Internet DRAFT - draft-ietf-ipv6-over-ppp-v2

draft-ietf-ipv6-over-ppp-v2





IPv6 Working Group                             S.Varada (Editor) 
Internet-Draft                               Transwitch  
Obsoletes: RFC 2472 (if approved)             D.Haskins  
Category: Standards track                      Ed Allen  
Expires: November 2007                         May 2007  
    
                           IP Version 6 over PPP 
                   <draft-ietf-ipv6-over-ppp-v2-03.txt> 
 
Status of this Memo 
                                                                         
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      any applicable patent or other IPR claims of which he or she is 
      aware have been or will be disclosed, and any of which he or she 
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      BCP 79. 
    
      Internet-Drafts are working documents of the Internet Engineering 
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      The list of Internet-Draft Shadow Directories can be accessed at 
      http://www.ietf.org/shadow.html. 
 
Copyright Notice 
    
      Copyright (C) The IETF Trust (2007).   
    
Abstract 
    
      The Point-to-Point Protocol (PPP) provides a standard method of 
      encapsulating Network Layer protocol information over  
      point-to-point links.  PPP also defines an extensible Link Control  
      Protocol, and proposes a family of Network Control Protocols  
      (NCPs) for establishing and configuring different network-layer  
      protocols. 
    
      This document defines the method for sending IPv6 packets over PPP 
      links, the NCP for establishing and configuring the IPv6 over PPP 
      and the method for forming IPv6 link-local addresses on PPP links. 
 
 
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      It also specifies the conditions for performing Duplicate Address 
      Detection on IPv6 global unicast addresses configured for PPP 
      links either through stateful or stateless address 
      autoconfiguration. 
    
      This document obsoletes RFC 2472. 
    
Table of Contents 
 
   1. Introduction...................................................2 
      1.1 Specification of Requirements..............................3 
   2. Sending IPv6 Datagrams.........................................3 
   3. A PPP Network Control Protocol for IPv6........................3 
   4. IPV6CP Configuration Options...................................4 
      4.1 Interface-Identifier.......................................5 
   5. Stateless Autoconfiguration and Link-Local Addresses..........10 
   6. Security Considerations.......................................11 
   7. IANA Considerations...........................................12 
   8. Acknowledgments...............................................12 
   9. References....................................................12 
      9.1 Normative References......................................12 
      9.2 Informative references....................................13 
   Appendix A:  Global Scope Addresses..............................13 
   Appendix B:  Changes from RFC-2472...............................14 
   Authors' Addresses...............................................14 
   IPR Notice  .....................................................14 
   Copyright Notice and Disclaimer..................................15 
    
    
1. Introduction 
    
      PPP has three main components: 
    
      1) A method for encapsulating datagrams over serial links. 
    
      2) A Link Control Protocol (LCP) for establishing, configuring,  
         and testing the data-link connection. 
    
      3) A family of Network Control Protocols (NCPs) for establishing  
         and configuring different network-layer protocols. 
    
      In order to establish communications over a point-to-point link,  
      each end of the PPP link must first send LCP packets to  
      configure and test the data link.  After the link has been  
      established and optional facilities have been negotiated as  
      needed by the LCP, PPP must send NCP packets to choose and  
      configure one or more network-layer protocols.  Once each of the  
      chosen network-layer protocols has been configured, datagrams  
      from each network-layer protocol can be sent over the link. 
 
 
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      In this document, the NCP for establishing and configuring the 
      IPv6 over PPP is referred as the IPv6 Control Protocol (IPV6CP). 
       
      The link will remain configured for communications until  
      explicit LCP or NCP packets close the link down, or until some  
      external event occurs (power failure at the other end, carrier 
      drop, etc.). 
       
      This document obsoletes the earlier specification from RFC 2472 
      [8]. Changes from RFC 2472 are listed in Appendix B. 
 
1.1 Specification of Requirements 
    
      In this document, several words are used to signify the  
      requirements of the specification. 
    
      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 [7]. 
    
