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IETF RFC 9837
Last modified on Saturday, August 23rd, 2025
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Internet Engineering Task Force (IETF) R. Bonica
Request for Comments: 9837 Juniper Networks
Category: Experimental X. Li
ISSN: 2070-1721 CERNET Center/Tsinghua University
A. Farrel
Old Dog Consulting
Y. Kamite
NTT DOCOMO BUSINESS
L. Jalil
Verizon
August 2025
The IPv6 VPN Service Destination Option
 Abstract
This document describes an experiment in which VPN service
information is encoded in an experimental IPv6 Destination Option.
The experimental IPv6 Destination Option is called the VPN Service
Option.
One purpose of this experiment is to demonstrate that the VPN Service
Option can be deployed in a production network. Another purpose is
to demonstrate that the security measures described in this document
are sufficient to protect a VPN. Finally, this document encourages
replication of the experiment.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation.
This document defines an Experimental Protocol for the Internet
community. This document is a product of the Internet Engineering
Task Force (IETF). It represents the consensus of the IETF
community. It has received public review and has been approved for
publication by the Internet Engineering Steering Group (IESG). Not
all documents approved by the IESG are candidates for any level of
Internet Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/RFC 9837.
Copyright Notice
Copyright (c) 2025 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.
Table of Contents
1. Introduction
2. Conventions and Definitions
3. The VPN Service Option
4. Forwarding Plane Considerations
5. Control Plane Considerations
6. IANA Considerations
7. Security Considerations
8. Deployment Considerations
9. Experimental Results
10. References
10.1. Normative References
10.2. Informative References
Acknowledgements
Authors' Addresses
1. Introduction
Generic Packet Tunneling [RFC 2473] allows a router in one network to
encapsulate a packet in an IP header and send it to a router in
another network. The receiving router removes the outer IP header
and forwards the original packet into its own network. This
facilitates connectivity between networks that share a private
addressing [RFC 1918] [RFC 4193] plan but are not connected by a direct
link.
The IETF refined this concept in the Framework for VPN [RFC 2764].
The IETF also standardized the following VPN technologies:
* IPsec VPN [RFC 3884]
* Layer 3 VPN (L3VPN) [RFC 4364]
* Virtual Private LAN Service (VPLS) [RFC 4761][RFC 4762]
* Layer 2 VPN (L2VPN) [RFC 6624]
* Ethernet VPN (EVPN) [RFC 7432]
* Pseudowires [RFC 8077]
* Segment Routing over IPv6 (SRv6) [RFC 8986]
* EVPN / Network Virtualization over Layer 3 (NVO3) [RFC 9469]
IPsec VPNs cryptographically protect all traffic from customer
endpoint to customer endpoint. All of the other VPN technologies
mentioned above share the following characteristics:
* An ingress Provider Edge (PE) router encapsulates customer data in
a tunnel header. The tunnel header includes service information.
Service information identifies a Forwarding Information Base (FIB)
entry on an egress PE router.
* The ingress PE router sends the encapsulated packet to the egress
PE router.
* The egress PE router receives the encapsulated packet.
* The egress PE router searches its FIB for an entry that matches
the incoming service information. If it finds one, it removes the
tunnel header and forwards the customer data to a Customer Edge
(CE) device, as per the FIB entry. If it does not find a matching
FIB entry, it discards the packet.
This document describes an experiment in which VPN service
information is encoded in an experimental IPv6 Destination Option
[RFC 8200]. The experimental IPv6 Destination Option is called the
VPN Service Option.
The solution described in this document offers the following
benefits:
* It does not require configuration on CE devices.
* It encodes service information in the IPv6 extension header.
Therefore, it does not require any non-IPv6 headers (e.g., MPLS
headers) to carry service information.
* It supports many VPNs on a single egress PE router.
* When a single egress PE router supports many VPNs, it does not
require an IP address per VPN.
* It does not rely on any particular control plane.
