Rfc3831
TitleTransmission of IPv6 Packets over Fibre Channel
AuthorC. DeSanti
DateJuly 2004
Format:TXT, HTML
Obsoleted byRFC4338
Status:PROPOSED STANDARD






Network Working Group                                         C. DeSanti
Request for Comments: 3831                                 Cisco Systems
Category: Standards Track                                      July 2004


            Transmission of IPv6 Packets over Fibre Channel

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document specifies the way of encapsulating IPv6 packets over
   Fibre Channel, and the method of forming IPv6 link-local addresses
   and statelessly autoconfigured addresses on Fibre Channel networks.

Table Of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Summary of Fibre Channel . . . . . . . . . . . . . . . . . . .  3
       2.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . .  3
       2.2.  Identifiers and Login. . . . . . . . . . . . . . . . . .  3
       2.3.  FC Levels and Frame Format . . . . . . . . . . . . . . .  4
       2.4.  Sequences and Exchanges  . . . . . . . . . . . . . . . .  5
   3.  IPv6 Capable Nx_Ports. . . . . . . . . . . . . . . . . . . . .  6
   4.  IPv6 Encapsulation . . . . . . . . . . . . . . . . . . . . . .  6
       4.1.  FC Sequence Format . . . . . . . . . . . . . . . . . . .  6
       4.2.  FC Classes of Service. . . . . . . . . . . . . . . . . .  8
       4.3.  FC Header Code Points. . . . . . . . . . . . . . . . . .  8
       4.4.  FC Network_Header. . . . . . . . . . . . . . . . . . . .  9
       4.5.  LLC/SNAP Header. . . . . . . . . . . . . . . . . . . . .  9
       4.6.  Bit and Byte Ordering. . . . . . . . . . . . . . . . . .  9
   5.  Maximum Transfer Unit. . . . . . . . . . . . . . . . . . . . . 10
   6.  Stateless Address Autoconfiguration. . . . . . . . . . . . . . 10
       6.1.  IPv6 Interface Identifier and Address Prefix . . . . . . 10
       6.2.  Generating an Interface ID from a Format 1
             N_Port_Name. . . . . . . . . . . . . . . . . . . . . . . 11
       6.3.  Generating an Interface ID from a Format 2
             N_Port_Name. . . . . . . . . . . . . . . . . . . . . . . 12



RFC 3831                IPv6 over Fibre Channel                July 2004


       6.4.  Generating an Interface ID from a Format 5
             N_Port_Name. . . . . . . . . . . . . . . . . . . . . . . 13
       6.5.  Generating an Interface ID from an EUI-64
             mapped N_Port_Name . . . . . . . . . . . . . . . . . . . 14
   7.  Link-Local Addresses . . . . . . . . . . . . . . . . . . . . . 15
   8.  Address Mapping for Unicast. . . . . . . . . . . . . . . . . . 15
   9.  Address Mapping for Multicast. . . . . . . . . . . . . . . . . 16
   10. Sequence Management. . . . . . . . . . . . . . . . . . . . . . 17
   11. Exchange Management. . . . . . . . . . . . . . . . . . . . . . 17
   12. Security Considerations. . . . . . . . . . . . . . . . . . . . 18
   13. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 18
   14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
       14.1.  Normative References. . . . . . . . . . . . . . . . . . 18
       14.2.  Informative References. . . . . . . . . . . . . . . . . 19
   A.  Transmission of a Broadcast FC Sequence over FC Topologies . . 20
   B.  Validation of the <N_Port_Name, N_Port_ID> mapping . . . . . . 21
   C.  Fibre Channel Bit and Byte Numbering Guidance. . . . . . . . . 22
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 23
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 24

1.  Introduction

   Fibre Channel (FC) is a high speed serial interface technology that
   supports several Upper Layer Protocols including Small Computer
   System Interface (SCSI) and IPv4 as specified in [IPFC].

   The purpose of this document is to specify a way of encapsulating IP
   version 6 [IPv6] over Fibre Channel and to describe a method of
   forming IPv6 link-local addresses [AARCH] and statelessly
   autoconfigured addresses on Fibre Channel networks.  This document
   also describes the content of the Source/Target Link-layer Address
   option used in Neighbor Discovery [DISC] when the messages are
   transmitted on a Fibre Channel network.

   Warning to readers familiar with Fibre Channel: both Fibre Channel
   and IETF standards use the same byte transmission order.  However,
   the bit numbering is different.  See Appendix C for guidance.

   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 [KEYWORDS].










RFC 3831                IPv6 over Fibre Channel                July 2004


2.  Summary of Fibre Channel

2.1.  Overview

   Fibre Channel (FC) is a gigabit speed network technology primarily
   used for Storage Networking.  Fibre Channel is standardized in the
   T11 Technical Committee of the InterNational Committee for
   Information Technology Standards (INCITS), an American National
   Standard Institute (ANSI) accredited standards committee.

   Fibre Channel devices are called Nodes.  Each Node has one or more
   Ports that connect to Ports of other devices.  Fibre Channel may be
   implemented using any combination of the following three topologies:

   -  a point-to-point link between two Ports;
   -  a set of Ports interconnected by a switching network called a
      Fabric, as defined in [FC-FS];
   -  a set of Ports interconnected with a loop topology, as defined in
      [FC-AL-2].

