Internet DRAFT - draft-ls-6man-ipcomp-exclude-transport-layer
draft-ls-6man-ipcomp-exclude-transport-layer
IPv6 Maintenance C. Li
Internet-Draft H. Shi, Ed.
Intended status: Standards Track M. Zhang
Expires: 8 May 2024 X. Ding
Huawei Technologies
5 November 2023
IP Payload Compression excluding transport layer
draft-ls-6man-ipcomp-exclude-transport-layer-02
Abstract
IP Payload Compression Protocol (IPComp) is used for compressing the
IP payload in transmission to increase communication performance.
The IPComp is applied to the payload of the IP datagram, starting
with the first octet immediately after the IP header in IPv4, and the
first octet after the excluded IPv6 Extension headers. However,
transport layer information such as source port and destination port
are useful in many network functions in transmission.
This document defines extensions of IP payload compression protocol
(IPComp) to support compressing the payload excluding the transport
layer information, to enable network functions using transport layer
information (e.g., ECMP) working together with the payload
compression. This document also defines an extension of IPComp to
indicate the payload is not compressed to solve the out-of-order
problems between the compressed and uncompressed packets.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://VMatrix1900.github.io/ipcomp-exclude-transport-layer/draft-
ls-6man-ipcomp-exclude-transport-layer.html. Status information for
this document may be found at https://datatracker.ietf.org/doc/draft-
ls-6man-ipcomp-exclude-transport-layer/.
Discussion of this document takes place on the IPv6 Maintenance
Working Group mailing list (mailto:ipv6@ietf.org), which is archived
at https://mailarchive.ietf.org/arch/browse/ipv6/. Subscribe at
https://www.ietf.org/mailman/listinfo/ipv6/.
Source for this draft and an issue tracker can be found at
https://github.com/VMatrix1900/ipcomp-exclude-transport-layer.
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Status of This Memo
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This Internet-Draft will expire on 8 May 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
4. Extensions to IPComp . . . . . . . . . . . . . . . . . . . . 4
4.1. Four-bytes Exclusion Extension . . . . . . . . . . . . . 4
4.2. Uncompressed Payload Extension . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
The IP Payload Compression Protocol (IPComp) [RFC3173] is defined to
compress the IP payload in transmission in order to increase the
communication performance between a pair of communicating nodes,
provided the nodes have sufficient computation power and the
communication is over slow or congested links.
In IP version 4, the compression is applied to the payload of the IP
datagram, starting at the first octet following the IP header, and
continuing through the last octet of the datagram. In the IPv6
context, IPComp is viewed as an end-to-end payload, and is not
applied to IPv6 extension headers such as hop-by-hop, routing, and
fragmentation extension headers[RFC8200]. The compression is applied
starting at the first IP Header Option field that does not carry
information that must be examined and processed by nodes along a
packet's delivery path, if such an IP Header Option field exists, and
continues to the ULP payload of the IP datagram. Therefore, the
transport layer information such as source port and destination port
is compressed. When IPComp is used, the Next Header field of IP
header is set to 108, IPComp Datagram. The IPComp header contains
the original Next Header and the Compress Parameter Index(CPI) is
inserted between the IP header and the compressed payload.
There are many network functions which needs the transport layer
information to work. For example, flow-based ECMP, Carrier Grade
Network Translation (CGNAT), Access Control List (ACL) may require
source and destination port to identify the transport layer flow.
Some Firewall (FW), Deep Packet Inspection (DPI) also need to inspect
the transport layer information. If IPComp compressed those
transport layer information, the nodes along the packet's delivery
path can not obtain the source port and destination port. Therefore
the IPComp is not compatible with the network functions requiring the
transport layer information which makes it harder to deploy.
This document defines an extension of IPComp to support compressing
the payload excluding the first 4 bytes of transport layer header
which contains source port and destination port. In this way, the
IPComp can coexist with many network functions which requires these
information. This document also defines an extension to explicitly
indicate the payload is uncompressed to solve the out-of-order
processing between the compressed and uncompressed packets.
2. Terminology
This document leverages the terms defined in [RFC3173]. The reader
is assumed to be familiar with this terminology.
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2.1. Requirements Language
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. Problem Statement
Currently, the IPComp will compress all the IP payload which includes
the transport layer information. If a layer 4 load balancer is
deployed along the IPComp packet delivery path, then the load
balancer can not obtain the source port and destination port to
identify a flow without decompressing it first. In other words, the
network functions which requires the transport layer information
would also need to act as the decompression node of IPComp. This
incompatibility makes the deployment of IPComp harder.
4. Extensions to IPComp
This section defines two extensions of IPComp. The first extension
is used to indicate the first four bytes of transport layer header
which contains the source port and destination is excluded from the
compression. The second extension indicates that the payload is not
compressed.
