Binary Lexical Octet Ad-hoc Transport
RFC 3252

Document Type RFC - Informational (April 2002; No errata)
Last updated 2013-03-02
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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.


   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",
   document are to be interpreted as described in BCP 14, RFC 2119

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

   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
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