   A Node Port is more precisely called an N_Port.  A Node Port that is
   capable of operating in a loop topology using the loop specific
   protocols is designated as an NL_Port.  The term Nx_Port is used to
   generically indicate these two kinds of Node Port.

   A Fabric Port is more precisely called an F_Port.  A Fabric Port that
   is capable of operating in a loop topology using the loop specific
   protocols is designated as an FL_Port.  The term Fx_Port is used to
   generically indicate these two kinds of Fabric Port.

   From an IPv6 point of view, a Fibre Channel network, built with any
   combination of the FC topologies described above, is an IPv6 Link
   [IPv6].  IPv6-capable Nx_Ports are what [IPv6] calls Interfaces.

2.2.  Identifiers and Login

   Fibre Channel entities are identified by permanent 64 bit long
   Name_Identifiers.  [FC-FS] defines several formats of
   Name_Identifiers.  The value of the first four bits defines the
   format of a Name_Identifier.  These names are referred to in a more
   precise manner as follows:

   -  an Nx_Port's Name_Identifier is called N_Port_Name;
   -  an Fx_Port's Name_Identifier is called F_Port_Name;
   -  a Node's Name_Identifier is called Node_Name;
   -  a Fabric's Name_Identifier is called Fabric_Name.





RFC 3831                IPv6 over Fibre Channel                July 2004


   An Nx_Port connected to a Fibre Channel network is associated with
   two identifiers, its permanent N_Port_Name and a volatile 24 bit
   address called N_Port_ID.  The N_Port_Name is used to identify the
   Nx_Port, while the N_Port_ID is used for communications among
   Nx_Ports.

   Each Nx_Port acquires an N_Port_ID from the Fabric by performing a
   process called Fabric Login or FLOGI.  The FLOGI process is used also
   to negotiate several communications parameters between the Nx_Port
   and the Fabric, such as the receive data field size, which determines
   the maximum size of the Fibre Channel frames that may be transferred
   between the Nx_Port and the Fabric.

   Before effective communication may take place between two Nx_Ports,
   they must complete a process called Port Login or PLOGI.  The PLOGI
   process provides each Nx_Port with the other Nx_Port's N_Port_Name,
   and negotiates several communication parameters, such as the receive
   data field size, which determines the maximum size of the Fibre
   Channel frames that may be transferred between the two Nx_Ports.

   Both Fabric Login and Port Login may be explicit, i.e., performed
   using specific FC control messages (called Extended Link Services or
   ELS), or implicit, in which the parameters are specified by
   configuration or other methods.

2.3.  FC Levels and Frame Format

   [FC-FS] describes the Fibre Channel protocol using 5 different
   levels.  The FC-2 and FC-4 levels are relevant for this
   specification.  The FC-2 level defines the FC frame format, the
   transport services, and control functions necessary for information
   transfer.  The FC-4 level supports Upper Level Protocols, such as
   IPv4, IPv6 or SCSI.  The Fibre Channel frame format is depicted in
   figure 1.

    +-----+-----------+-----------+--------//-------+-----+-----+
    |     |           |         Data Field          |     |     |
    | SOF | FC Header |<--------------------------->| CRC | EOF |
    |     |           | Optional  | Frame           |     |     |
    |     |           | Header(s) | Payload         |     |     |
    +-----+-----------+-----------+--------//-------+-----+-----+

                    Fig. 1: Fibre Channel Frame Format

   The Start of Frame (SOF) and End of Frame (EOF) are special FC
   transmission words that act as frame delimiters.  The CRC is 4 octets
   long and uses the same 32-bit polynomial used in FDDI.




RFC 3831                IPv6 over Fibre Channel                July 2004


   The FC Header is 24 octets long and contains several fields
   associated with the identification and control of the Data Field.

   The Data Field is of variable size, ranging from 0 to 2112 octets,
   and includes the user data in the Frame Payload field, and Optional
   Headers.  The currently defined Optional Headers are:

   -  ESP_Header;
   -  Network_Header;
   -  Association_Header;
   -  Device_Header.

   The value of the SOF field determines the FC Class of service
   associated with the frame.  Five Classes of service are specified in
   [FC-FS].  They are distinguished primarily by the method of flow
   control between the communicating Nx_Ports and by the level of data
   integrity provided.  A given Fabric or Nx_Port may support one or
   more of the following Classes of service:

   -  Class 1: Dedicated physical connection with delivery confirmation;
   -  Class 2: Frame multiplexed service with delivery confirmation;
   -  Class 3: Datagram service;
   -  Class 4: Fractional bandwidth;
   -  Class 6: Reliable multicast via dedicated connections.

2.4.  Sequences and Exchanges

   An application level payload such as IPv6 is called Information Unit
   at the FC-4 level of Fibre Channel.  Each FC-4 Information Unit is
   mapped to an FC Sequence by the FC-2 level.  An FC Sequence consists
   of one or more FC frames related by the value of the Sequence_ID
   (SEQ_ID) field of the FC Header.

   The maximum data that may be carried by an FC frame is 2112 octets.
   The maximum usable frame size depends on the Fabric and Nx_Port
   implementations and is negotiated during the Login process.  Whenever
   an Information Unit to be transmitted exceeds this value, the FC-2
   level segments it into multiple FC frames, sent as a single Sequence.
   The receiving Nx_Port reassembles the Sequence of frames and delivers
   a reassembled Information Unit to the FC-4 level.  The Sequence Count
   (SEQ_CNT) field of the FC Header may be used to ensure frame
   ordering.

