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. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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. Rosenau Expires June 24, 2018 [Page 1] Internet-Draft PrenegotiatedOptions December 2017 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as 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: Rosenau Expires June 24, 2018 [Page 2] Internet-Draft PrenegotiatedOptions December 2017 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 Rosenau Expires June 24, 2018 [Page 3] Internet-Draft PrenegotiatedOptions December 2017 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) Rosenau Expires June 24, 2018 [Page 4] Internet-Draft PrenegotiatedOptions December 2017 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, . [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP Headers", RFC 4727, DOI 10.17487/RFC4727, November 2006, . 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, . Author's Address Martin D. J. Rosenau Email: martin@rosenau-ka.de Rosenau Expires June 24, 2018 [Page 5]