Internet DRAFT - draft-eastlake-dnsop-rrtype-srv6
draft-eastlake-dnsop-rrtype-srv6
DNSOP D. Eastlake
Internet-Draft H. Song
Intended status: Standards Track Futurewei Technologies
Expires: 1 April 2024 29 September 2023
The IPv6 Segment Routing (SRv6) Domain Name System (DNS) Resource Record
draft-eastlake-dnsop-rrtype-srv6-04
Abstract
A Domain Name System (DNS) Resource Record (RR) Type is specified for
storing IPv6 Segment Routing (SRv6) Information in the DNS.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
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1.1. IPv6 Segment Routing . . . . . . . . . . . . . . . . . . 2
1.2. The SRV6 RR Type . . . . . . . . . . . . . . . . . . . . 3
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. SRV6 RR Type RDATA . . . . . . . . . . . . . . . . . . . . . 4
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Normative References . . . . . . . . . . . . . . . . . . . . 5
7. Informative References . . . . . . . . . . . . . . . . . . . 6
Appendix A. SRV6 RR Type Template . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The Domain Name System (DNS) is a hierarchical, distributed, highly
available database with a variety of security features [RFC4034]
[RFC4035] used for bi-directional mapping between domain names and
addresses, for email routing, and for other information [RFC1034]
[RFC1035]. This data is formatted into resource records (RRs) whose
content type and structure are indicated by the RR Type field.
General familiarity with the DNS and its terminology [RFC8499] is
assumed in this document.
1.1. IPv6 Segment Routing
Internet Protocol versions 4 (IPv4, [RFC0791]) and 6 (IPv6,
[RFC8200]) have long provided header options that support including
an ordered sequence of addresses in a packet header so the packet
travels in order through the nodes specified by that sequence of
addresses. This is sometimes referred to as "source routing" because
the route or path the packet follows is set, at least in part, when
the sequence of addresses is added to the packet, usually at the
packet's source, rather than being dynamically determined as the
packet proceeds through the network.
IPv6 Segment Routing (SRv6, [RFC8402]) extends "source routing" by
generalizing the IPv6 sized "address" quantities in a source
"routing" sequence to be "instructions". [RFC8754] specifies a
particular Segment Routing Header (SRH) that may be use used as part
of the headers of an IPv6 packet to indicate an IPv6 Segment Routing
sequence of addresses / instructions. And [RFC8986] further
specifies the structuring of an IPv6 address size quantity such that
it may be composed of addressing information followed by a function
designation which is optionally further followed by arguments to that
function. Thus, segment routing might encode a series of operations
to be performed on a packet.
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Furthermore, because a sequence of SRv6 instructions may all start
with the same constant addressing prefix, methods of compression have
been specified [Compress] to represent this addressing prefix less
often and pack an increased number of quantities into a Segment
Routing Header where each quantity may consist optionally of
additional address information and/or function designation and/or
function arguments.
1.2. The SRV6 RR Type
This document specifies a SRV6 RR Type to return a sequence of IPv6
Segment Routing addresses / instructions and optionally other data.
In many ways, the data returned for an SRV6 DNS RR is like an
address. This RR supports a DNS client querying for SRV6 RRs at a
name, inserting returned SRv6 information into the header of an IPv6
packet, and transmitting that packet so addressed. It would also be
reasonable for an application using SRv6 to do a type SRV DNS query
[RFC2782] followed by an SRV6 query at the resulting domain name if
it was in a domain where SRv6 was in use. Furthermore, as a fall
back, if no SRV6 RR is present in the DNS at a domain name, a client
application whose SRV6 query has failed could query for the AAAA IPv6
address RR type.
Segment Routing is intended to be used in a limited domain compared
with the global Internet. Furthermore, the DNS is commonly thought
of as the source for global Internet addressing. However, most DNS
servers can be easily configured in a network so that some names are
only visible locally and some RRs are only delivered locally.
1.3. Terminology
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.
The following acronyms are used in this document:
DNS - Domain Name System
IANA - Internet Assigned Number Authority
IPv6 - Internet Protocol Version 6 [RFC8200]
RR - DNS Resource Record
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SID - Segment Identifier [RFC8402]
SRH - Segment Routing (IPv6) Header [RFC8754]
SRv6 - IPv6 Segment Routing [RFC8402]
SRV6 - Mnemonic for the SRv6 RR Type
TLV - Type, Length, Value
2. SRV6 RR Type RDATA
The SRV6 RR type enables the storage and retrieval of an ordered
sequence of SRv6 quantities each of which is the size of an IPv6
[RFC8200] address. The RDATA for this type of RR is a set of fields
followed by a sequence of such quantities followed by optional data
(see Figure 1) and will be ( 4 + N*16 + Opt) bytes long, where N is
the number of such quantities present and Opt is the length of the
optional data.