2. Sending IPv6 Datagrams 
    
      Before any IPv6 packets may be communicated, PPP MUST reach the 
      Network-Layer Protocol phase, and the IPv6 Control Protocol MUST 
      reach the Opened state. 
    
      Exactly one IPv6 packet is encapsulated in the Information field  
      of PPP Data Link Layer frames where the Protocol field indicates  
      Type hex 0057 (Internet Protocol Version 6). 
    
      The maximum length of an IPv6 packet transmitted over a PPP link 
      is the same as the maximum length of the Information field of a  
      PPP data link layer frame.  PPP links supporting IPv6 MUST allow  
      the information field at least as large as the minimum link MTU  
      size required for IPv6 [2]. 
    
3. A PPP Network Control Protocol for IPv6 
    
      The IPv6 Control Protocol (IPV6CP) is responsible for  
      configuring, enabling, and disabling the IPv6 protocol modules  
      on both ends of the point-to-point link.  IPV6CP uses the same 
      packet exchange mechanism as the LCP. IPV6CP packets may not be 
      exchanged until PPP has reached the Network-Layer Protocol phase.  
      IPV6CP packets received before this phase is reached should be  
      silently discarded. 
    
    
 
 
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      The IPv6 Control Protocol is exactly the same as the LCP [1] with  
      the following exceptions: 
    
        Data Link Layer Protocol Field 
    
            Exactly one IPV6CP packet is encapsulated in the 
            Information field of PPP Data Link Layer frames where the  
            Protocol field indicates type hex 8057 (IPv6 Control  
            Protocol). 
    
        Code field 
 
            Only Codes 1 through 7 (Configure-Request, Configure-Ack,          
            Configure-Nak, Configure-Reject, Terminate-Request,          
            Terminate-Ack and Code-Reject) are used.  Other Codes  
            should be treated as unrecognized and should result in  
            Code-Rejects. 
    
        Timeouts 
    
             IPV6CP packets may not be exchanged until PPP has reached  
             the Network-Layer Protocol phase.  An implementation 
             should be prepared to wait for Authentication and Link 
             Quality Determination to finish before timing out waiting  
             for a Configure-Ack or other response.  It is suggested  
             that an implementation give up only after user  
             intervention or a configurable amount of time. 
    
        Configuration Option Types 
    
             IPV6CP has a distinct set of Configuration Options. 
 
4. IPV6CP Configuration Options 
    
      IPV6CP Configuration Options allow negotiation of desirable IPv6 
      parameters.  IPV6CP uses the same Configuration Option format  
      defined for LCP [1] but with a separate set of Options.  If a  
      Configuration Option is not included in a Configure-Request  
      packet, the default value for that Configuration Option is  
      assumed. 
    
      Up-to-date values of the IPV6CP Option Type field are specified  
      in the on-line database of "Assigned Numbers" maintained at  
      IANA [4].  Current value is assigned as follows: 
    
         1 Interface-Identifier 
    
      The only IPV6CP option defined in this document is the Interface 
      Identifier.  Any other IPV6CP configuration options that can be 
 
 
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      defined over time are to be defined in separate documents. 
    
4.1 Interface-Identifier 
 
      Description 
    
      This Configuration Option provides a way to negotiate an unique 
      64-bit interface identifier to be used for the address 
      autoconfiguration [3] at the local end of the link (see  
      section 5).  A Configure-Request MUST contain exactly one  
      instance of the Interface-Identifier option [1].  The interface 
      identifier MUST be unique within the PPP link; i.e. upon  
      completion of the negotiation different Interface-Identifier 
      values are to be selected for the ends of the PPP link.  The  
      interface identifier may also be unique over a broader scope. 
    