4.1. Four-bytes Exclusion Extension
This extension is used to indicate that the first four bytes of the
transport layer header is excluded from the compression. The packet
format using this extension is shown in Figure 1(Demonstrated using
IPv6 packet):
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Flags | Compression Parameter Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Destination Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// Compressed Payload //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Packet format when using Four-bytes Exclusion Extension
To accomplish that there are two options to extend IPComp. The first
option is to change the CPI field. Currently the CPI field
identifies a particular compression algorithm. The defined CPI value
can be found at [CPI-IANA]. We can define new CPI values to indicate
the same compression algorithm with different compression range as
shown in Table 1.
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+=======+==========================================+===============+
| Value | Transform ID | References |
+=======+==========================================+===============+
| 0 | RESERVED | [RFC2407] |
+-------+------------------------------------------+---------------+
| 1 | IPCOMP_OUI | [RFC2407] |
+-------+------------------------------------------+---------------+
| 2 | IPCOMP_DEFLATE | [RFC2407] |
+-------+------------------------------------------+---------------+
| 3 | IPCOMP_LZS | [RFC2407] |
+-------+------------------------------------------+---------------+
| 4 | IPCOMP_LZJH | [RFC3051] |
+-------+------------------------------------------+---------------+
| TBD | IPCOMP_OUI with four bytes exclusion | This document |
+-------+------------------------------------------+---------------+
| TBD | IPCOMP_DEFLATE with four bytes exclusion | This document |
+-------+------------------------------------------+---------------+
| TBD | IPCOMP_LZS with four bytes exclusion | This document |
+-------+------------------------------------------+---------------+
| TBD | IPCOMP_LZJH with four bytes exclusion | This document |
+-------+------------------------------------------+---------------+
Table 1: CPI with exclusion range Registry Entries
The second option is to change the Flags field. Currently, the Flags
field is zero and ignored by the receiving node. We can introduce a
bit to indicate whether the first four bytes is excluded from the
compression range or not.
Which option is more suitable will be determined based on the
discussion in the working group.
4.2. Uncompressed Payload Extension
Currently, if the total size of a compressed payload and the IPComp
header is not smaller than the size of the original payload, the IP
datagram will be sent in the original non-compressed form without the
IPComp header. In the receiving node, the packet with the IPComp
header will go through the decompression co-processor first while the
packet without the IPComp header will be forwarded directly. Going
through different packet process path will cause the out-of-order of
packets within the same flow, reducing the transport performance.
To solve the out-of-order packets within the same IPComp-enabled
flow, we propose to add IPComp header no matter whether the packet
within the IPComp-enabled flow is sent compressed or not. To
indicate a packet is sent uncompressed, a new CPI value(TBD) is used.
In this way, since all packets within the IPComp-enabled flow have
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IPComp header, they will go through the same process path and be
processed in order. For uncompressed packet, the Next Header in the
IPComp Header is copied into the Next Header in the IP header, and
the IPComp Header is removed.
5. IANA Considerations
TBD.
6. Security Considerations
The security requirements and mechanisms described in [RFC3173] also
apply to this document.
This document does not introduce any new security considerations.
7. References
7.1. 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/rfc/rfc2119>.
[RFC2407] Piper, D., "The Internet IP Security Domain of
Interpretation for ISAKMP", RFC 2407,
DOI 10.17487/RFC2407, November 1998,
<https://www.rfc-editor.org/rfc/rfc2407>.
[RFC3051] Heath, J. and J. Border, "IP Payload Compression Using
ITU-T V.44 Packet Method", RFC 3051, DOI 10.17487/RFC3051,
January 2001, <https://www.rfc-editor.org/rfc/rfc3051>.
[RFC3173] Shacham, A., Monsour, B., Pereira, R., and M. Thomas, "IP
Payload Compression Protocol (IPComp)", RFC 3173,
DOI 10.17487/RFC3173, September 2001,
<https://www.rfc-editor.org/rfc/rfc3173>.
[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/rfc/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/rfc/rfc8200>.
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7.2. Informative References
[CPI-IANA] "IPSEC IPCOMP Transform Identifiers", October 2022,
<https://www.iana.org/assignments/isakmp-registry/isakmp-
registry.xhtml#isakmp-registry-11>.
Authors' Addresses
Cheng Li
Huawei Technologies
China
Email: c.l@huawei.com
Hang Shi (editor)
Huawei Technologies
China
Email: shihang9@huawei.com
Meng Zhang
Huawei Technologies
China
Email: zhangmeng6@huawei.com
Xiaobo Ding
Huawei Technologies
China
Email: mirroryuri.ding@huawei.com
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