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RFC 3643

Fibre Channel (FC) Frame Encapsulation

Pages: 20
Proposed Standard

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Network Working Group                                           R. Weber
Request for Comments: 3643                                       Brocade
Category: Standards Track                                   M. Rajagopal
                                                    Broadcom Corporation
                                                           F. Travostino
                                                         Nortel Networks
                                                            M. O'Donnell
                                                                  McDATA
                                                                C. Monia
                                                          Nishan Systems
                                                               M. Merhar
                                                        Sun Microsystems
                                                           December 2003


                 Fibre Channel (FC) Frame Encapsulation

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 (2003).  All Rights Reserved.

Abstract

This document describes the common Fibre Channel (FC) frame encapsulation format and a procedure for the measurement and calculation of frame transit time through the IP network. This specification is intended for use by any IETF protocol that encapsulates FC frames.
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Table of Contents

1. Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Encapsulation Concepts . . . . . . . . . . . . . . . . . . . . 3 3. The FC Encapsulation Header. . . . . . . . . . . . . . . . . . 4 3.1. FC Encapsulation Header Format . . . . . . . . . . . . . 4 3.2. FC Encapsulation Header Validation . . . . . . . . . . . 7 3.2.1. Redundancy Based FC Encapsulation Header Validation. . . . . . . . . . . . . . . . 7 3.2.2. CRC Based FC Encapsulation Header Validation . . 7 4. Measuring Fibre Channel Frame Transit Time . . . . . . . . . . 8 5. The FC Frame . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.1. FC Frame Content . . . . . . . . . . . . . . . . . . . . 10 5.2. Bit and Byte Ordering. . . . . . . . . . . . . . . . . . 10 5.3. FC SOF and EOF . . . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations. . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . 13 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 Appendix A. Fibre Channel Bit and Byte Numbering Guidance . . . . 15 Appendix B. Encapsulating Protocol Requirements . . . . . . . . . 15 Appendix C. IANA Considerations . . . . . . . . . . . . . . . . . 16 Appendix D. Intellectual Property Rights Statement . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 20

1. Scope

This document describes common mechanisms for the transport of Fibre Channel frames over an IP network, including the encapsulation format and a mechanism for enforcing the Fibre Channel frame lifetime limits. Warning to Readers Familiar With Fibre Channel: Both Fibre Channel and IETF standards use the same byte transmission order. However, the bit and byte numbering is different. See Appendix A for guidance. The organization responsible for the Fibre Channel standards (INCITS Technical Committee T11) has determined that some functions and modes of operation are not interoperable to the degree required by the IETF (see FC-MI [8]). This document includes applicable T11 interoperability determinations in the form of restrictions on the use of this encapsulation mechanism.
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   Use of these mechanisms in an encapsulating protocol requires an
   additional document to specify the encapsulating protocol specific
   functionality and appropriate security considerations.  Because
   security considerations for this encapsulation depend on how it is
   used by encapsulating protocols, they are taken up in encapsulating
   protocol specific documents.

   Conventions used in this document

      The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
      NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
      in this document are to be interpreted as described in BCP 14, RFC
      2119 [2].

2. Encapsulation Concepts

The smallest unit of data transmission and routing in Fibre Channel (FC) is the frame. FC frames include a Start Of Frame (SOF), End Of Frame (EOF), and the contents of the Fibre Channel frame. The Fibre Channel frame includes a Cyclic Redundancy Check (CRC) code that provides error detection for the contents of the frame. FC frames are variable length. To facilitate transporting FC frames over an IP based transport such as TCP the native FC frame needs to be contained in (encapsulated in) a slightly larger structure as shown in Figure 1. +--------------------+ | Header | +--------------------+-----+ | SOF | f | +--------------------+ F r | | FC frame content | C a | +--------------------+ m | | EOF | e | +--------------------+-----+ Figure 1 - FC frame Encapsulation The format and content of an FC frame are described in the FC standards (e.g., FC-FS [3], FC-SW-2 [4], and FC-PI [5]). Of importance to this encapsulation is the FC requirement that all frames SHALL contain a CRC for detection of transmission errors.
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3. The FC Encapsulation Header

