaC-EP master key is bounded by the lifetime IPv6 Packets over Ethernet
              Networks", RFC 2464, December 1998.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3456]  Patel, B., Aboba, B., Kelly, S., and V. Gupta, "Dynamic
              Host Configuration Protocol (DHCPv4) Configuration of the
   PANA SA.  This key may be used with a secure association protocol
   [RFC4306] to produce further cipher-specific
              IPsec Tunnel Mode", RFC 3456, January 2003.

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and transient keys.

11.6.  Per-packet Ciphering

   Networks that are not secured at the lower-layers prior to running
   PANA can rely on enabling per-packet data traffic ciphering upon
   successful PANA session establishment.  The J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, "Extensible Authentication Protocol (EAP)",
              RFC 3748, June 2004.

   [RFC4086]  Eastlake, D., Schiller, J., and S. Crocker, "Randomness
              Requirements for Security", BCP 106, RFC 4086, June 2005.

   [I-D.ietf-ltru-registry]
              Phillips, A. and M. Davis, "Tags for Identifying
              Languages", draft-ietf-ltru-registry-14 (work in
              progress), October 2005.

   [I-D.ietf-dhc-paa-option]
              Kumar, S., "DHCP options for PANA framework allows
   generation of a PaC-EP master key from AAA-Key Authentication Agents",
              draft-ietf-dhc-paa-option-03 (work in progress),
              July 2006.

   [IANA]     Narten, T. and H. Alvestrand, "Guidelines for using with a per-
   packet protection mechanism, such as link-layer or IPsec-based
   ciphering [I-D.ietf-pana-ipsec].  In case the master key is not
   readily useful to the ciphering mechanism, Writing an additional secure
   association protocol [RFC4306] may be needed to produce the required
   keying material.  These mechanisms ultimately establish a
   cryptographic binding between the data traffic generated by
              IANA Considerations Section in RFCs",  BCP 26, RFC 2434,
              October 1998.

13.2.  Informative References

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for a
   client Private Internets",
              BCP 5, RFC 1918, February 1996.

   [RFC2522]  Karn, P. and the authenticated identity of the client.  Data traffic
   must be minimally data origin authenticated, replay W. Simpson, "Photuris: Session-Key Management
              Protocol", RFC 2522, March 1999.

   [RFC2409]  Harkins, D. and D. Carrel, "The Internet Key Exchange
              (IKE)", RFC 2409, November 1998.

   [RFC2461]  Narten, T., Nordmark, E., and integrity
   protected, W. Simpson, "Neighbor
              Discovery for IP Version 6 (IPv6)", RFC 2461,
              December 1998.

   [RFC3927]  Cheshire, S., Aboba, B., and optionally encrypted.

11.7.  PAA-to-EP Communication

   The PANA framework allows separation E. Guttman, "Dynamic
              Configuration of PAA from EP(s).  SNMPv3
   [I-D.ietf-pana-snmp] is used between the PAA IPv4 Link-Local Addresses", RFC 3927,
              May 2005.

   [RFC4016]  Parthasarathy, M., "Protocol for Carrying Authentication
              and EP Network Access (PANA) Threat Analysis and Security
              Requirements", RFC 4016, March 2005.

   [RFC4058]  Yegin, A., Ohba, Y., Penno, R., Tsirtsis, G., and C. Wang,
              "Protocol for provisioning
   authorized PaC information on the EP.  This exchange MUST be always
   physically or cryptographically protected Carrying Authentication for authentication,
   integrity Network Access
              (PANA) Requirements", RFC 4058, May 2005.

   [RFC4137]  Vollbrecht, J., Eronen, P., Petroni, N., and replay protection.  It MUST also be privacy-protected
   when PaC-EP master key Y. Ohba,
              "State Machines for per-packet ciphering is transmitted to the
   EP.

   The PaC-EP master key MUST be unique to the PaC Extensible Authentication Protocol
              (EAP) Peer and EP pair.  The
   session identifier Authenticator", RFC 4137, August 2005.

   [RFC4284]  Adrangi, F., Lortz, V., Bari, F., and P. Eronen, "Identity
              Selection Hints for the device identifier of Extensible Authentication Protocol
              (EAP)", RFC 4284, January 2006.