      Before this Configuration Option is requested, an implementation 
      chooses its tentative Interface-Identifier.  The non-zero value of 
      the tentative Interface-Identifier SHOULD be chosen such that the 
      value is unique to the link and, preferably, consistently 
      reproducible across initializations of the IPV6CP finite state 
      machine (administrative Close and reOpen, reboots, etc).  The 
      rationale for preferring a consistently reproducible unique 
      interface identifier to a completely random interface identifier 
      is to provide stability to global scope addresses (see Appendix A) 
      that can be formed from the interface identifier  
    
      Assuming that interface identifier bits are numbered from 0 to 
      63 in canonical bit order where the most significant bit is 
      the bit number 0, the bit number 6 is the "u" bit (universal/local   
      bit in  IEEE EUI-64 [5] terminology) which indicates whether or  
      not the interface identifier is based on a globally unique IEEE  
      identifier (EUI-48 or EUI-64[5])(see the case 1 below).  It is set  
      to one (1) if a globally unique IEEE identifier is used to derive  
      the interface-identifier, and it is set to zero (0) otherwise. 
    
      The following are methods for choosing the tentative Interface 
      Identifier in the preference order: 
    
        1)If an IEEE global identifier (EUI-48 or EUI-64) is 
          available anywhere on the node, it should be used to  
          construct the tentative Interface-Identifier due to its  
          uniqueness properties.  When extracting an IEEE global  
          identifier from another device on the node, care should be  
          taken that the extracted identifier is presented in  
          canonical ordering [14]. 
    
          The only transformation from an EUI-64 identifier is to invert 
          the "u" bit (universal/local bit in IEEE EUI-64 terminology). 
 
 
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          For example, for a globally unique EUI-64 identifier of the 
          form: 
    
   most-significant                                    least significant 
   bit                                                               bit 
   |0              1|1              3|3              4|4              6| 
   |0              5|6              1|2              7|8              3| 
   +----------------+----------------+----------------+----------------+ 
      
   |cccccc0gcccccccc|cccccccceeeeeeee|eeeeeeeeeeeeeeee|eeeeeeeeeeeeeeee| 
   +----------------+----------------+----------------+----------------+ 
             
            where "c" are the bits of the assigned company_id, "0" is  
           the value of the universal/local bit to indicate global 
           scope, "g" is group/individual bit, and "e" are the bits 
           of the extension identifier, the IPv6 interface identifier 
           would be of the form: 
    
   most-significant                                    least-significant 
   bit                                                               bit 
   |0              1|1              3|3              4|4              6| 
   |0              5|6              1|2              7|8              3| 
   +----------------+----------------+----------------+----------------+ 
      
   |cccccc1gcccccccc|cccccccceeeeeeee|eeeeeeeeeeeeeeee|eeeeeeeeeeeeeeee| 
   +----------------+----------------+----------------+----------------+ 
    
           The only change is inverting the value of the 
           universal/local bit. 
    
           In the case of a EUI-48 identifier, it is first converted  
           to the EUI-64 format by inserting two bytes, with  
           hexa-decimal values of 0xFF and 0xFE, in the middle of the 
           48 bit MAC (between the company_id and extension identifier 
           portions of the EUI-48 value).  For example, for a globally 
           unique 48 bit EUI-48 identifier of the 
           form: 
    
      most-significant                   least-significant 
      bit                                              bit 
      |0              1|1              3|3              4| 
      |0              5|6              1|2              7| 
      +----------------+----------------+----------------+ 
      |cccccc0gcccccccc|cccccccceeeeeeee|eeeeeeeeeeeeeeee| 
      +----------------+----------------+----------------+ 
    
           where "c" are the bits of the assigned company_id, "0" is 
           the value of the universal/local bit to indicate global  
           scope, "g" is group/individual bit, and "e" are the bits 
 
 
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           of the extension identifier, the IPv6 interface identifier 
           would be of the form: 
 
   most-significant                                    least-significant 
   bit                                                               bit 
   |0              1|1              3|3              4|4              6| 
   |0              5|6              1|2              7|8              3| 
   +----------------+----------------+----------------+----------------+ 
      
   |cccccc1gcccccccc|cccccccc11111111|11111110eeeeeeee|eeeeeeeeeeeeeeee| 
   +----------------+----------------+----------------+----------------+ 
    
        2) If an IEEE global identifier is not available, a different 
           source of uniqueness should be used.  Suggested sources of 
           uniqueness include link-layer addresses, machine serial 
           numbers, et cetera.  In this case, the "u" bit of the 
           interface-identifier MUST be set to zero (0). 
    