3.1. FC Encapsulation Header Format

Figure 2 shows the format of the required FC Encapsulation Header. W|------------------------------Bit------------------------------| o| | r| 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3| d|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| Protocol# | Version | -Protocol# | -Version | +---------------+---------------+---------------+---------------+ 1| | +----- Encapsulating Protocol Specific ----+ 2| | +-----------+-------------------+-----------+-------------------+ 3| Flags | Frame Length | -Flags | -Frame Length | +-----------+-------------------+-----------+-------------------+ 4| Time Stamp [Seconds] | +---------------------------------------------------------------+ 5| Time Stamp [Seconds Fraction] | +---------------------------------------------------------------+ 6| CRC | +---------------------------------------------------------------+ Figure 2 - FC Encapsulation Header Format The fields in the FC Encapsulation Header are defined as follows. Protocol#: The Protocol# field SHALL contain a number that indicates which encapsulating protocol is employing the FC Encapsulation. The values in the Protocol# field are assigned by IANA (see Appendix C). Version: The Version field SHALL contain 0x01 to indicate that this version of the FC Encapsulation is being used. All other values are reserved for future versions of the FC Encapsulation. -Protocol#: The -Protocol# field SHALL contain the one's complement of the contents of the Protocol# field. FC Encapsulation receivers SHOULD either validate the CRC or compare the Protocol# and - Protocol# fields to verify that an FC Encapsulation Header is being processed according to a policy defined by the encapsulating protocol.
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   -Version: The -Version field SHALL contain the one's complement of
      the contents of the Version field.  FC Encapsulation receivers
      SHOULD either validate the CRC or compare the Version and -Version
      fields to verify that an FC Encapsulation Header is being
      processed according to a policy defined by the encapsulating
      protocol.

   Encapsulating Protocol Specific: The usage of these words differs
      based on the contents of the Protocol# field, i.e., the usage of
      these words is defined by the encapsulating protocol that is
      employing this encapsulation.

   Flags: The Flags bits provide information about the usage of the
      FC Encapsulation Header as shown in Figure 3.

      |------------------------Bit--------------------------|
      |                                                     |
      |    0        1        2        3        4        5   |
      +--------------------------------------------+--------+
      |                  Reserved                  |  CRCV  |
      +--------------------------------------------+--------+

      Figure 3 -  Flags Field Format

   Reserved Flags bits: These bits are reserved for use by future
      versions of the FC Encapsulation and SHALL be set to zero on send.
      Encapsulating protocols employing the encapsulation described in
      this specification MAY require checking for zero on receive,
      however doing so has the potential to create incompatibilities
      with future versions of this encapsulation.  Changes in the usage
      of the Reserved Flags bits MUST be identified by changes in the
      contents of the Version field.  Encapsulating protocols employing
      the encapsulation described in this specification MUST NOT make
      use of the Reserved Flags bits in any fashion other than that
      described in this specification.

   CRCV (CRC Valid Flag): A CRCV bit value of one indicates that
      the contents of the CRC field are valid.  A CRCV bit value of zero
      indicates that the contents of the CRC field are invalid.  The
      value of the CRCV bit SHALL be constant for all FC Encapsulation
      Headers sent on a given connection.

   Frame Length: The Frame Length field contains the length of the
      entire FC Encapsulated frame including the FC Encapsulation Header
      and the FC frame (including SOF and EOF words).  This length is
      based on a unit of 32-bit words.  All FC frames are 32-bit-word-
      aligned and the FC Encapsulation Header is always word-aligned;
      therefore a32-bit word length is acceptable.
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   -Flags: The -Flags field SHALL contain the one's complement of the
      contents of the Flags field.  FC Encapsulation receivers SHOULD
      either validate the CRC or compare the Flags and -Flags fields to
      verify that an FC Encapsulation Header is being processed
      according to a policy defined by the encapsulating protocol.

   -Frame Length: The -Frame Length field SHALL contain the one's
      complement of the contents of the Frame Length field.  FC
      Encapsulation receivers SHOULD either validate the CRC or compare
      the Frame Length and -Frame Length fields to verify that an FC
      Encapsulation Header is being processed according to a policy
      defined by the encapsulating protocol.

   Time Stamp [Seconds]: The Time Stamp [Seconds] field contains zero
      or the number of seconds since 0 hour on 1 January 1900 at the
      time the FC Encapsulated frame is place in the outgoing data
      stream.

   Time Stamp [Seconds Fraction]: The Time Stamp [Second Fraction]
      field contains the fraction of the second at the time the FC
      Encapsulated frame is place in the outgoing data stream.  Non-
      significant low order bits may be set to zero.  Table 1 shows some
      example Time Stamp [Seconds Fraction] values.