   [RFC4306]  Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
              RFC 4306, December 2005.

   [RFC4307]  Schiller, J., "Cryptographic Algorithms for Use in the EP are taken into
   computation
              Internet Key Exchange Version 2 (IKEv2)", RFC 4307,
              December 2005.

   [I-D.ietf-eap-keying]
              Aboba, B., "Extensible Authentication Protocol (EAP) Key
              Management Framework", draft-ietf-eap-keying-14 (work in
              progress), June 2006.

   [I-D.ietf-pana-ipsec]
              Parthasarathy, M., "PANA Enabling IPsec based Access
              Control", draft-ietf-pana-ipsec-07 (work in progress),
              July 2005.

   [I-D.ietf-pana-framework]
              Jayaraman, P., "PANA Framework",
              draft-ietf-pana-framework-06 (work in progress),
              March 2006.

   [I-D.ietf-pana-snmp]
              Mghazli, Y., "SNMP usage for achieving this effect [I-D.ietf-pana-ipsec].
   Compromise of PAA-EP interface",
              draft-ietf-pana-snmp-06 (work in progress), June 2006.

   [I-D.ietf-mobike-protocol]
              Eronen, P., "IKEv2 Mobility and Multihoming Protocol
              (MOBIKE)", draft-ietf-mobike-protocol-08 (work in
              progress), February 2006.

   [ianaweb]  IANA, "Number assignment",  http://www.iana.org.

   [IANA-EXP]
              Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful",  BCP 82, RFC 3692, January 2004.

Appendix A.  IP Address Configuration

   The PaC configures an EP does not automatically lead to compromise of
   another EP or IP address before the PAA.

11.8.  Liveness Test

   A PANA session exchange begins.
   This address is associated with called a pre-PANA address (PRPA).  After a successful
   authentication, the client may have to configure a session lifetime.  The session new IP address for
   communication with other nodes, if the PRPA is
   terminated unless it a local-use (e.g., a
   link-local or private address) or a temporarily allocated IP address.
   This IP address is refreshed by called a new round post-PANA address (POPA).  An operator
   might choose allocating a POPA only after successful PANA
   authorization either to prevent waste of EAP
   authentication before it expires.  Therefore, at premium (e.g., globally
   routable) IP resources until the latest a
   disconnected client is authorized, or to enable
   client identity based address assignment.

   There are different methods by which a PRPA can be detected when its session expires.  A
   disconnect configured.

   1. In some deployments (e.g., DSL networks) the PaC may also be detected earlier by using PANA ping messages.
   A request message statically
      configured with an IP address.  This address can be generated by either PaC or PAA at any time
   and the peer must respond with used as a
      PRPA.

   2. In IPv4, some clients attempt to configure an answer message.  A successful
   round-trip of this exchange is address dynamically
      using DHCP [RFC2131].  If they are unable to configure an address
      using DHCP, they can configure a simple verification that link-local address using
      [RFC3927].

      When the peer network access provider is
   alive. able to run a DHCP server on
      the access link, the client would configure the PRPA using DHCP.
      This test address may be from a private address pool [RFC1918].  Also,
      the lease time on the address may vary.  For example, a PRPA
      configured solely for running PANA can have a short lease time.
      The PRPA may be engaged when used for local-use only (i.e., only for on-link
      communication, such as for PANA and IPsec tunneling with EP), or
      also for ultimate end-to-end data communication.

      In case there is a possibility that no running DHCP server on the peer
   might have disconnected (e.g., after link, the discontinuation of data
   traffic client
      might fall back to configuring a PRPA via zeroconfiguration
      technique [RFC3927].  This yields a long-term address that can
      only be used for an extended period of time).  Periodic use on-link communication.  (Note: At time of this
   exchange as
      writing, the zeroconfiguration technique is not widely implemented
      in routers.)

   3. In IPv6, clients automatically configure a keep-alive requires additional care link-local address
      [RFC2462] when they initialize an interface.  Additionally, they
      may also configure non-link-local address(es) when DHCP or router
      advertisements with prefixes are made available to the them.

   In case PAA is not on the same IP subnet as it might result
   in congestion and hence false alarms.