   Multiple Sequences may be related together as belonging to the same
   FC Exchange.  The Exchange is a mechanism used by two Nx_Ports to
   identify and manage an operation between them.  The Exchange is
   opened when the operation is started between the two Nx_Ports, and
   closed when the operation ends.  FC frames belonging to the same



RFC 3831                IPv6 over Fibre Channel                July 2004


   Exchange are related by the value of the Exchange_ID fields in the FC
   Header.  An Originator Exchange_ID (OX_ID) and a Responder
   Exchange_ID (RX_ID) uniquely identify the Exchange.

3.  IPv6 Capable Nx_Ports

   This specification requires an IPv6 capable Nx_Port to have the
   following properties:

   -  The format of its N_Port_Name MUST be one of 0x1, 0x2, 0x5, 0xC,
      0xD, 0xE, 0xF (see section 6.1).  IPv6 support for other
      Name_Identifier formats is outside the scope of this
      specification;
   -  It MUST support Class 3;
   -  It MUST support continuously increasing SEQ_CNT [FC-FS];
   -  It MUST be able to transmit and receive an FC-4 Information Unit
      at least 1304 octets long;
   -  It SHOULD support a receive data field size for Device_Data FC
      frames of at least 1024 octets.

4.  IPv6 Encapsulation

4.1.  FC Sequence Format

   An IPv6 packet is mapped to an Information Unit at the FC-4 level of
   Fibre Channel, which in turn is mapped to an FC Sequence by the FC-2
   level.  An FC Information Unit containing an IPv6 packet MUST carry
   the FC Network_Header [FC-FS] and the LLC/SNAP header [IEEE-LLC],
   resulting in the FC Information Unit format depicted in figure 2.






















RFC 3831                IPv6 over Fibre Channel                July 2004


    +---------------+---------------+---------------+---------------+
    |                                                               |
    +-                                                             -+
    |                        Network_Header                         |
    +-                         (16 octets)                         -+
    |                                                               |
    +-                                                             -+
    |                                                               |
    +---------------+---------------+---------------+---------------+
    |                        LLC/SNAP header                        |
    +-                          (8 octets)                         -+
    |                                                               |
    +---------------+---------------+---------------+---------------+
    |                                                               |
    +-                                                             -+
    /                          IPv6 Packet                          /
    /                                                               /
    +-                                                             -+
    |                                                               |
    +---------------+---------------+---------------+---------------+

            Fig. 2: FC Information Unit Mapping an IPv6 Packet

   The FC ESP_Header [FC-FS] MAY be used to secure the FC frames
   composing the FC Sequence. [AH] or [ESP] may be used to provide
   security at the IPv6 layer.  Other types of FC Optional Header MUST
   NOT be used in an IPv6 FC Sequence.

   Typically, a Sequence consists of more than one frame.  Only the
   first frame of the Sequence MUST include the FC Network_Header and
   the LLC/SNAP header.  The other frames MUST NOT include them, as
   depicted in figure 3.


                      First Frame of an IPv6 FC Sequence
   +-----------+-------------------+-----------------+-------//--------+
   | FC Header | FC Network_Header | LLC/SNAP header | First chunk of  |
   |           |                   |                 | the IPv6 Packet |
   +-----------+-------------------+-----------------+-------//--------+

                  Subsequent Frames of an IPv6 FC Sequence
             +-----------+-----------------//------------------+
             | FC Header | Additional chunk of the IPv6 Packet |
             +-----------+----------------//-------------------+

              Fig. 3: Optional Headers in an IPv6 FC Sequence





RFC 3831                IPv6 over Fibre Channel                July 2004


4.2.  FC Classes of Service

   This specification uses FC Class 3.  IPv6 packets carrying Neighbor
   Discovery [DISC] messages MUST be encapsulated in Class 3 FC frames.
   Other IPv6 packets SHOULD use Class 3 as well.  The use of other
   Classes of service is outside the scope of this specification.

4.3.  FC Header Code Points

   The fields of the Fibre Channel Header are depicted in figure 4.  The
   D_ID and S_ID fields contain respectively the destination N_Port_ID
   and the source N_Port_ID.  To encapsulate IPv6 over Fibre Channel the
   following code points MUST be used:

   -  R_CTL: 0x04 (Device_Data frame with Unsolicited Data Information
      Category [FC-FS])
   -  TYPE: 0x05 (IP over Fibre Channel)
   -  CS_CTL/Prio:  0x0
   -  DF_CTL: 0x20 (Network_Header) for the first FC frame of an IPv6
      Sequence, 0x00 for the following FC frames.  If the FC ESP_Header
      is used, then 0x60 for the first FC frame of an IPv6 Sequence,
      0x40 for the following FC frames.
   -  F_CTL, SEQ_ID, SEQ_CNT, OX_ID, RX_ID, Parameter: see section 10,
      section 11, and [FC-FS] for additional requirements.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |     R_CTL     |                      D_ID                     |
    +---------------+---------------+---------------+---------------+
    |  CS_CTL/Prio  |                      S_ID                     |
    +---------------+---------------+---------------+---------------+
    |     TYPE      |                     F_CTL                     |
    +---------------+---------------+---------------+---------------+
    |    SEQ_ID     |    DF_CTL     |            SEQ_CNT            |
    +---------------+---------------+---------------+---------------+
    |             OX_ID             |             RX_ID             |
    +---------------+---------------+---------------+---------------+
    |                           Parameter                           |
    +---------------+---------------+---------------+---------------+