      +------------+--------------------+
      |            |     Time Stamp     |
      |   Second   | [Seconds Fraction] |
      +------------+--------------------+
      | n.50000... |     0x80000000     |
      | n.25000... |     0x40000000     |
      | n.12500... |     0x20000000     |
      +------------+--------------------+

      Table 1  Example Time Stamp [Seconds Fraction] values

   Note that, since some time in 1968 (second 2,147,483,648) the most
   significant bit (bit 0 of Time Stamp [Seconds]) has been set and that
   the field will overflow some time in 2036 (second 4,294,967,296).
   Should FCIP be in use in 2036, some external means will be necessary
   to qualify time relative to 1900 and time relative to 2036 (and other
   multiples of 136 years).  There will exist a 200-picosecond interval,
   henceforth ignored, every 136 years when the 64-bit field will be 0,
   which by convention is interpreted as an invalid or unavailable
   timestamp.
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   The Time Stamp [Seconds] and Time Stamp [Seconds Fraction] words
   follow the in time format described in Simple Network Time Protocol
   (SNTP) Version 4 [9].  The contents of the Time Stamp [Seconds] and
   Time Stamp [Seconds Fraction] words SHALL be set as described in
   section 4.

   CRC: When the CRCV Flag bit is zero, the CRC field SHALL contain
   zero.  When the CRCV Flag bit is one, the CRC field SHALL contain a
   CRC for words 0 to 5 of the FC Encapsulation Header computed using
   the equations, polynomial, initial value, and bit order defined for
   Fibre Channel in FC-FS [3].  Using this algorithm, the bit order of
   the resulting CRC corresponds to that of FC-1 layer.  The CRC
   transmitted over the IP network shall correspond to the equivalent
   value converted to FC-2 format as specified in FC-FS.

3.2. FC Encapsulation Header Validation

Two mechanisms are provided for validating an FC Encapsulation Header: - Redundancy based - CRC based The two mechanisms address the needs of two different design and operating environments.

3.2.1. Redundancy Based FC Encapsulation Header Validation

Redundancy based validation of an FC Encapsulation Header relies on duplicated and one's complemented fields in the header. Encapsulating protocols that use redundancy based validation SHOULD define how receiving devices use one's complement fields to verify header validity. Header validation based on redundancy is a stepwise process in that the first word is validated, then the second, then the third and so on. A decision that a candidate header is not valid may be reached before the complete header is available.

3.2.2. CRC Based FC Encapsulation Header Validation

CRC based validation of an FC Encapsulation Header relies on a CRC located in the last word of the header. Header validation based on the CRC defined in section 3.1 requires computing the CRC for all bytes preceding the CRC word, and comparing the results to the CRC word's contents.
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4. Measuring Fibre Channel Frame Transit Time

To comply with FC-FS [3], an FC Fabric must specify and limit the lifetime of a frame. In an FC Fabric comprised of IP-connected elements, one component of the frame's lifetime is the time required to traverse the connection. To ensure that the total frame lifetime remains within the limits required by the FC Fabric, the encapsulation described in this specification contains provisions for recording the departure time of an encapsulated frame injected into a connection. If the encapsulated frame originator and recipient have access to aligned and synchronized time bases, the transit time through the IP network can then be computed. When originating an encapsulated frame, an entity that does not support transit time calculation SHALL always set the Time Stamp [Seconds] and Time Stamp [Seconds Fraction] fields to zero. When receiving an encapsulated frame, an entity that does not support transit time calculation SHALL ignore the contents of the Time Stamp words. The encapsulating protocol SHALL specify whether or not implementation support is required. The encapsulating protocol SHALL specify those conditions under which a received encapsulated frame MUST have its transit time checked before forwarding. Encapsulating and de-encapsulating entities that support this feature MUST have access to: a) An internal time base having the stability and resolution necessary to comply with the requirements of the encapsulating protocol specification; and b) A time base that is synchronized and aligned with the time base of other entities to which encapsulated frames may be sent or received. The encapsulating protocol specification MUST describe the synchronization and alignment procedure. With respect to its ability to measure and set transit time for encapsulated frames exchanged with another device, an entity is either in the Synchronized or Unsynchronized state. An entity is in the Unsynchronized state upon power-up and transitions to the Synchronized state once it has aligned its time base in accordance with the applicable encapsulating protocol specification. An entity MUST return to the Unsynchronized state if it is unable to maintain synchronization of its time base as required by the encapsulating protocol specification.
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   The policy for forwarding frames while in the Unsynchronized state
   SHALL be defined by the encapsulating protocol specification.