One purpose of this experiment is to demonstrate that the VPN Service
Option can be deployed in a production network. Another purpose is
to demonstrate that the security measures described in Section 7 of
this document are sufficient to protect a VPN. Finally, this
document encourages replication of the experiment, so that
operational issues can be discovered.
2. Conventions and Definitions
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 [RFC 2119] [RFC 8174] when, and only when, they appear in all
capitals, as shown here.
3. The VPN Service Option
The VPN Service Option is an IPv6 Destination Option encoded
according to rules defined in [RFC 8200].
As described in Section 4.2 of [RFC 8200], an IPv6 Destination Option
contains three fields: Option Type, Opt Data Len, and Option Data.
In the VPN Service Option, these fields are used as follows:
* Option Type: 8-bit selector. VPN Service Option. This field MUST
be set to 0x5E (RFC 3692-style Experiment) [V6MSG]. See NOTE
below.
* Opt Data Len: 8-bit unsigned integer. Length of the option, in
bytes, excluding the Option Type and Option Length fields. This
field MUST be set to 4.
* Option Data: 32 bits. VPN service information that identifies a
FIB entry on the egress PE. The FIB entry determines how the
egress PE will forward customer data to a CE device.
A single VPN Service Option MAY appear in a Destination Options
header that immediately precedes an upper-layer header. It MUST NOT
appear in any other extension header. If a receiver finds the VPN
Service Option in any other extension header, it MUST NOT recognize
the option. The packet MUST be processed according to the setting of
the two highest-order bits of the Option Type (see NOTE below).
NOTE: For this experiment, the Option Type is set to '01011110',
i.e., 0x5E. The highest-order two bits are set to 01, indicating
that the required action by a destination node that does not
recognize the option is to discard the packet. The third highest-
order bit is set to 0, indicating that Option Data cannot be modified
along the path between the packet's source and its destination. The
remaining low-order bits are set to '11110' to indicate the single
IPv6 Destination Option Type code point available in the "Destination
Options and Hop-by-Hop Options" registry [V6MSG] for experimentation.
4. Forwarding Plane Considerations
The ingress PE encapsulates the customer data in a tunnel header.
The tunnel header MUST contain an IPv6 header and a Destination
Options header that immediately precedes the customer data. It MAY
also include any legal combination of IPv6 extension headers.
The IPv6 Header contains the following (all defined in [RFC 8200]):
* Version - MUST be equal to 6.
* Traffic Class
* Flow Label
* Payload Length
* Next Header
* Hop Limit
* Source Address - Represents an interface on the ingress PE router.
This address SHOULD be chosen according to guidance provided in
[RFC 6724].
* Destination Address - Represents an interface on the egress PE
router. This address SHOULD be chosen according to guidance
provided in [RFC 6724].
The IPv6 Destination Options Extension Header contains the following
(all defined in [RFC 8200]):
* Next Header - MUST identify the protocol of the customer data.
* Hdr Ext Len
* Options - In this experiment, the Options field MUST contain
exactly one VPN Service Option as defined in Section 3 of this
document. It MAY also contain any legal combination of other
Destination Options.
5. Control Plane Considerations
The FIB can be populated by:
* An operator, using a Command-Line Interface (CLI)
* A controller, using the Path Computation Element Communication
Protocol (PCEP) [RFC 5440] or the Network Configuration Protocol
(NETCONF) [RFC 6241]
* A routing protocol
Routing protocol extensions that support the VPN Service Option are
beyond the scope of this document.
6. IANA Considerations
This document has no IANA actions.
7. Security Considerations
A VPN is characterized by the following security policy:
* Nodes outside of a VPN cannot inject traffic into the VPN.
* Nodes inside a VPN cannot send traffic outside of the VPN.
A set of PE routers cooperate to enforce this security policy. If a
device outside of that set could impersonate a device inside of the
set, it would be possible for that device to subvert security policy.
