INTERNET-DRAFT M. Yevstifeyev
Intended Status: Experimental December 21, 2010
Expires: June 24, 2011
Extendable User Datagram Protocol
<draft-yevstifeyev-eudp-02>
Abstract
This document is a specification of Extendable User Datagram Protocol
(EUDP), which is based on User Datagram Protocol (UDP), but allows to
extend the header using options.
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the Trust Legal Provisions and are provided without warranty as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Description . . . . . . . . . . . . . . . . . . . . . 4
2.1. Lower Layer Protocols Considerations . . . . . . . . . . . 4
2.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1. Header . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.2. Fields . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.2.1. Source Port . . . . . . . . . . . . . . . . . . . 5
2.2.2.2. Destination Port . . . . . . . . . . . . . . . . 5
2.2.2.3. Data Offset . . . . . . . . . . . . . . . . . . . 5
2.2.2.4. Checksum . . . . . . . . . . . . . . . . . . . . 5
2.2.2.5. Options . . . . . . . . . . . . . . . . . . . . . 5
2.2.2.6. Padding . . . . . . . . . . . . . . . . . . . . . 6
2.3. Pre-Defined Options . . . . . . . . . . . . . . . . . . . . 6
2.3.1. 'No Operation' Option . . . . . . . . . . . . . . . . 6
2.3.2. 'End Of Options List' Option . . . . . . . . . . . . . 6
2.3.3. 'Echo Request' Option . . . . . . . . . . . . . . . . 7
2.3.4. 'Echo Response' Option . . . . . . . . . . . . . . . . 7
2.3.5. 'MD5 Digest' Option . . . . . . . . . . . . . . . . . 7
2.4. Pseudo Header . . . . . . . . . . . . . . . . . . . . . . . 8
2.5. Compatibility with UDP . . . . . . . . . . . . . . . . . . 8
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 9
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
4.1. EUDP Options Numbers Registry . . . . . . . . . . . . . . 10
4.2. EUDP Ports Registry . . . . . . . . . . . . . . . . . . . 10
4.3. IP Protocol Number Assignment . . . . . . . . . . . . . . 11
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. Normative References . . . . . . . . . . . . . . . . . . 12
5.2. Informative References . . . . . . . . . . . . . . . . . 12
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
UDP is one of the most widely-used transport-level protocol. One of
the things which makes it so popular is its simplicity. However in
some cases this causes lack of facilities, which can be provided by
other protocols, such as TCP (see RFC 793 [RFC793]) or DCCP (see RFC
4340 [RFC4340]). During the history of UDP some attempts have been
made to improve it by adding some features (for instance UDP-Lite
(see RFC 3828 [RFC3828])), but these proposals were too specific and
did not gain popularity.
EUDP, protocol, proposed by this document, is intended to be a
universal solution, which combines simplicity of UDP and
extensibility of TCP by adding an options space to UDP header.
1.1. Terminology
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 RFC 2119 [RFC2119].
The document uses the ABNF notation and core rules defined in RFC
5234 [RFC5234].
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2. Protocol Description
2.1. Lower Layer Protocols Considerations
EUDP is a transport-layer protocol, and the protocol directly under
it is IP. EUDP supports as IPv4, as IPv6 as lower-layer protocol. The
IP Protocol number to be used with EUDP is TBD1.
2.2. Packet Format
2.2.1. Header
The EUDP header is shown in the figure 1.
0 15 16 31
+----------------+----------------+
| Source Port |Destination Port|
+----------------+----------------+
| Data Offset | Checksum |
+----------------+----------------+
| |
: Options :
: :
: +----------------+
| | Padding |
+----------------+----------------+
| |
: Data :
: :
+----------------+----------------+
Figure 1
EUDP header is described in ABNF in the following way:
eudp_header = source_port
destination_port
offset
checksum
[options]
[padding]
data
source_port = 2(%x30-39)
destination_port = 2(%x30-39)
offset = 2(%x30-39)
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checksum = 2(%x30-39)
options = *option
option = <defined in Section 2.2.2>
padding = 1*%x00
data = *(%x00-FF)
2.2.2. Fields
2.2.2.1. Source Port
Source Port (16 bits) - REQUIRED field which is defied and is to be
used as described in UDP specification - RFC 768 [RFC768]. EUDP uses
the same port set as UDP.
2.2.2.2. Destination Port
Destination Port (16 bits) - REQUIRED field which is defied and is to
be used as described in UDP specification - RFC 768 [RFC768]. EUDP
uses the same port set as UDP.
2.2.2.3. Data Offset
Data Offset (16 bits) - REQUIRED field which is the number of 32 bit
words in the EUDP Header. The EUDP header (even one including
options) MUST be an integral number of 32 bits long.
2.2.2.4. Checksum
Checksum (16 bits) - REQUIRED field which is defied and is to be used
as described in UDP specification - RFC 768 [RFC768].
2.2.2.5. Options
Options (variable length) - OPIONAL field. Options may occupy space
at the end of the EUDP header and are a multiple of 8 bits in length.
All options are included in the checksum. An option may begin on any
octet boundary. There are two cases for the format of an option:
a) a single octet of option-kind.
b) an octet of option-kind, an octet of option-length, and the
actual option-data octets. The option-length counts the two octets of
option-kind and option-length as well as the option-data octets. Note
that the list of options may be shorter than the data offset field
might imply. The content of the header beyond the End Of Options List
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option must be header padding (i.e., zero).