   If processing frames in the Unsynchronized state is permitted by the
   encapsulating protocol specification, the entity SHALL:

   a) When de-encapsulating a frame, ignore the Time Stamp words. For
      example, if a calculated transit time exceeds a value that could
      cause the frame to violate FC maximum time in transit limits, the
      encapsulating protocol may specify that the frame is to be
      discarded; and

   b) When encapsulating a frame set the Time Stamp [Seconds] and Time
      Stamp [Seconds Fraction] words to zero.  For example, an
      encapsulating protocol may specify that frames for which transit
      time cannot be determined are never to be forwarded over FC.

   When encapsulating a frame, an entity in the Synchronized state SHALL
   record the value of the time base in the Time Stamp [Seconds] and
   Time Stamp [Seconds Fraction] words in the encapsulation header.

   When de-encapsulating a frame, an entity in the Synchronized state
   SHALL:

   a) Test the Time Stamp words to determine if they contain a time as
      specified in [9].  If the time stamp is valid, the receiving
      entity SHALL compute the transit time by calculating the
      difference between its time base and the departure time recorded
      in the frame header.  The receiving entity SHALL process the
      calculated transit time and the de-encapsulated frame in
      accordance with the applicable encapsulating protocol
      specification; or

   b) If both Time Stamp words have a value of zero, the receiving
      entity SHALL de-encapsulate the frame without computing the
      transit time.  The disposition of the frame and any other actions
      by the recipient SHALL be defined by the encapsulating protocol
      specification.

   Note: For most purposes, communication between entities is possible
   only while in the Synchronized state.
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5. The FC Frame

5.1. FC Frame Content

NOTE: All uses of the words "character" or "characters" in this section refer to 8bit/10bit link encoding wherein each 8 bit "character" within a link frame is encoded as a 10 bit "character" for link transmission. These words do not refer to ASCII, Unicode, or any other form of text characters, although octets from such characters will occur as 8 bit "characters" for this encoding. This usage is employed here for consistency with the ANSI T11 standards that specify Fibre Channel. Figure 4 shows the structure of a general FC-2 frame format. +------------------+ | SOF | +------------------+ | FC frame content | +------------------+ | EOF | +------------------+ Figure 4 - General FC-2 Frame Format As shown in Figure 4, the FC frame content is defined as the data between the EOF and SOF delimiters (including the FC CRC) after conversion from FC-1 to FC-2 format as specified by FC-FS [3]. When Fibre Channel devices convert the FC frame content to the FC-0 physical transport, an encoding is applied to the FC frame content (e.g., 8b/10b encoding like that used in Gigbit Ethernet) for reasons that include redundancy and low level timing synchronization between sender and receiver. With the exceptions of SOF and EOF [3] all discussion of FC frame content in this document is at the 8-bit byte level, prior to the application of any such encoding. The 8-bit bytes in the FC frame content can be translated directly for transmission over an IP Network. However, the FC SOF and EOF employ special 10b characters that have no 8b equivalents. Therefore, special byte placement and 8-bit character encodings are required to represent SOF and EOF.

5.2. Bit and Byte Ordering

The Encapsulation Header, SOF, FC frame content (see section 5.1), and EOF are mapped to TCP using the big endian byte ordering, which corresponds to the standard network byte order or canonical form [7].
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5.3. FC SOF and EOF

As described in section 5.1, representation of FC SOF and EOF in an IP Network byte stream requires special formatting and 8-bit code definitions. Therefore, the encapsulated FC frame SHALL have the format shown in Figure 5. The redundancy of the SOF/EOF representation in the encapsulation format results from concerns that the information be protected from transmission errors. W|------------------------------Bit------------------------------| o| | r| 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3| d|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| SOF | SOF | -SOF | -SOF | +---------------+---------------+-------------------------------+ 1| | +----- FC frame content -----+ | | +---------------+---------------+-------------------------------+ n| EOF | EOF | -EOF | -EOF | +---------------+---------------+-------------------------------+ Figure 5 - FC Frame Encapsulation Format Note: The number of 8-bit bytes in the FC frame content is always a multiple of four. SOF: The SOF fields contain the encoded SOF value selected from table 2. +-------+------+-------+ +-------+------+-------+ | FC | SOF | | | FC | SOF | | | SOF | Code | Class | | SOF | Code | Class | +-------+------+-------+ +-------+------+-------+ | SOFf | 0x28 | F | | SOFi4 | 0x29 | 4 | | SOFi2 | 0x2D | 2 | | SOFn4 | 0x31 | 4 | | SOFn2 | 0x35 | 2 | | SOFc4 | 0x39 | 4 | | SOFi3 | 0x2E | 3 | +-------+------+-------+ | SOFn3 | 0x36 | 3 | +-------+------+-------+ Table 2 Translation of FC SOF values to SOF field contents -SOF: The -SOF fields contain the one's complement of the value in the SOF fields. Encapsulation receivers SHOULD validate the SOF field according to a policy defined by the encapsulating protocol.
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   EOF: The EOF fields contain the encoded EOF value selected from
      table 3.

