6man R. Bonica
Internet-Draft Juniper Networks
Intended status: Standards Track J. Halpern
Expires: September 10, 2019 Ericsson
X. Xu
Alibaba Inc
G. Chen
Baidu
Y. Zhu
G. Yang
China Telecom
March 9, 2019
The IPv6 Segment Endpoint Option
draft-bonica-6man-seg-end-opt-02
Abstract
This document defines the IPv6 Segment Endpoint Option. Source nodes
can use this option to convey internet-layer information to selected
segment endpoints along a packet's delivery path.
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 September 10, 2019.
Copyright Notice
Copyright (c) 2019 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
4. Option Format . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Option Processing . . . . . . . . . . . . . . . . . . . . . . 5
6. Mutability . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
IPv6 [RFC8200] options convey optional internet-layer information to
selected nodes along a packets delivery path. IPv6 options can be
encoded as follows:
o In a Hop-by-hop Options header.
o In a Destination Options header that precedes a Routing header.
o In a Destination Options header that precedes an upper-layer
header.
If an option is encoded in a Hop-by-hop Options header, it conveys
information to every node along the packet's delivery path, including
the destination node. (See NOTE 1). If an option is encoded in a
Destination Options header that precedes a Routing header, it conveys
information to every segment endpoint along the packet's delivery
path, including the destination node. If an option is encoded in a
Destination Options header that precedes an upper-layer header, it
conveys information to the destination node only. (See Section 4.3.4
of [RFC8200] )
This document defines the IPv6 Segment Endpoint option. The IPv6
Segment Endpoint option provides a mechanism through which a source
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node can convey optional internet-layer information to selected
segment endpoints. For example, assume that a packet's delivery path
contains three segments. The source node can use the Segment
Endpoint option to convey one piece of information to the first
segment endpoint, another piece if information to the second segment
endpoint, and no information to the third segment endpoint.
NOTE 1: As per IPv6 [RFC8200], it is now expected that nodes along a
packet's delivery path only examine and process the Hop-by-Hop
Options header if explicitly configured to do so.
2. Terminology
o Segment Endpoint - A packet that contains a Routing header
traverses multiple segments. Each segment has an endpoint. The
first destination that appears in the IPv6 Destination Address
identifies the first segment endpoint. Subsequent destinations
listed in the Routing header identify subsequent segment
endpoints. A packet that does not contain a Routing Header
traverses exactly one segment had has exactly one segment endpoint
(i.e., the packet's ultimate destination).
3. 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.
4. Option Format
The Segment Endpoint option MAY appear in a Destination Options
header, regardless of whether that Destination Options header
precedes a Routing header or an upper-layer header. The Segment
Endpoint option MUST NOT appear in a Hop-by-hop Options header.
Figure 1 depicts the Segment Endpoint option.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 1: Segment Endpoint Option
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o Option Type - Segment Endpoint option. Value TBD by IANA. See
NOTE 1 and NOTE 2, below.
o Opt Data Len - 8-bit unsigned integer. Length of the Option Data
field, in octets.
o Option Data - See Figure 2.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segments Left | Containers | Container List
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 2: Option Data
Option Data contains the following fields:
o Segments Left - 8-bit unsigned integer. Number of route segments
remaining. If the packet also contains a Routing header, this
value MUST be identical to the value of the Segments Left field in
the Routing heder. See Section 5.
o Containers - 8-bit unsigned integer. The number of containers in
the Container List.
o Container List - A list of Containers (Figure 3).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment ID | IPv6 Option
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 3: A Container
Each element of Container List contains the following fields:
o Segment ID - 8-bit unsigned integer. Identifies the segment that
should process the IPv6 Option contained by this container. See
Section 5.
o IPv6 Option - Any IPv6 Option [IPv6-OPT] except for the Segment
Endpoint Option.
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Within a Container list, Containers MUST be sorted in descending
order by Segment ID.