        3) If a good source of uniqueness cannot be found, it is 
           recommended that a random number be generated.  In this 
           case, the "u" bit of the interface-identifier MUST be set to  
           zero (0). 
    
      Good sources [1] of uniqueness or randomness are required for  
      the Interface-Identifier negotiation to succeed.  If neither an  
      unique number or a random number can be generated, it is  
      recommended that a zero value be used for the Interface 
      Identifier transmitted in the Configure-Request.  In this case  
      the PPP peer may provide a valid non-zero Interface-Identifier 
      in its response as described below. Note that if at least one of  
      the PPP peers is able to generate separate non-zero numbers for  
      itself and its peer, the identifier negotiation will succeed. 
    
      When a Configure-Request is received with the Interface 
      Identifier Configuration Option and the receiving peer  
      implements this option, the received Interface-Identifier is  
      compared with the Interface-Identifier of the last  
      Configure-Request sent to the peer. Depending on the result of the  
      comparison an implementation MUST respond in one of the  
      following ways: 
    
      If the two Interface-Identifiers are different but the received 
      Interface-Identifier is zero, a Configure-Nak is sent with a 
      non-zero Interface-Identifier value suggested for use by the  
      remote peer.  Such a suggested Interface-Identifier MUST be 
      different from the Interface-Identifier of the last  
      Configure-Request sent to the peer.  It is recommended that the 
      value suggested be consistently reproducible across 
      initializations of the IPV6CP finite state machine (administrative 
 
 
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      Close and reOpen, reboots, etc). The "u" (universal/local) bit of 
      the suggested identifier MUST be set to zero (0) regardless of its  
      source unless the globally unique EUI-48/EUI-64 derived  
      identifier is provided for the exclusive use by the remote peer. 
    
      If the two Interface-Identifiers are different and the received 
      Interface-Identifier is not zero, the Interface-Identifier MUST be 
      acknowledged, i.e.  a Configure-Ack is sent with the requested 
      Interface-Identifier, meaning that the responding peer agrees with 
      the Interface-Identifier requested. 
    
      If the two Interface-Identifiers are equal and are not zero, 
      Configure-Nak MUST be sent specifying a different non-zero 
      Interface-Identifier value suggested for use by the remote peer. 
      It is recommended that the value suggested be consistently 
      reproducible across initializations of the IPV6CP finite state 
      machine (administrative Close and reOpen, reboots, etc).  The "u" 
      (universal/local) bit of the suggested identifier MUST be set to 
      zero (0) regardless of its source unless the globally unique  
      EUI-48/EUI-64 derived identifier is provided for the exclusive use 
      by the remote peer. 
    
      If the two Interface-Identifiers are equal to zero, the Interface 
      Identifiers negotiation MUST be terminated by transmitting the 
      Configure-Reject with the Interface-Identifier value set to zero. 
      In this case a unique Interface-Identifier can not be negotiated. 
    
      If a Configure-Request is received with the Interface-Identifier 
      Configuration Option and the receiving peer does not implement 
      this option, Configure-Rej is sent. 
    
      A new Configure-Request SHOULD NOT be sent to the peer until 
      normal processing would cause it to be sent (that is, until a 
      Configure-Nak is received or the Restart timer runs out [1]). 
    
      A new Configure-Request MUST NOT contain the Interface-Identifier 
      option if a valid Interface-Identifier Configure-Reject is 
      received. 
    