EUDP options are described in ABNF in the following way:
option = octet_option / multioctet_option
octet_option = option_kind
multioctet_option = option_kind option_length option_value
option_kind = %x00-FF
option_length = %x00-FF
option_value = 1*(%x00-FF)
All options can be mandatory or optional for support. EUDP nodes MUST
support all mandatory options. Support of optional options is
OPTIONAL.
Pre-defied options are specified in Section 2.3.
2.2.2.6. Padding
Padding (variable length) - OPTIONAL field. The EUDP header padding
is used to ensure that the EUDP header ends and data begins on a 32
bit boundary. The padding is composed of zeros.
2.3. Pre-Defined Options
This section specifies pre-defined EUDP options.
2.3.1. 'No Operation' Option
+--------+
| Kind=0 |
+--------+
This option may be used between options, for example, to align the
beginning of a subsequent option on a word boundary.
The option is mandatory for support.
2.3.2. 'End Of Options List' Option
+--------+
| Kind=1 |
+--------+
This option code indicates the end of the option list. This might not
coincide with the end of the EUDP header according to the Data Offset
field. This is used at the end of all options, not the end of each
option, and need only be used if the end of the options would not
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otherwise coincide with the end of the EUDP header.
The option is mandatory for support.
2.3.3. 'Echo Request' Option
+--------+--------+-------//-------+
| Kind=2 | Length | Data |
+--------+--------+-------//-------+
The 'Echo Request' option is used to provide the possibility of echo
debugging using the EUDP. The 'Data' part of option may consist of
arbitrary octets.
The option is mandatory for support.
2.3.4. 'Echo Response' Option
+--------+--------+-------//-------+
| Kind=3 | Length | Data |
+--------+--------+-------//-------+
The 'Echo Response' option is used to answer the packets with 'Echo
Request' option. The packet consisting 'Echo Response' option SHOULD
be send after receiving any EUDP packet with 'Echo Request' option.
The 'Data' part of the option MUST be the same as in received 'Echo
Request' option.
The option is mandatory for support.
2.3.5. 'MD5 Digest' Option
+---------+---------+-------------------+
| Kind=4 |Length=18| MD5 digest... |
+---------+---------+-------------------+
| |
+---------------------------------------+
| |
+---------------------------------------+
| |
+-------------------+-------------------+
| |
+-------------------+
The 'MD5 Digest' option contains the MD5 [RFC1321] hash of EUDP
packet, which is always 16 bytes long. While calculating the digest,
the value of digest MUST be treated as zeroes.
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The option is optional for support.
2.4. Pseudo Header
EUDP does not use pseudo header.
2.5. Compatibility with UDP
The applications which use UDP can safely use EUDP with no options
instead.
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3. Security Considerations
Generic security issues for UDP concern EUDP as well.
Additional security can be provided by additional options. This
document does not define such options.
UDP itself does not provide any authentication features. Such
features can be provided by additional options, which are not defined
by this document.
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4. IANA Considerations
4.1. EUDP Options Numbers Registry
IANA is asked to create and maintain the registry named 'EUDP Options
Numbers Registry', which consists of 4 values: Option Kind, Option
Length, Support Criteria, Description and Reference. Option Kind
value is integer; values from 0 to 255 are assigned. Option length
may be omitted (for one octet options), be stated as an integer or
'variable'. Support Criteria can be assigned as 'Mandatory' and
'Optional'. The initial values are given below; assignments to this
registry are to be made following the RFC Required policies
[RFC5226].
The Option Kind 0 is assigned for No Operation option. No Option
Length value is assigned for it. The Support Criteria for this option
is 'mandatory'. The Reference document is this RFC xxxx.
The Option Kind 1 is assigned for End Of Options List option. No
Option Length value is assigned for it. The Support Criteria for this
option is 'mandatory'. The Reference document is this RFC xxxx.
The Option Kind 2 is assigned for Echo Request option. The Option
Length value 'variable' is assigned for it. The Support Criteria for
this option is 'mandatory'. The Reference document is this RFC xxxx.
The Option Kind 3 is assigned for Echo Response option. The Option
Length value 'variable' is assigned for it. The Support Criteria for
this option is 'mandatory'. The Reference document is this RFC xxxx.
The Option Kind 4 is assigned for MD5 Digest option. The Option
Length value 18 is assigned for it. The Support Criteria for this
option is 'optional'. The Reference document is this RFC xxxx.
The Option Kinds 5-253 are available for assignment.
The Option Kind 254 is permanently reserved for experimentation
purposes.
The Option Kind 255 is permanently reserved for future use.
[RFC Editor: Please replace xxxx with assigned RFC number]
4.2. EUDP Ports Registry
As EUDP uses the same port set as UDP, IANA is asked to mark that all
assigned UDP ports can be used with EUDP as well.
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4.3. IP Protocol Number Assignment
IANA has assigned the IP protocol number TBD1 to be used with EUDP.
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5. References
5.1. Normative References
[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234, January
2008.
5.2. Informative References
[RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, September 1981.
[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E.,
Ed., and G. Fairhurst, Ed., "The Lightweight User
Datagram Protocol (UDP-Lite)", RFC 3828, July 2004.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
Congestion Control Protocol (DCCP)", RFC 4340, March
2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
Author's Addresses
Mykyta Yevstifeyev
8 Kuzovkov St., flat 25,
Kotovsk, Ukraine
EMail: evnikita2@gmail.com
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