NOTE 1: The highest-order two bits of the Option Type (i.e., the
"act" bits) are 10. These bits specify the action taken by a
destination node that does not recognize Segment Endpoint option.
The required action is to discard the packet and send an ICMPv6
[RFC4443] Parameter Problem, Code 2, message to the packet's Source
Address, pointing to the Segment Endpoint option Type.
NOTE 2: The third highest-order bit of the Option Type (i.e., the
"chg" bit) is 1. This indicates that Option Data can be modified
along the path between the packet's source and its destination.
5. Option Processing
If the option appears in a Hop-by-hop Options header, the processing
node discards the packet and sends an ICMPv6 [RFC4443] Parameter
Problem, Code 2, message to the packet's Source Address, pointing to
the Segment Endpoint option Type.
If the option appears in a Destination Options header, the processing
node locates the following fields in Option Data:
o Segments Left.
o Containers.
o Container List.
It then processes each member of the Container List as follows:
o Locate the Segment ID and IPv6 Option field in the container.
o If Segments Left less than the Segment ID, skip over the
container.
o If Segments Left equals the Segment ID, and the IPv6 Option is a
Segment Endpoint option, skip over the container.
o If Segments Left equals the Segment ID, and the IPv6 Option is not
a Segment Endpoint option, process the IPv6 Option as per
[RFC8200].
o If Segments Left is greater than Segment ID, skip over all
remaining members of the Container List.
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Finally, decrement the Segment ID field and process the next option
or header.
6. Mutability
The Segments Left field of the Segment Endpoint option is mutable.
Intermediate nodes MAY change the value of this field.
All other fields in the Segment Endpoint option are immutable.
Intermediate nodes MUST NOT change the values of these fields.
7. Security Considerations
The Segment Endpoint Option shares many security concerns with IPv6
routing headers. In particular, any boundary filtering protecting a
domain from external routing headers should also protect against
external Segment Endpoint Options being processed inside a domain.
This occurs naturally if encapsulation is used to add routing headers
to a packet. If external routing headers are allowed, then
protections must also include ensuring that any provided Segment
Endpoint option before the routing header is properly protect, e.g.
with an IPSEC AH header or other suitable means.
As with Routing headers, the security assumption within a domain is
that the domain is trusted to provide, and to avoid improperly
modifying, the Segment Endpoint Option.
8. IANA Considerations
IANA is requested to allocate a codepoint from the Destination
Options and Hop-by-hop Options registry
(https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtml#ipv6-parameters-2). This option is called
"Segment Endpoint". The "act" bits are 10 and the "chg" bit is 1.
9. Acknowledgements
Thanks to TBD for their careful review of this document.
10. References
10.1. 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>.
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[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[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>.
10.2. Informative References
[IPv6-OPT]
IANA, ""Destination Options and Hop-by-Hop Options"",
August 1987, <https://www.iana.org/assignments/ipv6-
parameters/ipv6-parameters.xhtml#ipv6-parameters-2>.
Authors' Addresses
Ron Bonica
Juniper Networks
2251 Corporate Park Drive
Herndon, Virginia 20171
USA
Email: rbonica@juniper.net
Joel Halpern
Ericsson
P. O. Box 6049
Leesburg, Virginia 20178
USA
Email: joel.halpern@ericsson.com
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Xiaohu Xu
Alibaba Inc
Alibaba Park
Hangzhou
P.R. China
Email: xiaohu.xxh@alibaba-inc.com
Gang Chen
Baidu
Baidu Technology Park Building No.2, No.10 Xibeiwang East Road Haidian District
Beijing 100193
P.R. China
Email: phdgang@gmail.com
Yongqing Zhu
China Telecom
109 West Zhongshan Ave, Tianhe District
Guangzhou
P.R. China
Email: zhuyq.gd@chinatelecom.cn
Guangming Yang
China Telecom
109 West Zhongshan Ave, Tianhe District
Guangzhou
P.R. China
Email: yanggm.gd@chinatelecom.cn
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