      Reception of a Configure-Nak with a suggested Interface-Identifier 
      different from that of the last Configure-Nak sent to the peer 
      indicates an unique Interface-Identifier.  In this case a new 
      Configure-Request MUST be sent with the identifier value suggested 
      in the last Configure-Nak from the peer.  But if the received 
      Interface-Identifier is equal to the one sent in the last 
      Configure-Nak, a new Interface-Identifier MUST be chosen.  In this 
      case, a new Configure-Request SHOULD be sent with the new 
      tentative Interface-Identifier.  This sequence (transmit 
      Configure-Request, receive Configure-Request, transmit  
 
 
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      Configure-Nak, receive Configure-Nak) might occur a few times, but 
      it is extremely unlikely to occur repeatedly.  More likely, the 
      Interface-Identifiers chosen at either end will quickly diverge, 
      terminating the sequence. 
    
      If negotiation of the Interface-Identifier is required, and the 
      peer did not provide the option in its Configure-Request, the 
      option SHOULD be appended to a Configure-Nak.  The tentative value 
      of the Interface-Identifier given must be acceptable as the remote 
      Interface-Identifier; i.e.  it should be different from the 
      identifier value selected for the local end of the PPP link.  The 
      next Configure-Request from the peer may include this option.  If 
      the next Configure-Request does not include this option the peer 
      MUST NOT send another Configure-Nak with this option included.  It 
      should assume that the peer's implementation does not support this 
      option. 
    
      By default, an implementation SHOULD attempt to negotiate the 
      Interface-Identifier for its end of the PPP connection. 
 
      A summary of the Interface-Identifier Configuration Option format 
      is shown below.  The fields are transmitted from left to right. 
    
    
      0                   1                   2                   3 
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     Type      |    Length     | Interface-Identifier (MS Bytes) 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                           Interface-Identifier (cont) 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      Interface-Identifier (LS Bytes) | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 
        Type 
    
          1 
    
        Length 
    
          10 
        Interface-Identifier 
    
          The 64-bit Interface-Identifier, which is very likely to be  
          unique on the link, or zero if a good source of uniqueness  
          can not be found. 
 
 

 
 
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        Default 
    
          If no valid interface identifier can be successfully 
          negotiated, no default Interface-Identifier value should be 
          assumed. The procedures for recovering from such a case are 
          unspecified.  One approach is to manually configure the 
          interface identifier of the interface. 
           
5. Stateless Autoconfiguration and Link-Local Addresses  
    
      The Interface-Identifier of IPv6 unicast addresses [6] of a PPP 
      interface, SHOULD be negotiated in the IPV6CP phase of the PPP 
      connection setup (see section 4.1).  If no valid Interface 
      Identifier has been successfully negotiated, procedures for 
      recovering from such a case are unspecified.  One approach is to 
      manually configure the Interface-Identifier of the interface. 
    
      The negotiated Interface-Identifier is used by the local end of 
      the PPP link to autoconfigure IPv6 link-local unicast address for 
      the PPP interface.  However, it SHOULD NOT be assumed that the 
      same Interface-Identifier is used in configuring global unicast 
      addresses for the PPP interface using IPv6 stateless address 
      autoconfiguration [3].  The PPP peer MAY generate one or more 
      Interface Identifiers, for instance, using a method described in 
      [9], to autoconfigure one or more global unicast addresses. 
       
      As long as the Interface-Identifier is negotiated in the IPV6CP 
      phase of the PPP connection setup, it is redundant to perform 
      duplicate address detection (DAD) as a part of the IPv6 Stateless 
      Address Autoconfiguration protocol [3] on the IPv6 link-local 
      address generated by the PPP peer.  It may also be redundant to 
      perform DAD on any global unicast addresses configured (using an 
      Interface-Identifier that is either negotiated during IPV6CP or 
      generated, for instance, as per [9]) for the interface as part of 
      the IPv6 Stateless Address Autoconfiguration protocol [3] provided 
      that the following two conditions are met: 
    
     1) The prefixes advertised, through the Router Advertisement  
        messages, by the access router terminating the PPP link are 
        exclusive to the PPP link. 
       
      2) The access router terminating the PPP link does not 
         autoconfigure any IPv6 global unicast addresses from the 
         prefixes that it advertises. 
 