                         Fig. 4: FC Header Format









RFC 3831                IPv6 over Fibre Channel                July 2004


4.4.  FC Network_Header

   The fields of the FC Network_Header are depicted in figure 5.  For
   use with IPv6 the N_Port_Names formats MUST be one of 0x1, 0x2, 0x5,
   0xC, 0xD, 0xE, 0xF.  IPv6 support for other Name_Identifier formats
   is outside the scope of this specification.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    +-                   Destination N_Port_Name                   -+
    |                                                               |
    +---------------------------------------------------------------+
    |                                                               |
    +-                     Source N_Port_Name                      -+
    |                                                               |
    +---------------------------------------------------------------+

                     Fig. 5: FC Network_Header Format

4.5.  LLC/SNAP Header

   The fields of the LLC/SNAP Header [IEEE-LLC] are depicted in figure
   6.  To encapsulate IPv6 over Fibre Channel the following code points
   MUST be used:

   -  DSAP: 0xAA
   -  SSAP: 0xAA
   -  CTRL: 0x03
   -  OUI:  0x00-00-00
   -  PID:  0x86-DD

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |     DSAP      |     SSAP      |     CTRL      |      OUI      |
    +---------------+---------------+---------------+---------------+
    |              OUI              |              PID              |
    +---------------+---------------+---------------+---------------+

                      Fig. 6: LLC/SNAP Header Format

4.6.  Bit and Byte Ordering

   IPv6 packets are mapped to the FC-4 level using the big-endian byte
   ordering that corresponds to the standard network byte order or
   canonical form.



RFC 3831                IPv6 over Fibre Channel                July 2004


5.  Maximum Transfer Unit

   The default MTU size for IPv6 [IPv6] packets over Fibre Channel is
   65280 octets.  This size may be reduced by a Router Advertisement
   [DISC] containing an MTU option that specifies a smaller MTU, or by
   manual configuration of each Nx_Port.  However, as required by
   [IPv6], the MTU MUST NOT be lower than 1280 octets.  If a Router
   Advertisement received on an Nx_Port has an MTU option specifying an
   MTU larger than 65280, or larger than a manually configured value,
   that MTU option MAY be logged to system management but MUST be
   otherwise ignored.

   As the default MTU size far exceeds the message sizes typically used
   in the Internet, an IPv6 over FC implementation SHOULD implement Path
   MTU Discovery [PMTUD], or at least maintain different MTU values for
   on-link and off-link destinations.

   For correct operation in a routed environment, it is critically
   important to configure an appropriate MTU option in Router
   Advertisements.

   For correct operation when mixed media (e.g., Ethernet and Fibre
   Channel) are bridged together, the smallest MTU of all the media must
   be advertised by routers in an MTU option.  If there are no routers
   present, this MTU must be manually configured in each node which is
   connected to a medium with a default MTU larger than the smallest
   MTU.

6.  Stateless Address Autoconfiguration

6.1.  IPv6 Interface Identifier and Address Prefix

   The IPv6 Interface ID [AARCH] for an Nx_Port is based on the EUI-64
   address [EUI64] derived from the Nx_Port's N_Port_Name.  The IPv6
   Interface Identifier is obtained by complementing the Universal/Local
   bit of the OUI field of the derived EUI-64 address.

   [FC-FS] specifies a method to map format 0x1 (IEEE 48 bit address),
   or 0x2 (IEEE Extended), or 0x5 (IEEE Registered) FC Name_Identifiers
   in EUI-64 addresses.  This allows the usage of these Name_Identifiers
   to support IPv6. [FC-FS] also defines EUI-64 mapped FC
   Name_Identifiers (formats 0xC, 0xD, 0xE, and 0xF), that are derived
   from an EUI-64 address.  It is possible to reverse this address
   mapping to obtain the original EUI-64 address in order to support
   IPv6.






RFC 3831                IPv6 over Fibre Channel                July 2004


   Stateless address autoconfiguration MUST be performed as specified in
   [ACONF].  An IPv6 Address Prefix used for stateless address
   autoconfiguration of an Nx_Port MUST have a length of 64 bits.

6.2.  Generating an Interface ID from a Format 1 N_Port_Name

   The Name_Identifier format 0x1 is depicted in figure 7.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|         0x000         |              OUI              |
    +-------+-------+---------------+---------------+---------------+
    |      OUI      |                      VSID                     |
    +---------------+---------------+---------------+---------------+

                    Fig. 7: Format 0x1 Name_Identifier

   The EUI-64 address derived from this Name_Identifier has the format
   depicted in figure 8 [FC-FS].

