IPv4 Parcels and Advanced Jumbos (AJs)
draft-templin-intarea-parcels-93
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Author | Fred Templin | ||
| Last updated | 2023-12-14 (Latest revision 2023-12-13) | ||
| Replaced by | draft-templin-intarea-parcels2 | ||
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draft-templin-intarea-parcels-93
Network Working Group F. L. Templin, Ed.
Internet-Draft Boeing Research & Technology
Intended status: Standards Track 14 December 2023
Expires: 16 June 2024
IPv4 Parcels and Advanced Jumbos (AJs)
draft-templin-intarea-parcels-93
Abstract
IPv6 Parcels and Advanced Jumbos (AJs) present new data packaging
constructs and a new link model for Internetworking. As is often the
case, technologies developed in the IPv6 space can also be applied in
IPv4 and vice-versa. This document presents the adaptations
necessary to support Parcels and AJs in IPv4.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 16 June 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 2
3. IPv4 Parcels and Advanced Jumbos (AJs) . . . . . . . . . . . 3
3.1. IPv4 Total Length . . . . . . . . . . . . . . . . . . . . 3
3.2. IPv4 Time To Live (TTL) . . . . . . . . . . . . . . . . . 3
3.3. IPv4 Parcel/Jumbo Payload Length . . . . . . . . . . . . 4
3.4. IPv4-Compatible IPv6 Addresses . . . . . . . . . . . . . 4
3.5. IPv4 Parcel Packetization/Restoration . . . . . . . . . . 4
3.6. Parcel/Jumbo Replys and MTU Reports . . . . . . . . . . . 4
3.7. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Implementation Status . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
IPv6 Parcels and Advanced Jumbos (AJs) [I-D.templin-6man-parcels]
present new data packaging constructs and a new link model for
Internetworking. As is often the case, technologies developed in the
IPv6 space [RFC8200] can also be applied in IPv4 [RFC0791] and vice-
versa. This document presents the differences that need to be
addressed to adapt IPv6 Parcels and AJs to IPv4.
All aspects of IPv6 Parcels and AJs, including the use of IPv6
extension headers and control messaging, apply also to IPv4. Only
differences in the IP header format and some control option
encapsulations need to be accounted for as discussed below. This
document therefore specifies IPv4 parcels and AJs.
2. Requirements
IPv4 parcels and AJs observe all requirements established for IPv6
[I-D.templin-6man-parcels] including the use of IPv6 Hop-by-Hop
Options headers. This means that nodes that recognize IPv4 parcels/
AJs MUST recognize and correctly process IP protocol 0 (Hop-by-Hop)
option headers the same as for IPv6 when they occur in an extension
header chain following the IPv4 header but before the upper layer
payload.
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When an IPv4 router or destination end system processes a parcel or
AJ for which the IPv4 Protocol field encodes an unrecognized value
(such as 0 for Hop-by-Hop Options), it drops the parcel/AJ and
returns an ICMPv4 "Destination Unreachable - Protocol Unreachable"
message [RFC0792]. The source then regards any such messages as an
advisory indication that parcels/AJs may not be supported along this
path.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. IPv4 Parcels and Advanced Jumbos (AJs)
All aspects of [I-D.templin-6man-parcels] are imported as normative
specifications for IPv4 parcels and AJs, with the exception of the
following differences:
3.1. IPv4 Total Length
The IPv6 header includes a "Payload Length" field defined as the:
"Length of the IPv6 payload, i.e., the rest of the packet following
this IPv6 header, in octets". The IPv4 header instead includes a
"Total Length" field defined as: "the length of the datagram,
measured in octets, including internet header and data".
These differences have no bearing for parcels/AJs, for which both the
IPv6 Payload Length and IPv4 Total Length values carry identical
codes. The same as for IPv6, IPv4 parcels encode the length "L" of
the first segment in Total Length, while IPv4 AJs encode a jumbo type
value in Total Length.
3.2. IPv4 Time To Live (TTL)
The IPv4 "Time To Live (TTL)" and IPv6 "Hop Limit" values are treated
in exactly the same way in both protocol versions. In particular,
the source sets the TTL/Hop Limit to an initial value and each router
in the path to the destination decrements the TTL/Hop Limit by 1 when
it forwards the parcel/AJ.
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3.3. IPv4 Parcel/Jumbo Payload Length
The same as for IPv6, the Parcel Payload Length field in the Parcel
Payload Option and the Jumbo Payload Length field in the Jumbo
Payload Option of IPv4 parcels/AJs encode the length of the IPv6
extension headers plus the length of the {TCP,UDP} header plus the
combined length of all concatenated segments with their per-segment
headers/trailers.
