Internet DRAFT - draft-rosenau-prenegotiated-options
draft-rosenau-prenegotiated-options
Network Working Group M. Rosenau
Internet-Draft December 21, 2017
Intended status: Experimental
Expires: June 24, 2018
Prenegotiated options for IP, ICMP and TCP headers
draft-rosenau-prenegotiated-options-00
Abstract
In many cases (example: PPTP [RFC2637]) a data transfer between two
hosts is initiated by using "generic" protocols (in the case of PPTP
this is UDP) and later on "special" protocols (in the case of PPTP
this is GRE) are used.
The drawback in this case is that the IANA has to assign protcol
numbers (in the case of GRE this is 47)
The same is true for TCP header "options" and ICMP packet "types".
To avoid assigning numbers by the IANA this document proposes to
reserve a range of protocol numbers for "negotiation" instead.
During the phase using "generic" protocols the two hosts negotiate a
protocol number in that range.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 24, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Internet-Draft PrenegotiatedOptions December 2017
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described in the Simplified BSD License.
1. Introduction
Currently about 140 different layer 4 protocol numbers are assigned
by the IANA to be used in the "next header" field (IPv6; IPv4:
"protocol" field). Only 250 different protocol numbers are
supported.
Because of the development of new protocols the number of possible
values might be exceeded soon.
Furthermore the IANA has the work to assign a protocol number, TCP
option or ICMP packet type.
This document proposes to assign a range of numbers for
"negotiation".
This means that in a data transfer between two hosts first negotiate
to use a certain number from the range reserved from "negotiation"
instead of using a pre-defined protocol number.
2. Current situation
Currently the IANA is assigning protocol numbers, TCP options and
ICMP packet types of all "non-experimental" protocols.
However in many situations a data transfer is initiated not using
pre-assigned numbers. The following example shows a PPTP session:
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Host A Host B
| |
+---------- UDP --------->|
| |
|<-------- UDP -----------+
| |
+--------- GRE ---------->|
| (Packet type = 47) |
| |
|<-------- GRE -----------+
| (Packet type = 47) |
| ... |
Figure 1: Sequence: PPTP
3. Proposed future behaviour
If no assigned number is necessary for the first data packets both
hosts should first negotiate a protocol number from a certain range
to be assigned by the IANA.
It is not necessary that both hosts negotiate one value; instead it
is also possible that both hosts tell each other which value to be
used. For each packet the value desired by the destination host is
used.
The following example shows some EXample Protocol (EXP) using this
approach:
Host A Host B
| |
+---------- UDP ----------->|
| (Desired value = 240) |
| |
|<--------- UDP ------------+
| (Desired value = 241) |
| |
+---------- EXP ----------->|
| (Packet type = 241) |
| |
|<--------- EXP ------------+
| (Packet type = 240) |
| ... |
Figure 2: Sequence: Future protocol
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4. Proposed ranges
4.1. Most use cases
RFC 4727 [RFC4727] specifies values 253 and 254 to be used for
"experimental" purposes in the following fields:
o IPv4 "protocol" field
o IPv6 "next header" field
o ICMPv4 "type" field
o TCP "option" type
Because the range immediately before the number 253 is unassigned for
all of these fields this document proposes the range from 240 to 252
for use with negotiation.
4.2. ICMPv6 types
RFC 4727 [RFC4727] specifies values 100 and 101 to be used for
"experimental" error codes in the ICMPv6 "type" field.
Because the range before the number 100 is unassigned this document
proposes the range from 90 to 99 to be used for "negotiated" error
codes.
RFC 4727 [RFC4727] specifies values 200 and 201 to be used for
"experimental" non-error packet types in the ICMPv6 "type" field.
Because the range before the number 200 is unassigned this document
proposes the range from 190 to 199 to be used for "negotiated" non-
error packets.
4.3. IPv6 destination options
Currently this document does not propose the use of negotiated IPv6
destination options.
4.4. When not to use negotiated values
Because these options must be negotiated between two hosts these
options MUST NOT be used whenever more than two hosts must understand
these options.
Examples for this situation are:
o IPv4 header options
o IPv6 hop-by-hop options
o Fields in non-unicast packets (anycast, multicast, broadcast)
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5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
ICMPv6, UDP, and TCP Headers", RFC 4727,
DOI 10.17487/RFC4727, November 2006,
<https://www.rfc-editor.org/info/rfc4727>.
5.2. Informational References
[RFC2637] Hamzeh, K., Pall, G., Verthein, W., Taarud, J., Little,
W., and G. Zorn, "Point-to-Point Tunneling Protocol
(PPTP)", RFC 2637, DOI 10.17487/RFC2637, July 1999,
<https://www.rfc-editor.org/info/rfc2637>.
Author's Address
Martin D. J. Rosenau
Email: martin@rosenau-ka.de
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