Therefore, impersonation must not be possible. The following
paragraphs describe procedures that prevent impersonation.
The VPN Service Option can be deployed:
* On the global Internet
* Inside of a limited domain
When the VPN Service Option is deployed on the global Internet, the
tunnel that connects the ingress PE to the egress PE MUST be
cryptographically protected by one of the following:
* The IPv6 Authentication Header (AH) [RFC 4302]
* The IPv6 Encapsulating Security Payload (ESP) Header [RFC 4303]
When the VPN Service Option is deployed in a limited domain, all
nodes at the edge of limited domain MUST maintain Access Control
Lists (ACLs). These ACLs MUST discard packets that satisfy the
following criteria:
* Contain a VPN Service Option
* Contain an IPv6 Destination Address that represents an interface
inside of the limited domain
The mitigation techniques mentioned above operate in fail-open mode.
That is, they require explicit configuration in order to ensure that
packets using the approach described in this document do not leak out
of a domain. See [SAFE-LIM-DOMAINS] for a discussion of fail-open
and fail-closed modes.
For further information on the security concerns related to IP
tunnels and the recommended mitigation techniques, please see
[RFC 6169].
8. Deployment Considerations
The VPN Service Option is imposed by an ingress PE and processed by
an egress PE. It is not processed by any other nodes along the
delivery path between the ingress PE and egress PE.
However, some networks discard packets that include IPv6 Destination
Options. This is an impediment to deployment.
Because the VPN Service Option uses an experimental code point, there
is a risk of collisions with other experiments. Specifically, the
egress PE may process packets from another experiment that uses the
same code point.
As with all experiments with IETF protocols, it is expected that care
is taken by the operator to ensure that all nodes participating in an
experiment are carefully configured.
Because the VPN Service Destination Option uses an experimental code
point, processing of this option MUST be disabled by default.
Explicit configuration is required to enable processing of the
option.
9. Experimental Results
Parties participating in this experiment should publish experimental
results within one year of the publication of this document.
Experimental results should address the following:
* Effort required to deploy
- Was deployment incremental or network-wide?
- Was there a need to synchronize configurations at each node, or
could nodes be configured independently?
- Did the deployment require a hardware upgrade?
* Effort required to secure
- Performance impact
- Effectiveness of risk mitigation with ACLs
- Cost of risk mitigation with ACLs
* Mechanism used to populate the FIB
* Scale of deployment
* Interoperability
- Did you deploy two interoperable implementations?
- Did you experience interoperability problems?
* Effectiveness and sufficiency of Operations, Administration, and
Maintenance (OAM) mechanisms
- Did PING work?
- Did TRACEROUTE work?
- Did Wireshark work?
- Did TCPDUMP work?
10. References
10.1. Normative References
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC 2119, March 1997,
<https://www.rfc-editor.org/info/RFC 2119>.
[RFC 6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security
Concerns with IP Tunneling", RFC 6169,
DOI 10.17487/RFC 6169, April 2011,
<https://www.rfc-editor.org/info/RFC 6169>.
[RFC 6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC 6724, September 2012,
<https://www.rfc-editor.org/info/RFC 6724>.
[RFC 8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC 8174,
May 2017, <https://www.rfc-editor.org/info/RFC 8174>.
[RFC 8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC 8200, July 2017,
<https://www.rfc-editor.org/info/RFC 8200>.
10.2. Informative References
[RFC 1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.
J., and E. Lear, "Address Allocation for Private
Internets", BCP 5, RFC 1918, DOI 10.17487/RFC 1918,
February 1996, <https://www.rfc-editor.org/info/RFC 1918>.
[RFC 2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, DOI 10.17487/RFC 2473,
December 1998, <https://www.rfc-editor.org/info/RFC 2473>.
[RFC 2764] Gleeson, B., Lin, A., Heinanen, J., Armitage, G., and A.
Malis, "A Framework for IP Based Virtual Private
Networks", RFC 2764, DOI 10.17487/RFC 2764, February 2000,
<https://www.rfc-editor.org/info/RFC 2764>.