Therefore, the length of the IPv4 header itself is not included in
the Parcel/Jumbo Payload Length field the same as for IPv6. The IPv4
header length for IPv4 parcels and AJs is instead calculated from the
IPv4 header Internet Header Length (IHL) field the same as for
ordinary IPv4 packets.
3.4. IPv4-Compatible IPv6 Addresses
Whenever an IPv4 address needs to be coded in an IPv6 address field,
the address is coded as an IPv4-compatible IPv6 address as specified
in [RFC4291].
3.5. IPv4 Parcel Packetization/Restoration
When a node performs packetization on a {TCP,UDP}/IPv4 parcel, it
inserts a Parcel Segment {TCP,UDP} option the same as for IPv6
[I-D.templin-6man-parcels].
The IPv4 destination then performs restoration by gathering up IPv4
packets that arrive with the same upper layer 5-tuple and with Parcel
Segment information including the same Identification. The Parcel
Segment Index then determines the ordinal position of each packet
segment to be concatenated into the restoration buffer, i.e., the
same as for IPv6. (Note: if the IPv4 destination does not recognize
the {TCP,UDP} Parcel Segment option, it simply processes the packet
as a singleton IPv4 packet. This would result in correct behavior,
but would fail to take advantage of Generic Receive Offload (GRO)
benefits.)
3.6. Parcel/Jumbo Replys and MTU Reports
When an IPv4 router receives an intact Parcel/Jumbo probe, it can
return an immediate Parcel/Jumbo Reply if necessary in an ICMPv6
Packet Too Big (PTB) message prepared the same as for IPv6 but
wrapped in UDP/IPv4 encapsulation headers. The Reply will then
traverse the IPv4 network on the reverse path to the source.
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When an IPv4 destination receives a Parcel/Jumbo probe, it should
instead return an MTU/Fragmentation Report option in any
{TCP,UDP}/IPv4 packet to be returned to the source the same as for
IPv6 [I-D.templin-6man-parcels].
When the IPv4 source receives a {TCP,UDP} packet that includes an
MTU/Fragmentation Report it matches the Identification value with one
its recently-transmitted probes. If there is a match, the source
then marks the destination as "Parcels/Jumbos supported" and records
the MTU value found in the pseudo-option as the path MTU.
3.7. Integrity
To support the IPv4 parcel/AJ header checksum calculation, the
network layer uses modified versions of the {TCP,UDP}/IPv4 pseudo-
header found in [RFC9293]. Note that while the contents of the two
IP protocol version-specific pseudo-headers beyond the address fields
are the same, the order in which the contents are arranged differs
and must be honored according to the specific IP protocol version.
The IPv6 pseudo-header is found in [I-D.templin-6man-parcels], while
the IPv4 pseudo-header is shown in Figure 1. The similarities
between the two pseudo-headers allows for maximal reuse of widely
deployed code while ensuring interoperability.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Source Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Destination Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| zero | Next Header | Segment Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Index |P|S| Parcel Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: {TCP,UDP}/IPv4 Parcel/AJ Pseudo-Header Format
Note: The same as for IPv6, the Index/P/S and Parcel Payload Length
fields in the IPv4 parcel pseudo-header are replaced by the single
4-octet Jumbo Payload Length field in the IPv4 AJ pseudo-header.
4. Implementation Status
An early prototype of UDP/IPv4 parcels (draft version -15) has been
implemented relative to the linux-5.10.67 kernel and ION-DTN ion-
open-source-4.1.0 source distributions. Patch distribution found at:
"https://github.com/fltemplin/ip-parcels.git".
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5. IANA Considerations
This document does not include any IANA instructions.
6. Security Considerations
Security Considerations are the same as for IPv6 as found in
[I-D.templin-6man-parcels].
7. Acknowledgements
This work was inspired by ongoing AERO/OMNI/DTN investigations. The
concepts were further motivated through discussions with colleagues.
Honoring life, liberty and the pursuit of happiness.
8. References
8.1. Normative References
[I-D.templin-6man-parcels]
Templin, F., "IPv6 Parcels and Advanced Jumbos (AJs)",
Work in Progress, Internet-Draft, draft-templin-6man-
parcels-00, 12 December 2023,
<https://datatracker.ietf.org/doc/html/draft-templin-6man-
parcels-00>.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981,
<https://www.rfc-editor.org/info/rfc792>.
[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>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC9293] Eddy, W., Ed., "Transmission Control Protocol (TCP)",
STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022,
<https://www.rfc-editor.org/info/rfc9293>.
8.2. Informative References
Appendix A. Change Log
<< RFC Editor - remove prior to publication >>
Changes from earlier versions:
* Submit for review.
Author's Address
Fred L. Templin (editor)
Boeing Research & Technology
P.O. Box 3707
Seattle, WA 98124
United States of America
Email: fltemplin@acm.org
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