Network Working Group                                         H. Kennedy
Request for Comments: 3252                                      Mimezine
Category: Informational                                     1 April 2002
                 Binary Lexical Octet Ad-hoc Transport
Status of this Memo
   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.
Copyright Notice
   Copyright (C) The Internet Society (2002).  All Rights Reserved.
Abstract
   This document defines a reformulation of IP and two transport layer
   protocols (TCP and UDP) as XML applications.
1.   Introduction
1.1. Overview
   This document describes the Binary Lexical Octet Ad-hoc Transport
   (BLOAT): a reformulation of a widely-deployed network-layer protocol
   (IP [RFC791]), and two associated transport layer protocols (TCP
   [RFC793] and UDP [RFC768]) as XML [XML] applications.  It also
   describes methods for transporting BLOAT over Ethernet and IEEE 802
   networks as well as encapsulating BLOAT in IP for gatewaying BLOAT
   across the public Internet.
1.2. Motivation
   The wild popularity of XML as a basis for application-level protocols
   such as the Blocks Extensible Exchange Protocol [RFC3080], the Simple
   Object Access Protocol [SOAP], and Jabber [JABBER] prompted
   investigation into the possibility of extending the use of XML in the
   protocol stack.  Using XML at both the transport and network layer in
   addition to the application layer would provide for an amazing amount
   of power and flexibility while removing dependencies on proprietary
   and hard-to-understand binary protocols.  This protocol unification
   would also allow applications to use a single XML parser for all
   aspects of their operation, eliminating developer time spent figuring
   out the intricacies of each new protocol, and moving the hard work of
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   parsing to the XML toolset.  The use of XML also mitigates concerns
   over "network vs. host" byte ordering which is at the root of many
   network application bugs.
1.3. Relation to Existing Protocols
   The reformulations specified in this RFC follow as closely as
   possible the spirit of the RFCs on which they are based, and so MAY
   contain elements or attributes that would not be needed in a pure
   reworking (e.g. length attributes, which are implicit in XML.)
   The layering of network and transport protocols are maintained in
   this RFC despite the optimizations that could be made if the line
   were somewhat blurred (i.e. merging TCP and IP into a single, larger
   element in the DTD) in order to foster future use of this protocol as
   a basis for reformulating other protocols (such as ICMP.)
   Other than the encoding, the behavioral aspects of each of the
   existing protocols remain unchanged.  Routing, address spaces, TCP
   congestion control, etc. behave as specified in the extant standards.
   Adapting to new standards and experimental algorithm heuristics for
   improving performance will become much easier once the move to BLOAT
   has been completed.
1.4. Requirement Levels
   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
   [RFC2119].
2.   IPoXML
   This protocol MUST be implemented to be compliant with this RFC.
   IPoXML is the root protocol REQUIRED for effective use of TCPoXML
   (section 3.) and higher-level application protocols.
   The DTD for this document type can be found in section 7.1.
   The routing of IPoXML can be easily implemented on hosts with an XML
   parser, as the regular structure lends itself handily to parsing and
   validation of the document/datagram and then processing the
   destination address, TTL, and checksum before sending it on to its
   next-hop.
   The reformulation of IPv4 was chosen over IPv6 [RFC2460] due to the
   wider deployment of IPv4 and the fact that implementing IPv6 as XML
   would have exceeded the 1500 byte Ethernet MTU.
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   All BLOAT implementations MUST use - and specify - the UTF-8 encoding
   of RFC 2279 [RFC2279].  All BLOAT document/datagrams MUST be well-
   formed and include the XMLDecl.
2.1. IP Description
   A number of items have changed (for the better) from the original IP
   specification.  Bit-masks, where present have been converted into
   human-readable values.  IP addresses are listed in their dotted-
   decimal notation [RFC1123].  Length and checksum values are present
   as decimal integers.
   To calculate the length and checksum fields of the IP element, a
   canonicalized form of the element MUST be used.  The canonical form
   SHALL have no whitespace (including newline characters) between
   elements and only one space character between attributes.  There
   SHALL NOT be a space following the last attribute in an element.
   An iterative method SHOULD be used to calculate checksums, as the
   length field will vary based on the size of the checksum.
   The payload element bears special attention.  Due to the character
   set restrictions of XML, the payload of IP datagrams (which MAY
   contain arbitrary data) MUST be encoded for transport. This RFC
   REQUIRES the contents of the payload to be encoded in the base-64
   encoding of RFC 2045 [RFC2045], but removes the requirement that the
   encoded output MUST be wrapped on 76-character lines.
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2.2. Example Datagram
   The following is an example IPoXML datagram with an empty payload:
   
   
   
   
   
   
   