   This exchange the PaCs are, the
   deployment needs to ensure that a non-link-local PRPA is cryptographically protected when configurable
   by the clients.

   When a PANA SA PRPA is
   available in order to prevent threats associated with configured, the client starts the abuse of
   this functionality.

   Any valid PANA answer message received in response to exchange.  By
   that time, a recently sent
   request message can be taken as dual stacked client might have configured both an indication IPv4
   address and an IPv6 address as PRPAs.  Regardless of peer's liveness.
   The whether the PaC
   has both IPv4 and IPv6 PRPAs or PAA MAY forgo sending an explicit PANA-Ping-Request if only one of those, only one PANA run
   is required.  When a
   recent exchange has already confirmed that dual-stack PaC or PAA initiates PANA
   authentication, it chooses either IPv4 or IPv6 where the peer is alive.

11.9.  Updating PaC's IP Address

   There choice is no way
   made depending on the deployment.

   When the client successfully authenticates to prove the ownership of network, it may be
   required to configure POPAs for its subsequent data communication
   with the IP address presented by other nodes.

   If the PaC.  Hence client is already configured with an authorized PaC address that can launch a redirect attack by
   spoofing a victim's IP address.

11.10.  Early Termination of be used
   with data communication, it is not required to configure a Session

   The PANA protocol supports the ability for both POPA.
   Otherwise, the PaC and PANA-Bind-Request message allows the PAA to transmit a tear-down message before indicate
   the session lifetime expires.
   This message causes state removal, a stop available configuration methods to the PaC.  The PaC can choose
   one of the accounting procedure methods and removes act accordingly.

   1. If the installed per-PaC state network relies on physical or link layer security, the EP(s).  This message
   is cryptographically protected PaC
      can configure a POPA using DHCP [RFC2131] [RFC3315] or using IPv6
      stateless auto-configuration [RFC2461].  An IPv4 PRPA SHOULD be
      unconfigured when PANA SA is present.

12.  Acknowledgments

   We would like to thank Jari Arkko, Mohan Parthasarathy, Julien
   Bournelle, Rafael Marin Lopez, Pasi Eronen, Randy Turner, Erik
   Nordmark, Lionel Morand, Avi Lior, Susan Thomson, Giaretta Gerardo,
   Joseph Salowey, Sasikanth Bharadwaj and all members of the PANA
   working group for their valuable comments to this document.

13.  References

13.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs POPA is configured to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC2234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, November 1997.

   [RFC2279]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", RFC 2279, January 1998.

   [RFC2365]  Meyer, D., "Administratively Scoped IP Multicast", BCP 23,
              RFC 2365, July 1998.

   [RFC2462]  Thomson, S. and T. Narten, "IPv6 Stateless Address
              Autoconfiguration", RFC 2462, December 1998.

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, December 1998.

   [RFC2988]  Paxson, V. and M. Allman, "Computing TCP's Retransmission
              Timer", RFC 2988, November 2000.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., prevent IPv4 address
      selection problem [RFC3927].

      If the PaC is a dual-stacked node, it can configure both IPv4 and M. Carney, "Dynamic Host Configuration Protocol for
      IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3456]  Patel, B., Aboba, B., Kelly, S., and V. Gupta, "Dynamic
              Host Configuration Protocol (DHCPv4) Configuration of type POPAs.  The available POPA configuration methods are
      indicated within PANA.

   2. If the network uses IPsec Tunnel Mode", RFC 3456, January 2003.

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, "Extensible Authentication Protocol (EAP)",
              RFC 3748, June 2004.

   [RFC4086]  Eastlake, D., Schiller, J., and S. Crocker, "Randomness
              Requirements for Security", BCP 106, RFC 4086, June 2005.

   [I-D.ietf-ltru-registry]
              Phillips, A. and M. Davis, "Tags for Identifying
              Languages", draft-ietf-ltru-registry-14 (work in
              progress), October 2005.

   [IANA]     Narten, T. and H. Alvestrand, "Guidelines for Writing protecting the traffic on the link
      subsequent to PANA authentication [I-D.ietf-pana-ipsec], the PaC
      would use the PRPA as the outer address of IPsec tunnel mode SA
      (IPsec-TOA).  The PaC also needs to configure an
              IANA Considerations Section inner address
      (IPsec-TIA).  There are different ways to configure an IPsec-TIA
      which are indicated in RFCs",  BCP 26, RFC 2434,
              October 1998.