The RR Type Code for the SRV6 RR is TBD1.
0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID Count | SRH Flags | SRH Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| 16-byte SRv6 Address/Instruction (SID) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. Additional 16-byte SRv6 Addresses/Instructions (SIDs) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Optional TLVs .
.................................................................
Figure 1: SRV6 RRTYPE Data
The RDATA consists of a segment count followed by a flags byte, a 2
byte tag, and then one or more 128-bit SRv6 SIDs followed by optional
TLV data, all as further detailed as follows:
SID Count - As unsigned one byte integer giving the number of
16-byte SRv6 SIDs in the RDATA.
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SRH Flags - This byte gives a initial value for the Flags field of
the Segment Routing Header (SRH, [RFC8754]).
SRH Tag - This field is a suggested value for the Tag field of the
SRH [RFC8754].
SIDs - 16-byte SRv6 segment identifiers (SIDs, [RFC8402].
Optional TLVs - Suggested TLVs for inclusion in a Segment Routing
Header (SRH, [RFC8754]) created using this RDATA.
If the RDATA length is less than (4 + (SID Count)*16) or if the
Optional TLVs do not parse as SRH TLVs, then the RR is malformed and
MUST be ignored.
Circumstances and/or future definition of flags and TLV types may
require, when an IPv6 packet header is contructed based on an SRV6
RR, that some SRH FLags be set or clear regardless of the SRH Flags
RR field and/or that some SRH TLVs be included or excluded regardless
of the Optional TLV in the SRH RR.
3. Acknowledgements
The suggestions and comments of the following persons are gratefully
acknowledged:
tbd
4. IANA Considerations
IANA is requested to assign an SRV6 RR Type (TBD1) as in the template
in Appendix A.
5. Security Considerations
For information on DNS features that improve the authentication of
retrieved RRs, see [RFC4034] and [RFC4035].
For SRv6 Security Considerations, see [RFC8402] and Section 5 of
[RFC8754]. For Security Considerations of SRv6 Network Programming,
see [RFC8986]
6. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
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[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[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>.
[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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
7. Informative References
[Compress] Cheng, W., Ed., Filsfils, C., Ed., Previdi, S., Li, Z.,
Decraene, B., and F. Clad, "Compressed SRv6 Segment List
Encoding in SRH", 13 September 2023,
<https://datatracker.ietf.org/doc/draft-ietf-spring-srv6-
srh-compression/>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782,
DOI 10.17487/RFC2782, February 2000,
<https://www.rfc-editor.org/info/rfc2782>.
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[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record
(RR) Types", RFC 3597, DOI 10.17487/RFC3597, September
2003, <https://www.rfc-editor.org/info/rfc3597>.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<https://www.rfc-editor.org/info/rfc4034>.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<https://www.rfc-editor.org/info/rfc4035>.
[RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
Appendix A. SRV6 RR Type Template
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A. Submission Date: tbd
B.1 Submission Type: [X] New RRTYPE [ ] Modification to RRTYPE
B.2 Kind of RR: [X] Data RR [ ] Meta-RR
C. Contact Information for submitter (will be publicly posted):
Name: Donald Eastlake
Email Address: d3e3e3@gmail.com
International telephone number: +1-508-333-2270
Other contact handles:
D. Motivation for the new RRTYPE application.
Enable storeage of IPv6 Segment Routing sequences in the DNS.
E. Description of the proposed RR type.
See draft-eastlake-dnsop-rrtype-srv6
F. What existing RRTYPE or RRTYPEs come closest to filling that need
and why are they unsatisfactory?
Perhaps AAAA but that only returns a single IPv6 address, not an
ordered sequence of IPv6 sized SRv6 instructions.
G. What mnemonic is requested for the new RRTYPE (optional)?
SRV6
H. Does the requested RRTYPE make use of any existing IANA registry
or require the creation of a new IANA subregistry in DNS
Parameters? If so, please indicate which registry is to be used
or created. If a new subregistry is needed, specify the
allocation policy for it and its initial contents.
Does not use any existing registry and does not create a new
registry.
I. Does the proposal require/expect any changes in DNS
servers/resolvers that prevent the new type from being processed
as an unknown RRTYPE (see [RFC3597])?
No.
J. Comments: None.
Authors' Addresses
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Donald Eastlake
Futurewei Technologies
2386 Panoramic Circle
Apopka, FL 32703
United States of America
Phone: +1 508 333 2270
Email: d3e3e3@gmail.com
Haoyu Song
Futurewei Technologies
2220 Central Expressway
Santa Clara, CA 95050
United States of America
Email: haoyu.song@futurewei.com
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