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         OUI with complemented U/L bit         |0 0 0 1|  VSID |
    +---------------+---------------+-------+-------+-------+-------+
    |                   VSID                |         0x000         |
    +---------------+---------------+-------+-------+---------------+

         Fig. 8: EUI-64 Address from a Format 0x1 Name_Identifier

   The IPv6 Interface Identifier is obtained from this EUI-64 address by
   complementing the U/L bit in the OUI field.  So the OUI in the IPv6
   Interface ID is exactly as in the FC Name_Identifier.  The resulting
   IPv6 Interface Identifier has local scope [AARCH] and the format
   depicted in figure 9.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      OUI                      |0 0 0 1|  VSID |
    +---------------+---------------+-------+-------+-------+-------+
    |                   VSID                |         0x000         |
    +---------------+---------------+-------+-------+---------------+

        Fig. 9: IPv6 Interface ID from a Format 0x1 Name_Identifier





RFC 3831                IPv6 over Fibre Channel                July 2004


   As an example, the FC Name_Identifier 0x10-00-34-63-46-AB-CD-EF
   generates the IPv6 Interface Identifier 3463:461A:BCDE:F000.

6.3.  Generating an Interface ID from a Format 2 N_Port_Name

   The Name_Identifier format 0x2 is depicted in figure 10.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 1 0|    Vendor Specific    |              OUI              |
    +-------+-------+---------------+---------------+---------------+
    |      OUI      |                      VSID                     |
    +---------------+---------------+---------------+---------------+

                    Fig. 10: Format 0x2 Name_Identifier

   The EUI-64 address derived from this Name_Identifier has the format
   depicted in figure 11 [FC-FS].

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         OUI with complemented U/L bit         |0 0 1 0|  VSID |
    +---------------+-----------------------+-------+-------+-------+
    |                   VSID                |    Vendor Specific    |
    +---------------+-----------------------+-------+---------------+

         Fig. 11: EUI-64 Address from a Format 0x2 Name_Identifier

   The IPv6 Interface Identifier is obtained from this EUI-64 address by
   complementing the U/L bit in the OUI field.  So the OUI in the IPv6
   Interface ID is exactly as in the FC Name_Identifier.  The resulting
   IPv6 Interface Identifier has local scope [AARCH] and the format
   depicted in figure 12.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      OUI                      |0 0 1 0|  VSID |
    +---------------+-----------------------+-------+-------+-------+
    |                   VSID                |    Vendor Specific    |
    +---------------+-----------------------+-------+---------------+

       Fig. 12: IPv6 Interface ID from a Format 0x2 Name_Identifier

   As an example, the FC Name_Identifier 0x27-89-34-63-46-AB-CD-EF
   generates the IPv6 Interface Identifier 3463:462A:BCDE:F789.



RFC 3831                IPv6 over Fibre Channel                July 2004


6.4.  Generating an Interface ID from a Format 5 N_Port_Name

   The Name_Identifier format 0x5 is depicted in figure 13.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 1 0 1|                      OUI                      |  VSID |
    +-------+-------+---------------+---------------+-------+-------+
    |                             VSID                              |
    +---------------+---------------+---------------+---------------+

                    Fig. 13: Format 0x5 Name_Identifier

   The EUI-64 address derived from this Name_Identifier has the format
   depicted in figure 14 [FC-FS].

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         OUI with complemented U/L bit         |0 1 0 1|  VSID |
    +---------------+---------------+---------------+-------+-------+
    |                             VSID                              |
    +---------------+---------------+---------------+---------------+

         Fig. 14: EUI-64 Address from a Format 0x5 Name_Identifier

   The IPv6 Interface Identifier is obtained from this EUI-64 address
   complementing the U/L bit in the OUI field.  So the OUI in the IPv6
   Interface ID is exactly as in the FC Name_Identifier.  The resulting
   IPv6 Interface Identifier has local scope [AARCH] and the format
   depicted in figure 15.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      OUI                      |0 1 0 1|  VSID |
    +---------------+---------------+---------------+-------+-------+
    |                             VSID                              |
    +---------------+---------------+---------------+---------------+

       Fig. 15: IPv6 Interface ID from a Format 0x5 Name_Identifier

   As an example, the FC Name_Identifier 0x53-46-34-6A-BC-DE-F7-89
   generates the IPv6 Interface Identifier 3463:465A:BCDE:F789.






RFC 3831                IPv6 over Fibre Channel                July 2004


6.5.  Generating an Interface ID from an EUI-64 mapped N_Port_Name

   The EUI-64 mapped Name_Identifiers formats (formats 0xC through 0xF)
   are derived from an EUI-64 address by compressing the OUI field of
   such addresses.  The compression is performed by removing from the
   OUI the Universal/Local and Individual/Group bits, and by putting
   bits 0 to 5 of the OUI in the first octet of the Name_Identifier, and
   bits 8 to 23 of the OUI in the second and third octet of the
   Name_Identifier, as shown in figure 16.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |1 1| OUI[0..5] |           OUI[8..23]          |      VSID     |
    +---+-----------+---------------+---------------+---------------+
    |                             VSID                              |
    +---------------+---------------+---------------+---------------+

              Fig. 16: EUI-64 Mapped Name_Identifiers Format

   The EUI-64 address used to generate the Name_Identifier shown in
   figure 16 has the format depicted in figure 17.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | OUI[0..5] |0 0|           OUI[8..23]          |      VSID     |
    +-----------+---+---------------+---------------+---------------+
    |                             VSID                              |
    +---------------+---------------+---------------+---------------+

       Fig. 17: EUI-64 Address from an EUI-64 Mapped Name_Identifier

   The IPv6 Interface Identifier is obtained from this EUI-64 address by
   complementing the U/L bit in the OUI field.  The resulting IPv6
   Interface Identifier has global scope [AARCH] and the format depicted
   in figure 18.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | OUI[0..5] |1 0|           OUI[8..23]          |      VSID     |
    +-----------+---+---------------+---------------+---------------+
    |                             VSID                              |
    +---------------+---------------+---------------+---------------+

     Fig. 18: IPv6 Interface ID from an EUI-64 Mapped Name_Identifier




RFC 3831                IPv6 over Fibre Channel                July 2004


   As an example, the FC Name_Identifier 0xCD-63-46-AB-01-25-78-9A
   generates the IPv6 Interface Identifier 3663:46AB:0125:789A.