3.   TCPoXML
   This protocol MUST be implemented to be compliant with this RFC.  The
   DTD for this document type can be found in section 7.2.
3.1. TCP Description
   A number of items have changed from the original TCP specification.
   Bit-masks, where present have been converted into human-readable
   values.  Length and checksum and port values are present as decimal
   integers.
   To calculate the length and checksum fields of the TCP element, a
   canonicalized form of the element MUST be used as in section 2.1.
   An iterative method SHOULD be used to calculate checksums as in
   section 2.1.
   The payload element MUST be encoded as in section 2.1.
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   The TCP offset element was expanded to a maximum of 255 from 16 to
   allow for the increased size of the header in XML.
   TCPoXML datagrams encapsulated by IPoXML MAY omit the  header
   as well as the  declaration.
3.2. Example Datagram
   The following is an example TCPoXML datagram with an empty payload:
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
4.   UDPoXML
   This protocol MUST be implemented to be compliant with this RFC.  The
   DTD for this document type can be found in section 7.3.
4.1. UDP Description
   A number of items have changed from the original UDP specification.
   Bit-masks, where present have been converted into human-readable
   values.  Length and checksum and port values are present as decimal
   integers.
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   To calculate the length and checksum fields of the UDP element, a
   canonicalized form of the element MUST be used as in section 2.1.  An
   iterative method SHOULD be used to calculate checksums as in section
   2.1.
   The payload element MUST be encoded as in section 2.1.
   UDPoXML datagrams encapsulated by IPoXML MAY omit the  header
   as well as the  declaration.
4.2. Example Datagram
   The following is an example UDPoXML datagram with an empty payload:
   
   
   
   
   
   
   
   
   
   
   
   
5.   Network Transport
   This document provides for the transmission of BLOAT datagrams over
   two common families of physical layer transport.  Future RFCs will
   address additional transports as routing vendors catch up to the
   specification, and we begin to see BLOAT routed across the Internet
   backbone.
5.1. Ethernet
   BLOAT is encapsulated in Ethernet datagrams as in [RFC894] with the
   exception that the type field of the Ethernet frame MUST contain the
   value 0xBEEF.  The first 5 octets of the Ethernet frame payload will
   be 0x3c 3f 78 6d 6c ("
   -->
   
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7.2.  TCPoXML DTD
   
   
   
   
   
   
   
   
   
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7.3.  UDPoXML DTD
   
   
   
   
   
   
   
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8. Security Considerations
   XML, as a subset of SGML, has the same security considerations as
   specified in SGML Media Types [RFC1874].  Security considerations
   that apply to IP, TCP and UDP also likely apply to BLOAT as it does
   not attempt to correct for issues not related to message format.
9.   References
   [JABBER]    Miller, J., "Jabber", draft-miller-jabber-00.txt,
               February 2002. (Work in Progress)
   [RFC768]    Postel, J., "User Datagram Protocol", STD 6, RFC 768,
               August 1980.
   [RFC791]    Postel, J., "Internet Protocol", STD 5, RFC 791,
               September 1981.
   [RFC793]    Postel, J., "Transmission Control Protocol", STD 7, RFC
               793, September 1981.
   [RFC894]    Hornig, C., "Standard for the Transmission of IP
               Datagrams over Ethernet Networks.", RFC 894, April 1984.
   [RFC1042]   Postel, J. and J. Reynolds, "Standard for the
               Transmission of IP Datagrams Over IEEE 802 Networks", STD
               43, RFC 1042, February 1988.
   [RFC1123]   Braden, R., "Requirements for Internet Hosts -
               Application and Support", RFC 1123, October 1989.
   [RFC1874]   Levinson, E., "SGML Media Types", RFC 1874, December
               1995.
   [RFC2003]   Perkins, C., "IP Encapsulation within IP", RFC 2003,
               October 1996.
   [RFC2045]   Freed, N. and N. Borenstein, "Multipurpose Internet Mail
               Extensions (MIME) Part One: Format of Internet Message
               Bodies", RFC 2045, November 1996.
   [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.
   [RFC2279]   Yergeau, F., "UTF-8, a transformation format of ISO
               10646", RFC 2279, January 1998.
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   [RFC2460]   Deering, S. and R. Hinden, "Internet Protocol, Version 6
               (IPv6) Specification", RFC 2460, December 1998.
   [RFC3080]   Rose, M., "The Blocks Extensible Exchange Protocol Core",
               RFC 3080, March 2001.
   [SOAP]      Box, D., Ehnebuske, D., Kakivaya, G., Layman, A.,
               Mendelsohn, N., Nielsen, H. F., Thatte, S. Winer, D.,
               "Simple Object Access Protocol (SOAP) 1.1" World Wide Web
               Consortium Note, May 2000 http://www.w3.org/TR/SOAP/
   [XML]       Bray, T., Paoli, J., Sperberg-McQueen, C. M., "Extensible
               Markup Language (XML)" World Wide Web Consortium
               Recommendation REC- xml-19980210.
               http://www.w3.org/TR/1998/REC-xml-19980210
10.  Author's Address
   Hugh Kennedy
   Mimezine
   1060 West Addison
   Chicago, IL 60613
   USA
   EMail: kennedyh@engin.umich.edu
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11.  Full Copyright Statement
   Copyright (C) The Internet Society (2002).  All Rights Reserved.
   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.
   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.
   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgement
   Funding for the RFC Editor function is currently provided by the
   Internet Society.
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