6man R. Bonica
Internet-Draft Juniper Networks
Intended status: Standards Track Y. Kamite
Expires: August 6, 2021 NTT Communications Corporation
L. Jalil
Verizon
Y. Zhou
ByteDance
G. Chen
Baidu
February 2, 2021
The IPv6 Tunnel Payload Forwarding (TPF) Option
draft-bonica-6man-vpn-dest-opt-15
Abstract
This document explains how IPv6 options can be used in IPv6 tunnels.
It also defines the IPv6 Tunnel Payload Forwarding (TPF) option.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. The IPv6 Tunnel Payload Forwarding (TPF) Option . . . . . . . 4
4. TPF Information Determines Next-Protocol Engine Behavior . . 5
5. TPF Information Semantics . . . . . . . . . . . . . . . . . . 5
6. Virtual Private Networking (VPN) Applications . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
This document explains how IPv6 options [RFC8200] can be used in IPv6
tunnels. It also defines the IPv6 Tunnel Payload Forwarding (TPF)
option.
An IPv6 tunnel [RFC2473] connects two nodes, called the entry-point
and the exit-point. The entry-point receives a packet and
encapsulates it in a Tunnel IPv6 Header. Figure 1 depicts the
encapsulation.
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+----------------------------------//-----+
| Original | |
| | Original Packet Payload |
| Header | |
+----------------------------------//-----+
< Original Packet >
|
v
<Tunnel IPv6 Headers> < Original Packet >
+---------+ - - - - - +-------------------------//--------------+
| IPv6 | IPv6 | |
| | Extension | Original Packet |
| Header | Headers | |
+---------+ - - - - - +-------------------------//--------------+
< Tunnel IPv6 Packet >
Figure 1: IPv6 Tunnel Encapsulation
The original packet can be any layer-2 or layer-3 packet (e.g.,
Ethernet, IPv4, IPv6). The Tunnel Header is an IPv6 header followed
by zero or more extension headers. The resulting packet is a Tunnel
IPv6 Packet.
The entry-point sends the Tunnel IPv6 Packet to the exit-point which
then executes the following procedure:
o Process the Tunnel IPv6 Header.
o Remove the Tunnel IPv6 Header, exposing the original packet.
o Submit the original packet to the next-protocol engine.
The exit-point node processes the Tunnel IPv6 Header in strict left-
to-right order. It processes the IPv6 header first and then
processes extension headers in the order that they appear in the
packet. The IPv6 header, and each extension header, includes a Next
Header field. The last Next Header field processed identifies the
next-protocol engine.
Entry-point nodes can send optional information to the next-protocol
engine on the exit-point node. For example, the entry-point can
indicate:
o The interface through which the next-protocol engine should send
the packet.
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o The routing table that the next-protocol engine should use to
process the packet.
To send this information, the entry-point node includes an IPv6
Destination Option header in the Tunnel IPv6 Header. The IPv6
Destination Options header includes an IPv6 TPF option and the IPv6
TPF option includes TPF information. The next-protocol engine on the
exit-point node uses TPF information when it forwards the original
packet.
2. 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. The IPv6 Tunnel Payload Forwarding (TPF) Option
The TPF Option contains the following fields:
o Option Type: 8-bit selector. TPF option. Value TBD by IANA.
(Suggested value: 0x41). See Note below.
o Opt Data Len - 8-bit unsigned integer. Length of the option, in
octets, excluding the Option Type and Option Length fields. This
field MUST be set to 4.
o Option Data - 32-bits. Tunnel Payload Forwarding (TPF)
Information.
The TPF option MAY appear in a Destination Options header that
precedes an upper-layer header. It MUST NOT appear in a Hop-by-hop
Options header or in a Destination Options header that precedes a
Routing header.
NOTE : The highest-order two bits of the Option Type (i.e., the "act"
bits) are 01. These bits specify the action taken by a destination
node that does not recognize the option. The required action is to
discard the packet. The third highest-order bit of the Option Type
(i.e., the "chg" bit) is 0. This indicates that Option Data cannot
be modified along the path between the packet's source and its
destination.
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4. TPF Information Determines Next-Protocol Engine Behavior
An exit-point node supports one or more next-protocol engines (e.g.,
Ethernet, IPv4, IPv6). Each next-protocol engine supports a default
forwarding procedure and zero or more special forwarding procedures.