7.  Link-Local Addresses

   The IPv6 link-local address [AARCH] for an Nx_Port is formed by
   appending the Interface Identifier, as defined in section 6, to the
   prefix FE80::/64.  The resulting address is depicted in figure 19.

      10 bits            54 bits                  64 bits
    +----------+-----------------------+----------------------------+
    |1111111010|         (zeros)       |    Interface Identifier    |
    +----------+-----------------------+----------------------------+

                  Fig. 19: IPv6 link-local Address Format

8.  Address Mapping for Unicast

   An Nx_Port has two kinds of Fibre Channel addresses:

   -  a non-volatile 64-bit address, called N_Port_Name;
   -  a volatile 24-bit address, called N_Port_ID.

   The N_Port_Name is used to uniquely identify the Nx_Port, while the
   N_Port_ID is used to route frames to the Nx_Port.  Both FC addresses
   are required to resolve an IPv6 unicast address.  The fact that the
   N_Port_ID is volatile implies that an Nx_Port MUST validate the
   mapping between its N_Port_Name and N_Port_ID when certain Fibre
   Channel events occur (see Appendix B).

   The procedure for mapping IPv6 unicast addresses into Fibre Channel
   link-layer addresses uses the Neighbor Discovery Protocol [DISC].
   The Source/Target Link-layer Address option has the format depicted
   in figure 20 when the link layer is Fibre Channel.

     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 = 2   |           Reserved            |
    +---------------+---------------+---------------+---------------+
    |                                                               |
    +-                         N_Port_Name                         -+
    |                                                               |
    +---------------+---------------+---------------+---------------+
    |   Reserved    |                   N_Port_ID                   |
    +---------------+---------------+---------------+---------------+

    Fig. 20: Source/Target Link-layer Address option for Fibre Channel



RFC 3831                IPv6 over Fibre Channel                July 2004


   Type:            1 for Source Link-layer address.
                    2 for Target Link-layer address.

   Length:          2 (in units of 8 octets).

   N_Port_Name:     This field contains the Nx_Port's N_Port_Name.
   N_Port_ID:       This field contains the Nx_Port's N_Port_ID.

   Reserved fields MUST be zero when transmitting, and MUST be ignored
   when receiving.

9.  Address Mapping for Multicast

   By default, all best-effort IPv6 multicast packets MUST be mapped to
   FC Sequences addressed to the broadcast N_Port_ID 0xFF-FF-FF.  In
   particular, datagrams addressed to all-nodes multicast address,
   all-routers multicast address, and solicited-node multicast addresses
   [AARCH] MUST be sent as Class 3 FC Sequences addressed to the
   broadcast N_Port_ID 0xFF-FF-FF.  In this case, the Destination
   N_Port_Name field of the FC Network_Header MUST be set to the value
   0x10-00-FF-FF-FF-FF-FF-FF.  Appendix A specifies how to transmit a
   Class 3 broadcast FC Sequence over various Fibre Channel topologies.

   An Nx_Port supporting IPv6 MUST be able to map a received broadcast
   Class 3 Device_Data FC frame to an implicit Port Login context in
   order to handle IPv6 multicast packets.  The receive data field size
   of this implicit Port Login MUST be the same across all the Nx_Ports
   connected to the same Fabric, otherwise FC broadcast transmission
   does not work.  In order to reduce the need for FC Sequence
   segmentation, the receive data field size of this implicit Port Login
   SHOULD be 1024 octets.  This receive data field size requirement
   applies to broadcast Device_Data FC frames, not to ELSs.

   Receiving an FC Sequence carrying an IPv6 multicast packet MAY
   trigger some additional processing by the Nx_Port if that IPv6 packet
   requires a unicast reply.  In this case, if a valid Port Login to the
   Nx_Port that sent the IPv6 multicast packet does not exist, the
   Nx_Port MUST perform such a Port Login, and then use it for the
   unicast IPv6 reply.  In the case of Neighbor Discovery messages
   [DISC], the N_Port_ID to which the Port Login is directed is taken
   from the N_Port_ID field of the Source/Target Link-layer Address
   option.

   As an example, an Nx_Port processes a received broadcast FC Sequence
   carrying an IPv6 multicast unsolicited router advertisement [DISC]
   simply by passing the carried IPv6 packet to the IPv6 layer.
   Instead, if a received broadcast FC Sequence carries an IPv6
   multicast solicitation message [DISC] requiring a unicast reply, and



RFC 3831                IPv6 over Fibre Channel                July 2004


   no valid Port Login exists with the Nx_Port sender of the multicast
   packet, then a Port Login MUST be performed in order to send the
   unicast reply message.  If a received broadcast FC Sequence carries
   an IPv6 multicast solicitation message [DISC] requiring a multicast
   reply, the reply is sent to the broadcast N_Port_ID 0xFF-FF-FF.