      Therefore, it is RECOMMENDED that for PPP links with the IPV6CP 
      Interface-Identifier option enabled and satisfying the 
      aforementioned two conditions, the default value of the 
      DupAddrDetectTransmits autoconfiguration variable [3] is set to 
 
 
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      zero by the system management. 3GPP2 networks are an example of a 
      technology that uses PPP to enable a host to obtain an IPv6 global 
      unicast address and satisfies the aforementioned two conditions 
      [10]. 3GPP networks are another example [11] & [13]. 
    
      Link-local addresses 
    
      Link-local addresses of PPP interfaces have the following  
      format: 
 
   | 10 bits  |        54 bits         |          64 bits            | 
   +----------+------------------------+-----------------------------+ 
   |1111111010|           0            |    Interface-Identifier     | 
   +----------+------------------------+-----------------------------+ 
       
      The most significant 10 bits of the address is the Link-Local 
      prefix FE80::.  54 zero bits pad out the address between the 
      Link-Local prefix and the Interface-Identifier fields. 
    
6. Security Considerations 
 
      Lack of link security, such as authentication, trigger the 
      security concerns raised in [3] when stateless address auto-
      configuration method is employed for the generation of global 
      unicast IPv6 addresses out of interface identifiers that are 
      either negotiated through the IPV6CP or generated, for instance, 
      using a method described in [9]. Thus, the mechanisms that are 
      appropriate for ensuring PPP link security are addressed below 
      together with the reference to a generic threat model. 
       
      The mechanisms that are appropriate for ensuring PPP link 
      Security are: 1) Access Control Lists that apply filters on 
      traffic received over the link for enforcing admission policy, 2)  
      an Authentication protocol that facilitates negotiations between 
      peers [15] to select an authentication method (e.g., MD5 [16]) 
      for validation of the peer, and 3) an Encryption protocol that 
      facilitates negotiations between peers to select encryption 
      algorithms (or, crypto-suites) to ensure data confidentiality 
      [17]).  
 
      There are certain threats associated with peer interactions on a 
      PPP link even with one or more of the above security measures in 
      place. For instance, using MD5 authentication method [16] exposes 
      one to replay attack, where in which, an attacker could intercept 
      and replay a station's identity and password hash to get access to 
 
 
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      a network. The user of this specification is advised to refer to 
      [15], which presents a generic threat model, for an understanding 
      of the threats posed to the security of a link. The reference 
      [15] also gives framework to specify requirements for the 
      selection of an authentication method for a given application.  
 
7. IANA Considerations  
    
      The editor has no specific recommendations for the IANA on the 
      assignment of a value for the Type field of IPv6 datagram 
      Interface-Identifier option specified in this specification. The 
      current assignment is up-to-date at [4]. However, the reference 
      to the RFC number needs to be updated. 
    
8. Acknowledgments 
    
      This document borrows from the Magic-Number LCP option and as such 
      is partially based on previous work done by the PPP working group. 
       
      The editor is grateful for the input provided by members of the 
      IPv6 community in the spirit of updating the RFC 2472. Thanks, in 
      particular, go to Pete Barany and Karim El-malki for their 
      technical contributions.  Also, thanks to Alex Conta, for a 
      thorough reviewing, Stephen Kent, for helping with security 
      aspects, Spencer Dawkins and Pekka Savola for the nits. Finally, 
      the author is grateful to Jari Arkko, for his initiation to bring 
      closure to this specification.  
       
9. References 
    
9.1 Normative References 
    
   [1]   Simpson, W., "The Point-to-Point Protocol," STD 51, RFC 
         1661, July 1994. 
    
   [2]   Deering, S., and R. Hinden, Editors, "Internet Protocol,  
         Version 6 (IPv6) Specification," RFC 2460, December 1998. 
    
   [3]   Thomson, S., and T. Narten, "IPv6 Stateless Address 
         Autoconfiguration," RFC 2462, December 1998. 
    