13.2.  Informative References

   [RFC2522]  Karn, P. and W. Simpson, "Photuris: Session-Key Management
              Protocol", RFC 2522, March 1999.

   [RFC4016]  Parthasarathy, M., "Protocol for Carrying Authentication
              and Network Access (PANA) Threat Analysis and Security
              Requirements", RFC 4016, March 2005.

   [RFC4058]  Yegin, A., Ohba, Y., Penno, R., Tsirtsis, G., a PANA-Bind-Request message.

      When an IPv4 PRPA is configured, the same address may be used as
      both IPsec-TOA and C. Wang,
              "Protocol IPsec-TIA.  In this case, a POPA is not
      configured.  Alternatively, an IPsec-TIA can be obtained via the
      configuration method available within [RFC3456] for Carrying Authentication IPv4,
      [RFC4307] for Network Access
              (PANA) Requirements", RFC 4058, May 2005.

   [RFC4137]  Vollbrecht, J., Eronen, P., Petroni, N., both IPv4 and Y. Ohba,
              "State Machines IPv6.  This newly configured address
      constitutes a POPA.  Please refer to [I-D.ietf-pana-ipsec] for Extensible Authentication Protocol
              (EAP) Peer and Authenticator", RFC 4137, August 2005.

   [RFC4284]  Adrangi, F., Lortz, V., Bari, F.,
      more details.

      IKEv2 [RFC4307] can enable configuration of one IPv4 IPsec-TIA and P. Eronen, "Identity
              Selection Hints
      one IPv6 IPsec-TIA for the Extensible Authentication Protocol
              (EAP)", RFC 4284, January 2006.

   [RFC4306]  Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
              RFC 4306, December 2005.

   [I-D.ietf-eap-keying]
              Aboba, B., "Extensible Authentication Protocol (EAP) Key
              Management Framework", draft-ietf-eap-keying-09 (work in
              progress), January 2006.

   [I-D.ietf-pana-ipsec]
              Parthasarathy, M., "PANA Enabling same IPsec based Access
              Control", draft-ietf-pana-ipsec-07 (work in progress),
              July 2005.

   [I-D.ietf-pana-framework]
              Jayaraman, P., "PANA Framework",
              draft-ietf-pana-framework-05 (work in progress),
              July 2005.

   [I-D.ietf-pana-snmp]
              Mghazli, Y., "SNMP usage for PAA-EP interface",
              draft-ietf-pana-snmp-05 (work in progress), January 2006.

   [I-D.ietf-mobike-protocol]
              Eronen, P., "IKEv2 Mobility and Multihoming Protocol
              (MOBIKE)", draft-ietf-mobike-protocol-08 (work in
              progress), February 2006.

   [I-D.ietf-dna-link-information]
              Yegin, A., "Link-layer Event Notifications tunnel mode SA.  Therefore,
      IKEv2 is recommended for Detecting
              Network Attachments", draft-ietf-dna-link-information-03
              (work in progress), October 2005.

   [ianaweb]  IANA, "Number assignment",  http://www.iana.org.

   [IANA-EXP]
              Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful",  BCP 82, RFC 3692, January 2004.

Appendix A.  Example Sequence handling dual-stacked PaCs where single
      execution of Separate NAP and ISP Authentication

   A PANA message sequence with separate NAP and ISP authentication IKE is
   illustrated in Figure 12.  The example assumes the following
   scenario:

   o  The PaC initiates desired.  In this case, the discovery and handshake phase.

   o  The PAA offers separate NAP same IP
      version that has been used for PANA is used for IKE, and ISP authentication, as well as a
      choice the IKE
      entity on the dual-stack PaC will request one or both of ISP from "ISP1" IPv4 and "ISP2".  The PaC accepts the offer
      IPv6 IPsec-TIAs from PAA, with choosing "ISP1" as the ISP.

   o  NAP authentication and ISP authentication is performed in this
      order in IKE entity on the authentication EP and authorization phase.

   o  An EAP authentication method with obtain the
      one(s) that is/are available on the EP.