   Best-effort IPv6 multicast for other multicast group addresses MAY
   use Fibre Channel Multicast Groups [FC-FS], if supported by the
   particular FC topology and implementation.

10.  Sequence Management

   FC Sequences are REQUIRED to be non-streamed.  In order to avoid
   missing FC frame aliasing by Sequence_ID reuse, an Nx_Port supporting
   IPv6 is REQUIRED to use continuously increasing SEQ_CNT [FC-FS].
   Each Exchange MUST start with SEQ_CNT = 0 in the first frame, and
   every frame transmitted after that MUST increment the previous
   SEQ_CNT by one.  Any frames received from the other N_Port in the
   Exchange shall have no effect on the transmitted SEQ_CNT.

11.  Exchange Management

   To transfer IPv6 packets, each Nx_Port MUST have a dedicated Exchange
   for sending data to each Nx_Port in the network and a dedicated
   Exchange for receiving data from each Nx_Port.

   An Exchange Responder is not required to assign RX_IDs.  If an RX_ID
   of 0xFFFF is assigned, the Exchange Responder is identifying
   Exchanges based on S_ID / D_ID / OX_ID only.

   When an Exchange is created between two Nx_Ports for unicast IPv6
   packets, it remains active while the Nx_Ports are logged in with each
   other.  Each FC broadcast and ELS [FC-FS] SHOULD use a separate short
   lived Exchange.

   For IPv6, Exchanges MUST NOT transfer Sequence Initiative, because
   they are used in a unidirectional mode.  The Sequence Initiative bit
   in the F_CTL field of the FC Header [FC-FS] MUST be set to 0.

   The mechanism for aging or expiring exchanges based on activity,
   timeout, or other methods is outside the scope of this document.

   The Exchange Originator MAY terminate Exchanges by setting the F_CTL
   LS bit [FC-FS].  Exchanges MAY be torn down by the Exchange
   Originator or Exchange Responder by using the ABTS (Abort Sequence)
   protocol [FC-FS].  IPv6 Exchanges SHOULD NOT be terminated by Logout,
   since this may terminate active Exchanges on other FC-4s [FC-FS].




RFC 3831                IPv6 over Fibre Channel                July 2004


12.  Security Considerations

   IPv6 does not introduce any additional security concerns beyond those
   that already exist within the Fibre Channel protocols.  Zoning
   techniques based on FC Name Server masking (soft zoning) do not work
   with IPv6, because IPv6 over Fibre Channel does not use the FC Name
   Server.  The FC ESP_Header [FC-FS] may be used to secure the FC
   frames composing FC Sequences carrying IPv6 packets.  All the
   techniques defined to secure IPv6 traffic at the IPv6 layer may be
   used in a Fibre Channel environment.

13.  Acknowledgments

   The author would like to acknowledge the authors of [IPFC], [ETHER],
   and [IPv6-1394], since some part of this document has been derived
   from them, as well as the ANSI INCITS T11.3 Task Group members who
   reviewed this document.

14. References

14.1.  Normative References

   [FC-FS]     ANSI INCITS 373-2003, "Fibre Channel - Framing and
               Signaling (FC-FS)".

   [FC-AL-2]   ANSI INCITS 332-1999, "Fibre Channel - Arbitrated Loop-2
               (FC-AL-2)".

   [IPv6]      Deering, S. and R. Hinden, "Internet Protocol, Version 6
               (IPv6) Specification", RFC 2460, December 1998.

   [AARCH]     Hinden, R. and S. Deering, "Internet Protocol Version 6
               (IPv6) Addressing Architecture", RFC 3513, April 2003.

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

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

   [PMTUD]     McCann, J., Deering, S., and J. Mogul, "Path MTU
               Discovery for IP version 6", RFC 1981, August 1996.

   [IEEE-LLC]  IEEE Std 802-2001, "IEEE Standard for Local and
               Metropolitan Area Networks: Overview and Architecture".





RFC 3831                IPv6 over Fibre Channel                July 2004


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

14.2.  Informative References

   [IPFC]      Rajagopal, M., Bhagwat, R., and W. Rickard, "IP and ARP
               over Fibre Channel", RFC 2625, June 1999.

   [AH]        Kent, S. and R. Atkinson, "IP Authentication Header", RFC
               2402, November 1998.

   [ESP]       Kent, S. and R. Atkinson, "IP Encapsulating Security
               Payload (ESP)", RFC 2406, November 1998.

   [EUI64]     "Guidelines For 64-bit Global Identifier (EUI-64)",
               http://standards.ieee.org/db/oui/tutorials/EUI64.html

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

   [IPv6-1394] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets
               over IEEE 1394 Networks", RFC 3146, October 2001.





























RFC 3831                IPv6 over Fibre Channel                July 2004


A.  Transmission of a Broadcast FC Sequence over FC Topologies

A.1.  Point-to-Point Topology

   No particular mechanisms are required for this case.  The Nx_Port
   connected at the other side of the cable receives the broadcast FC
   Sequence having D_ID 0xFFFFFF.