[RFC 3884] Touch, J., Eggert, L., and Y. Wang, "Use of IPsec
Transport Mode for Dynamic Routing", RFC 3884,
DOI 10.17487/RFC 3884, September 2004,
<https://www.rfc-editor.org/info/RFC 3884>.
[RFC 4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, DOI 10.17487/RFC 4193, October 2005,
<https://www.rfc-editor.org/info/RFC 4193>.
[RFC 4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC 4302, December 2005,
<https://www.rfc-editor.org/info/RFC 4302>.
[RFC 4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC 4303, December 2005,
<https://www.rfc-editor.org/info/RFC 4303>.
[RFC 4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC 4364, February
2006, <https://www.rfc-editor.org/info/RFC 4364>.
[RFC 4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, DOI 10.17487/RFC 4761, January 2007,
<https://www.rfc-editor.org/info/RFC 4761>.
[RFC 4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC 4762, January 2007,
<https://www.rfc-editor.org/info/RFC 4762>.
[RFC 5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC 5440, March 2009,
<https://www.rfc-editor.org/info/RFC 5440>.
[RFC 6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC 6241, June 2011,
<https://www.rfc-editor.org/info/RFC 6241>.
[RFC 6624] Kompella, K., Kothari, B., and R. Cherukuri, "Layer 2
Virtual Private Networks Using BGP for Auto-Discovery and
Signaling", RFC 6624, DOI 10.17487/RFC 6624, May 2012,
<https://www.rfc-editor.org/info/RFC 6624>.
[RFC 7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC 7432, February
2015, <https://www.rfc-editor.org/info/RFC 7432>.
[RFC 8077] Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and
Maintenance Using the Label Distribution Protocol (LDP)",
STD 84, RFC 8077, DOI 10.17487/RFC 8077, February 2017,
<https://www.rfc-editor.org/info/RFC 8077>.
[RFC 8986] 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/RFC 8986, February 2021,
<https://www.rfc-editor.org/info/RFC 8986>.
[RFC 9469] Rabadan, J., Ed., Bocci, M., Boutros, S., and A. Sajassi,
"Applicability of Ethernet Virtual Private Network (EVPN)
to Network Virtualization over Layer 3 (NVO3) Networks",
RFC 9469, DOI 10.17487/RFC 9469, September 2023,
<https://www.rfc-editor.org/info/RFC 9469>.
[SAFE-LIM-DOMAINS]
Kumari, W., Alston, A., Vyncke, É., Krishnan, S., and D.
Eastlake, "Safe(r) Limited Domains", Work in Progress,
Internet-Draft, draft-wkumari-intarea-safe-limited-
domains-04, 3 March 2025,
<https://datatracker.ietf.org/doc/html/draft-wkumari-
intarea-safe-limited-domains-04>.
[V6MSG] IANA, "Destination Options and Hop-by-Hop Options",
<https://www.iana.org/assignments/ipv6-parameters>.
Acknowledgements
Thanks to Gorry Fairhurst, Antoine Fressancourt, Eliot Lear, and Mark
Smith for their reviews and contributions to this document.
Authors' Addresses
Ron Bonica
Juniper Networks
Herndon, Virginia
United States of America
Email: rbonica@juniper.net
Xing Li
CERNET Center/Tsinghua University
Beijing
China
Email: xing@cernet.edu.cn
Adrian Farrel
Old Dog Consulting
United Kingdom
Email: adrian@olddog.co.uk
Yuji Kamite
NTT DOCOMO BUSINESS
Chiyoda-ku, Tokyo
Japan
Email: y.kamite@ntt.com
Luay Jalil
Verizon
Richardson, Texas
United States of America
Email: luay.jalil@one.verizon.com
RFC TOTAL SIZE: 20925 bytes
PUBLICATION DATE: Saturday, August 23rd, 2025
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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