When an exit-point node submits a packet to a next-protocol engine
without TPF information, the next-protocol engine executes its
default forwarding procedure. For example, assume that the exit-
point node receives the following Tunnel IPv6 Packet:
o The Tunnel IPv6 Packet does not contain TPF information.
o The original packet is IPv4.
In this case, the exit-point node processes and removes the Tunnel
IPv6 Header. It then submits the original packet, without any TPF
information, to the IPv4 protocol engine.
The IPv4 protocol engine executes its default forwarding procedure.
It searches its Forwarding Information Base (FIB) for and entry that
matches the original packet's destination address. If the search
returns a FIB entry, the protocol engine forwards the packet through
an interface that the FIB entry identifies.
When an exit-point node submits a packet to a next-protocol engine
with TPF information, the next-protocol engine executes a special
forwarding procedure. For example, assume that the exit-point node
receives the following Tunnel IPv6 packet:
o The Tunnel IPv6 Packet contains TPF information that identifies an
interface.
o The original packet is IPv4.
In this case, the exit-point node processes and removes the Tunnel
IPv6 Header. It then submits the original packet, along with TPF
information, to the IPv4 protocol engine.
The IPv4 protocol engine executes a special forwarding procedure. It
forwards the packet through the interface identified by TPF
information, without searching the FIB.
5. TPF Information Semantics
TPF information is opaque. While it must be understood by the entry-
point node and the exit-point node, it does not need to be understood
by any other node.
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6. Virtual Private Networking (VPN) Applications
The IPv6 TPF option is useful in deployments where IPv6 tunnels
carry:
o Layer 3 Virtual Private Network (L3VPN) [RFC4364] traffic.
o Ethernet Virtual Private Network (EVPN) [RFC7432] traffic.
When an IPv6 tunnel carries L3VPN traffic, VPN context information
can be encoded in an IPv6 TPF option. Therefore, the MPLS service
label that is normally present in an L3VPN packet can be eliminated.
When an IPv6 tunnel carries EVPN traffic, VPN context information can
be encoded in an IPv6 TPF option. Therefore, the UDP and VXLAN
headers that might otherwise be present can be eliminated.
7. Security Considerations
TPF information MUST NOT be accepted from untrusted sources. The
following are acceptable methods of risk mitigation:
o Authenticate the IPv6 TPF option using the IPv6 Authentication
Header (AH) [RFC4302] or the IPv6 Encapsulating Security Payload
(ESP) Header [RFC4303].
o Maintain a secure TPF domain.
All nodes at the edge of a secure TPF domain discard packets that
satisfy the following criteria:
o Contain an IPv6 TPF option.
o Contain an IPv6 Destination Address that represents an interface
inside of the secure TPF domain.
8. IANA Considerations
IANA is requested to allocate a code point 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
"Tunnel Payload Forwarding Option". The "act" bits are 01 and the
"chg" bit is 0. The suggested value is 0x41.
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9. Acknowledgements
Thanks to Dr. Vanessa Ameen, Brian Carpenter, Adrian Farrel, Ishaan
Gandhi, Tom Herbert, John Leddy, Srihari Sangli and Tony Li for their
comments.
10. Contributors
Chris Lenart
Verizon
22001 Loudoun County Parkway
Ashburn, Virginia 20147 USA
Email: chris.lenart@verizon.com
Greg Presbury
Hughes Network Systems
11717 Exploration Lane
Germantown, Maryland 20876 USA
Email: greg.presbury@hughes.com
11. References
11.1. 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>.
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
December 1998, <https://www.rfc-editor.org/info/rfc2473>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC4302, December 2005,
<https://www.rfc-editor.org/info/rfc4302>.
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[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/info/rfc4303>.
[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>.
11.2. Informative References
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC7432] 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/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
Authors' Addresses
Ron Bonica
Juniper Networks
2251 Corporate Park Drive
Herndon, Virginia 20171
USA
Email: rbonica@juniper.net
Yuji Kamite
NTT Communications Corporation
3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
Email: y.kamite@ntt.com
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Luay Jalil
Verizon
Richardson, Texas
USA
Email: luay.jalil@one.verizon.com
Yifeng Zhou
ByteDance
Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian
District
Beijing 100000
P.R. China
Email: yifeng.zhou@bytedance.com
Gang Chen
Baidu
No.10 Xibeiwang East Road Haidian District
Beijing 100193
P.R. China
Email: phdgang@gmail.com
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