A.2.  Private Loop Topology

   An NL_Port attached to a private loop MUST transmit a Class 3
   broadcast FC Sequence by using the OPN(fr) primitive signal
   [FC-AL-2].

   a) The source NL_Port first sends an Open Broadcast Replicate
      (OPN(fr)) primitive signal, forcing all the NL_Ports in the loop
      (except itself) to replicate the frames that they receive while
      examining the FC Header's D_ID field.
   b) The source NL_Port then removes the OPN(fr) signal when it returns
      to it.
   c) The source NL_Port then sends the Class 3 broadcast FC Sequence
      having D_ID 0xFFFFFF.

A.3.  Public Loop Topology

   An NL_Port attached to a public loop MUST NOT use the OPN(fr)
   primitive signal.  Rather, it MUST send the Class 3 broadcast FC
   Sequence having D_ID 0xFFFFFF to the FL_Port at AL_PA = 0x00
   [FC-AL-2].

   The Fabric propagates the broadcast to all other FC_Ports [FC-FS],
   including the FL_Port which the broadcast arrives on.  This includes
   all F_Ports, and other FL_Ports.

   Each FL_Port propagates the broadcast by using the primitive signal
   OPN(fr), in order to prepare the loop to receive the broadcast
   sequence.

A.4.  Fabric Topology

   An N_Port connected to an F_Port MUST transmit the Class 3 broadcast
   FC Sequence having D_ID 0xFFFFFF to the F_Port.  The Fabric
   propagates the broadcast to all other FC_Ports [FC-FS].








RFC 3831                IPv6 over Fibre Channel                July 2004


B.  Validation of the <N_Port_Name, N_Port_ID> mapping

B.1.  Overview

   At all times, the <N_Port_Name, N_Port_ID> mapping must be valid
   before use.

   After an FC link interruption occurs, the N_Port_ID of an Nx_Port may
   change, as well as the N_Port_IDs of all other Nx_Ports that have
   previously performed Port Login with this Nx_Port.  Because of this,
   address validation is required after a LIP in a loop topology
   [FC-AL-2] or after NOS/OLS in a point-to-point topology [FC-FS].

   N_Port_IDs do not change as a result of Link Reset (LR) [FC-FS], thus
   address validation is not required in this case.

B.2.  FC Layer Address Validation in a Point-to-Point Topology

   No validation is required after LR.  In a point-to-point topology,
   NOS/OLS causes implicit Logout of each N_Port and after a NOS/OLS
   each N_Port must again perform a Port Login [FC-FS].

B.3.  FC Layer Address Validation in a Private Loop Topology

   After a LIP [FC-AL-2], an NL_Port must not transmit any data to
   another NL_Port until the address of the other port has been
   validated.  The validation consists of completing either ADISC or
   PDISC [FC-FS].

   For a requester, this specification prohibits PDISC and requires
   ADISC.  As a responder, an implementation may need to respond to both
   ADISC and PDISC for compatibility with other FC specifications.

   If the three FC addresses (N_Port_ID, N_Port_Name, Node_Name) of a
   logged remote NL_Port exactly match the values prior to the LIP, then
   any active Exchange with that NL_Port may continue.

   If any of the three FC addresses has changed, then the remote NL_Port
   must be logged out.

   If an NL_Port's N_Port_ID changes after a LIP, then all active logged
   in NL_Ports must be logged out.









RFC 3831                IPv6 over Fibre Channel                July 2004


B.4.  FC Layer Address Validation in a Public Loop Topology

   A FAN ELS may be sent by the Fabric to all known previously logged in
   NL_Ports following an initialization event.  Therefore, after a LIP
   [FC-AL-2], NL_Ports may wait for this notification to arrive, or they
   may perform an FLOGI.

   If the F_Port_Name and Fabric_Name contained in the FAN ELS or FLOGI
   response exactly match the values before the LIP and if the AL_PA
   [FC-AL-2] obtained by the NL_Port is the same as the one before the
   LIP, then the port may resume all Exchanges.  If not, then FLOGI must
   be performed with the Fabric and all logged in Nx_Ports must be
   logged out.

   A public loop NL_Port must perform the private loop validation as
   specified in section B.3 to any NL_Port on the local loop that has an
   N_Port_ID of the form 0x00-00-XX.

B.5.  FC Layer Address Validation in a Fabric Topology

   No validation is required after LR (link reset).

   After NOS/OLS, an N_Port must perform FLOGI.  If, after FLOGI, the
   N_Port's N_Port_ID, the F_Port_Name, and the Fabric_Name are the same
   as before the NOS/OLS, then the N_Port may resume all Exchanges.  If
   not, all logged in Nx_Ports must be logged out [FC-FS].

C.  Fibre Channel Bit and Byte Numbering Guidance

   Both Fibre Channel and IETF standards use the same byte transmission
   order.  However, the bit numbering is different.

   Fibre Channel bit numbering can be observed if the data structure
   heading shown in figure 21 is cut and pasted at the top of the
   figures present in this document.

       3                   2                   1                   0
     1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Fig. 21: Fibre Channel Bit Numbering










RFC 3831                IPv6 over Fibre Channel                July 2004


Author's Address

   Claudio DeSanti
   Cisco Systems, Inc.
   170 W. Tasman Dr.
   San Jose, CA 95134
   USA

   Phone: +1 408 853-9172
   EMail: cds@cisco.com









































RFC 3831                IPv6 over Fibre Channel                July 2004


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