   +-------+------+---------+   +--------+------+-------+
   |  FC   | EOF  |         |   |  FC    | EOF  |       |
   |  EOF  | Code |  Class  |   |  EOF   | Code | Class |
   +-------+------+---------+   +--------+------+-------+
   | EOFn  | 0x41 | 2,3,4,F |   | EOFdt  | 0x46 |   4   |
   | EOFt  | 0x42 | 2,3,4,F |   | EOFdti | 0x4E |   4   |
   | EOFni | 0x49 | 2,3,4,F |   | EOFrt  | 0x44 |   4   |
   | EOFa  | 0x50 | 2,3,4,F |   | EOFrti | 0x4F |   4   |
   +-------+------+---------+   +--------+------+-------+

   Table 3  Translation of FC EOF values to EOF field contents

   -EOF: The -EOF fields contain the one's complement of the value in
      the EOF fields.  Encapsulation receivers SHOULD validate the EOF
      field according to a policy defined by the encapsulating protocol.

   Note: FC-BB-2 [6] lists SOF and EOF codes not shown in table 2 and
   table 3 (e.g., SOFi1 and SOFn1).  However, FC-MI [8] identifies these
   codes as not interoperable, so they are not listed in this
   specification.

6. Security Considerations

This document describes the encapsulation format only. Actual use of this format in a encapsulating protocol requires an additional document to specify the encapsulating protocol functionality and appropriate security considerations. Because security considerations for this encapsulation depend on how it is used by encapsulating protocols, they SHALL be described in encapsulating protocol specific documents.

7. References

7.1. Normative References

[1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
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   [3]  Fibre Channel Framing and Signaling (FC-FS), ANSI
        INCITS.373:2003, October 27, 2003. Note: Published T11 standards
        are available from the INCITS online store
        http://www.incits.org, or the ANSI online store,
        http://www.ansi.org.

   [4]  Fibre Channel Switch Fabric -2 (FC-SW-2), ANSI NCITS.355:2001,
        December 12, 2002.  Note: Published T11 standards are available
        from the INCITS online store http://www.incits.org, or the ANSI
        online store, http://www.ansi.org.

   [5]  Fibre Channel Physical Interfaces (FC-PI), ANSI NCITS.352:2002,
        December 1, 2002.  Note: Published T11 standards are available
        from the INCITS online store http://www.incits.org, or the ANSI
        online store, http://www.ansi.org.

   [6]  Fibre Channel Backbone -2 (FC-BB-2), ANSI INCITS.372:2003, July
        25, 2003.  Note: Published T11 standards are available from the
        INCITS online store http://www.incits.org, or the ANSI online
        store, http://www.ansi.org.

   [7]  Narten, T. and C. Burton, "A Caution on The Canonical Ordering
        of Link-Layer Addresses", RFC 2469, December 1998.

7.2. Informative References

[8] Fibre Channel Methodologies for Interconnects (FC-MI), ANSI INCITS/TR-30:2002, November 1, 2002. Note: Published T11 standards are available from the INCITS online store http://www.incits.org, or the ANSI online store, http://www.ansi.org. [9] Mills, D., "Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI", RFC 2030, October 1996. [10] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [11] Rajagopal, M., Rodriguez, E., Weber, R., "Fibre Channel Over TCP/IP (FCIP)", Work in Progress. [12] Monia, C., et. al., "iFCP - A Protocol for Internet Fibre Channel Storage Networking", Work in Progress.
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8. Acknowledgements

The authors express their appreciation to Mr. Vi Chau (vchau1@cox.net) for his contributions to the design team that developed this document. Mr. Chau is no longer working in this technology. The authors are also grateful to Dr. David Black, Mr. Mallikarjun Chadalapaka, and Mr. Robert Elliott for their reviews of this specification.
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Appendix A. Fibre Channel Bit and Byte Numbering Guidance