   [4]   IANA, "Assigned Numbers," http://www.iana.org/numbers.html 
    
   [5]   IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) 
         Registration Authority", April 2004. 
    
    
 
 
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   [6]   Hinden, R., and S. Deering, "IP Version 6 Addressing 
         Architecture", RFC 4291, February 2006. 
    
   [7]   Bradner, S., "Key words for use in RFCs to Indicate Requirement 
         Levels," BCP 14, RFC 2119, March 1997. 
    
   [8]   Haskin D., and E. Allen, "IP Version 6 over PPP," RFC 2472, 
         December 1998. 
   
   [9]   Narten T., et. al., " Privacy Extensions for Stateless Address  
         Autoconfiguration in IPv6," draft-ietf-ipv6-privacy-addrs-v2- 
         05, August 2006. 
    
9.2 Informative references 
    
   [10]  3GPP2 X.S0011-002-C v1.0, "cdma2000 Wireless IP Network  
         Standard: Simple IP and Mobile IP Access Services," September 
         2003. 
    
   [11]  3GPP TS 29.061 V6.4.0, "Interworking between the Public Land 
         Mobile Network (PLMN) Supporting packet based services and 
         Packet Data Networks (PDN) (Release 6)," April 2005. 
    
   [12]  Droms, E., et al., "Dynamic Host Configuration Protocol for 
         IPv6 (DHCPv6)," RFC 3315, July 2003. 
    
   [13]  3GPP TS 23.060 v6.8.0, "General Packet Radio Service (GPRS); 
         Service description; Stage 2 (Release 6)," March 2005. 
 
   [14]  Narten T., and C. Burton, "A Caution On The Canonical Ordering 
         Of Link-Layer Addresses," RFC 2469, December 1998. 
    
   [15]  Aboba, R., et. al., "Extensible Authentication Protocol," RFC 
         3748, June 2004. 
    
   [16]  Rivest, R., "The MD5 Message-Digest Algorithm," RFC 1321, April  
         1992. 
    
   [17]  Meyer, G., "The PPP Encryption Control Protocol (ECP)," RFC  
         1968, June 1996. 
    
Appendix A:  Global Scope Addresses 
    
      A node on the PPP link MUST create global unicast addresses either 
      through stateless or stateful address auto-configuration 
      mechanisms.  In the stateless address auto-configuration [3], the 
      node relies on sub-net prefixes advertised by the router via the 
 
 
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      Router Advertisement messages to obtain global unicast addresses 
      from an interface identifier.  In the stateful address auto-
      configuration, the host relies on a Stateful Server, like, DHCPv6 
      [12], to obtain global unicast addresses.  
    
Appendix B:  Changes from RFC-2472 
 
      The following changes were made from RFC-2472 "IPv6 over PPP": 
    
      -  Minor updates to sections 3 and 4 
    
      -  Updated the text in section 4.1 to include the reference to 
         Appendix A and minor text clarifications. 
    
      -  Removed the section 4.2 on IPv6-Compression-Protocol, based on 
         the IESG recommendation, and created a new standards track 
         draft to cover the negotiation of IPv6 datagram compression 
         protocol using IPV6CP. 
    
      -  Updated the text in Section 5 to: (a) allow the use of one or 
         more Interface-Identifiers generated by a peer, in addition to 
         the use of Interface-identifier negotiated between peers of the 
         link, in the creation of global unicast addresses for the local 
         PPP interface, and (b) identify cases against the DAD of 
         created non-link-local addresses. 
    
      -  Added new and updated references. 
    
      -  Added the Appendix A 
 
Authors' Addresses 
    
      Dimitry Haskin 
      Ed Allen 
       
      Srihari Varada (Editor) 
      TranSwitch Corporation 
      3 Enterprise Dr. 
      Shelton, CT 06484. US. 
    
      Phone: +1 203 929 8810 
      EMail: varada@txc.com 
 
IPR Notice 
    
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      to pertain to the implementation or use of the technology 
      described in this document or the extent to which any license 
 
 
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      under such rights might or might not be available; nor does it 
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