   Although there are potentially a single round trip is used in
      each EAP sequence.

   o  After number of different ways to
   configure a PANA SA is established, all messages are integrity PRPA, and
      replay protected with AUTH AVPs.

   o POPA when necessary, it should be noted that
   the ultimate decision to use one or more of these in a deployment
   depends on the operator.  The access, re-authentication decision is dictated by the operator's
   choice of per-packet protection capability (physical and termination phases are not
      shown.

   PaC      PAA  Message(sequence number)[AVPs]
   -----------------------------------------------------
   // Discovery link-layer
   vs network-layer), PRPA type (local and handshake phase
      ----->     PANA-PAA-Discover(0)
      <-----     PANA-Start-Request(x)     // S-flag set.
                    [Cookie,
                     ISP-Information("ISP1"),
                     ISP-Information("ISP2"),
                     NAP-Information("MyNAP")]
      ----->     PANA-Start-Answer(x)      // S-flag set.
                    [Cookie,               // PaC chooses "ISP1".
                     ISP-Information("ISP1")]

   // Authentication temporary vs global and authorization phase
      <-----     PANA-Auth-Request(x+1)    // NAP authentication.
                    [Session-Id, Nonce,    // (S,N)-flags set
                     EAP{Request}]         // for all messages during
                                           // NAP authentication.
      ----->     PANA-Auth-Answer(x+1)[Session-Id, Nonce]
      ----->     PANA-Auth-Request(y)[Session-Id, EAP{Response}]
      <-----     PANA-Auth-Answer(y)[Session-Id]
      <-----     PANA-Auth-Request(x+2)[Session-Id, EAP{Request}]
      ----->     PANA-Auth-Answer(x+2)[Session-Id, EAP{Response}]
      <-----     PANA-FirstAuth-End-Request(x+3)
                    [Session-Id, EAP{Success}, Key-Id, Algorithm, AUTH]
      ----->     PANA-FirstAuth-End-Answer(x+3)
                    [Session-Id, Key-Id, AUTH]
      <-----     PANA-Auth-Request(x+4)     // ISP authentication.
                    [Session-Id, EAP{Request}, AUTH]  // Only S-flag set
                                            // for all messages during
                                            // ISP authentication.
      ----->     PANA-Auth-Answer(x+4)[Session-Id, AUTH]
      ----->     PANA-Auth-Request(y+1)[Session-Id, EAP{Response}, AUTH]
      <-----     PANA-Auth-Answer(y+1)[Session-Id, AUTH]
      <-----     PANA-Auth-Request(x+5)[Session-Id, EAP{Request}, AUTH]
      ----->     PANA-Auth-Answer(x+5)[Session-Id, EAP{Response}, AUTH]
      <-----     PANA-Bind-Request(x+6)
                    [Session-Id, Result-Code, EAP{Success}, Device-Id,
                     Key-Id, Lifetime, Protection-Cap., PPAC, AUTH]
      ----->     PANA-Bind-Answer(x+6)[Session-Id, Device-Id, Key-Id,
                     PPAC, AUTH]

   Figure 12: A Complete Message Sequence for Separate NAP long-
   term), and ISP
   Authentication POPA configuration mechanisms available in the network.

Authors' Addresses

   Dan Forsberg
   Nokia Research Center
   P.O. Box 407
   FIN-00045 NOKIA GROUP
   Finland

   Phone: +358 50 4839470
   Email: dan.forsberg@nokia.com

   Yoshihiro Ohba
   Toshiba America Research, Inc.
   1 Telcordia Drive
   Piscataway, NJ  08854
   USA

   Phone: +1 732 699 5305
   Email: yohba@tari.toshiba.com

   Basavaraj Patil
   Nokia
   6000 Connection Dr.
   Irving, TX  75039
   USA

   Phone: +1 972-894-6709
   Email: Basavaraj.Patil@nokia.com

   Hannes Tschofenig
   Siemens Corporate Technology
   Otto-Hahn-Ring 6
   81739 Munich
   Germany

   Email: Hannes.Tschofenig@siemens.com
   Alper E. Yegin
   Samsung Advanced Institute of Technology
   Istanbul,
   Turkey

   Phone: +90 538 719 0181
   Email: alper01.yegin@partner.samsung.com

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