Both Fibre Channel and IETF standards use the same byte transmission order. However, the bit and byte numbering is different. Fibre Channel bit and byte numbering can be observed if the data structure heading shown in Figure 6, is cut and pasted at the top of Figure 2 and Figure 5. W|------------------------------Bit------------------------------| o| | r|3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 | d|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| Figure 6 - Fibre Channel Data Structure Bit and Byte Numbering Fibre Channel bit numbering for the Flags field can be observed if the data structure heading shown in Figure 7, is cut and pasted at the top of Figure 3. |------------------------Bit--------------------------| | | | 31 30 29 28 27 26 | Figure 7 - Fibre Channel Flags Bit Numbering

Appendix B. Encapsulating Protocol Requirements

This appendix lists the requirements placed on the encapsulating protocols that employ this encapsulation. The requirements listed here are suggested or described elsewhere in this document, but their collection in this appendix serves to assist encapsulating protocol authors in meeting all obligations placed upon them. Encapsulating Protocol Specific Data Encapsulating protocols employing this encapsulation SHALL: - specify the IANA assigned number used in the Protocol# field - specify the contents of the Encapsulating Protocol Specific field Encapsulating protocols employing this encapsulation SHALL define the procedures and policies necessary for verifying that an FC Encapsulation Header is being processed.
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   Encapsulating protocols employing this encapsulation SHALL define the
   procedures and policies necessary for the detection of over age
   frames.  The items to be specified and the choices available to an
   encapsulating protocol specification are as follows:

   a) The encapsulating protocol requirements for measuring transit
      times.  The encapsulating protocol MAY allow implementation of
      transit time measurement to be optional.

   b) The requirements or guidelines for stability and resolution of the
      entity's time base.

   c) The procedure for synchronizing an entity's time base, including
      the criteria for entering the Synchronized and Unsynchronized
      states.

   d) The forwarding (or lack of forwarding) of frame traffic while in
      the Unsynchronized state.

      The specification MAY allow an entity in the Unsynchronized state
      to continue processing frame traffic.

   e) The procedure to be followed when frames are received that do not
      have a valid time stamp.

      The specification MAY allow such frames to be accepted by the
      entity.

   f) Requirements for setting and testing the transit time limit and
      the procedure to be followed when a received frame is discarded
      due to its transit time exceeding the limit.

Appendix C. IANA Considerations

The Protocol# (Protocol Number) field is an identifier number used to distinguish between the encapsulating protocols that employ this FC frame encapsulation. Values used in the Protocol# field are to be assigned from a new, separate registry that is maintained by IANA. All values in the Protocol# field are to be registered with and assigned by IANA with the following exceptions. - Protocol# value 0 should not be assigned until after all other values have been assigned. - Protocol# values 240-255 inclusive must be set aside for private use amongst cooperating systems.
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   Following the policies outlined in [10], Protocol# values not listed
   above are to be assigned only for Standards Track RFCs approved by
   the IESG.

   In addition to creating the FC Frame Encapsulation Protocol Number
   Registry, the standards action of this RFC allocates the following
   two values from the registry:

   -  Protocol# value 1 assigned to the FCIP (Fibre Channel Over TCP/
      IP) encapsulating protocol [11].

   -  Protocol# value 2 assigned to the iFCP (A Protocol for Internet
      Fibre Channel Storage Networking) encapsulating protocol [12].

Appendix D. Intellectual Property Rights Statement

The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director.
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Authors' Addresses

Ralph Weber ENDL Texas representing Brocade Comm. Suite 102 PMB 178 18484 Preston Road Dallas, TX 75252 USA Phone: +1 214 912 1373 EMail: roweber@ieee.org Murali Rajagopal Broadcom 16215 Alton Parkway PO Box 57013 Irvine, CA 92619 USA Phone: +1 949 450 8700 EMail: muralir@broadcom.com Franco Travostino Technology Center Nortel Networks, Inc. 600 Technology Park Billerica, MA 01821 USA Phone: +1 978 288 7708 EMail: travos@nortelnetworks.com Michael E. O'Donnell McDATA Corporation 4 McDATA Parkway Broomfield, Co. 80021 USA Phone +1 720 558 4142 Fax +1 720 558 8999 EMail: mike.o'donnell@mcdata.com
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   Charles Monia

   EMail: cmonia@pacbell.net


   Milan J. Merhar
   Sun Microsystems
   43 Nagog Park
   Acton, MA 01720
   USA

   Phone: +1 978 206 9124
   EMail: milan.merhar@sun.com
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Full Copyright Statement

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   Funding for the RFC Editor function is currently provided by the
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