Network Working Group J. Dong
Internet-Draft Z. Li
Intended status: Standards Track Huawei Technologies
Expires: January 13, 2022 C. Xie
C. Ma
China Telecom
G. Mishra
Verizon Inc.
July 12, 2021
Carrying Virtual Transport Network Identifier in IPv6 Extension Header
draft-dong-6man-enhanced-vpn-vtn-id-04
Abstract
A Virtual Transport Network (VTN) is a virtual network which has a
customized network topology and a set of dedicated or shared network
resources allocated from the physical network. A VTN can be used as
the underlay for one or a group of overlay VPNs to provide enhanced
VPN (VPN+) services. In packet forwarding, some fields in the data
packet needs to be used to identify the VTN the packet belongs to, so
that the VTN-specific processing can be performed on each node the
packet traverses.
This document proposes a new Hop-by-Hop option of IPv6 extension
header to carry the VTN ID, which can be used to identify the Virtual
Transport Network (VTN) the packet belongs to. The procedure for
processing the VTN option is also specified.
Status of This Memo
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This Internet-Draft will expire on January 13, 2022.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. New IPv6 Extension Header Option for VTN . . . . . . . . . . 3
3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. VTN Option Insertion . . . . . . . . . . . . . . . . . . 4
3.2. VTN based Packet Forwarding . . . . . . . . . . . . . . . 5
4. Operational Considerations . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Virtual Private Networks (VPNs) provide different customers with
logically isolated connectivity over a common network infrastructure.
With the introduction and evolvement of 5G, some existing or new
services may require connectivity services with advanced
characteristics comparing to traditional VPNs, such as resource
isolation from other services or guaranteed performance. These
services are refered to as "enhanced VPNs" (VPN+).
[I-D.ietf-teas-enhanced-vpn] describes a framework and the candidate
component technologies for providing VPN+ services.
The enhanced properties of VPN+ require tighter coordination and
integration between the underlay and the overlay network. VPN+
service can be delivered using a Virtual Transport Network (VTN) as
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the underlay, which has a customized network topology and a set of
dedicated or shared network resources allocated from the physical
network. The overlay VPN together with the corresponding VTN in the
underlay constitute the VPN+ service. In the network, traffic of
different VPN+ services need to be processed separately based on the
topology and the network resources associated with the corresponding
VTN.
[I-D.dong-teas-enhanced-vpn-vtn-scalability] describes the
scalability considerations and the possible optimizations for
providing a relatively large number of VTNs for VPN+ services, one
approach to improve the data plane scalability is by introducing a
dedicated VTN Identifier (VTN ID) in the data packet to identify the
VTN the packet belongs to, so that VTN-specific packet processing can
be performed on each node the packet traverses. This is called
Resource Independent (RI) VTN.
This document proposes a mechanism to carry the VTN ID in a new Hop-
by-Hop option of IPv6 extension header [RFC8200] of IPv6 packet, so
that on each network node along the packet forwarding path, the VTN
option in the packet is parsed, and the obtained VTN-ID instructs the
network node to use the network resources allocated to the
corresponding VTN to process and forward the packet. The procedure
for processing the VTN ID is also specified. This provides a
scalable solution to support a relatively large number of VTNs in an
IPv6 network.
1.1. 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
BCP14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
2. New IPv6 Extension Header Option for VTN
A new Hop-by-Hop option type "VTN" is defined to carry the Virtual
Transport Network Identifier (VTN ID) in an IPv6 packet. Its format
is shown as below:
Option Option Option
Type Data Len Data
+--------+--------+------------------+
|BBCTTTTT|00000100| 4-octet VTN ID |
+--------+--------+------------------+
Figure 1. The format of VTN Option
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Option Type: 8-bit identifier of the type of option. The type of VTN
option is to be assigned by IANA. The highest-order bits of the type
field are defined as below:
o BB 00 The highest-order 2 bits are set to 00 to indicate that a
node which does not recognize this type will skip over it and
continue processing the header.
o C 0 The third highest-order bit are set to 0 to indicate this
option does not change en route.
Opt Data Len: 8-bit unsigned integer indicates the length of the
option Data field of this option, in octets. The value of Opt Data
Len of VTN option SHOULD be set to 4.
VTN-ID: 4-octet identifier which uniquely identifies a VTN.
Editor's note: The length of the VTN ID is defined as 4-octet in
correspondence to the 4-octet Single Network Slice Selection
Assistance Information (S-NSSAI) defined in 3GPP [TS23501].
8-bit 24-bit
+------------+-------------------------+
| SST | Slice Differentiator |
+------------+-------------------------+
Figure 2. The format of S-NSSAI
3. Procedures
As the VTN option needs to be processed by each node along the path
for VTN-specific forwarding, it SHOULD be carried in IPv6 Hop-by-Hop
options header when the Hop-by-Hop options header can be either
processed or ignored in forwarding plane by all the nodes along the
path.
3.1. VTN Option Insertion
When an ingress node of an IPv6 domain receives a packet, according
to the traffic classification or mapping policy, the packet is
steered into one of the VTNs in the network, then the packet SHOULD
be encapsulated in an outer IPv6 header, and the identifier of the
VTN which the packet is mapped to SHOULD be carried in the VTN option
of the Hop-by-Hop options header associated with the outer IPv6
header.
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3.2. VTN based Packet Forwarding
On receipt of a packet with the VTN option, each network node which
can process the VTN option in fast path SHOULD use the VTN-ID to
identify the VTN the packet belongs to, so that the set of local
network resources allocated to the VTN could be determined. The
packet forwarding behavior is based on both the destination IP
address and the VTN-ID. More specifically, the destination IP
address is used to determine the next-hop and the outgoing interface,
and VTN-ID is used to determine the set of network resources reserved
for processing and sending the packet on the outgoing interface. The
Traffic Class field of the outer IPv6 header MAY be used to provide
Diffserv treatment for packets which belong to the same VTN. The
egress node of the IPv6 domain SHOULD decapsulate the outer IPv6
header which includes the VTN option.
In the forwarding plane, there can be different instantiations of
local network resources allocated to the VTNs. For example, on one
interface, a subset of forwarding plane resources (e.g. the bandwidth
and the associated buffer and queuing resources) allocated to a
particular VTN can be represented as a virtual sub-interface with
dedicated bandwidth resources. In packet forwarding, the IPv6
destination address of the received packet is used to identify the
next-hop and the outgoing interface, and the VTN-ID is used to
further identify the virtual sub-interface which is associated with
the VTN on the outgoing interface.
Routers which do not support the processing of Hop-by-Hop options
header SHOULD ignore the Hop-by-Hop options header and forward the
packet only based on the destination IP address. Routers which
support Hop-by-Hop Options header, but do not support the VTN option
SHOULD ignore the VTN-ID option and continue to forward the packet
based on the destination IP address and MAY also based on the rest of
the Hop-by-Hop Options.
4. Operational Considerations
As described in [RFC8200], nodes may be configured to ignore the Hop-
by-Hop Options header, and in some implementations a packet
containing a Hop-by-Hop Options header may be dropped or assigned to
a slow processing path. The proposed modification to the processing
of IPv6 Hop-by-Hop options header is specified in
[I-D.hinden-6man-hbh-processing]. Operator needs to make sure that
all the network nodes involved in a VTN can either process Hop-by-Hop
Options header in the fast path, or ignore the Hop-by-Hop Option
header. In other word, packets steered into a VTN MUST NOT be
dropped due to the existence of the Hop-by-Hop Options header. It is
RECOMMENDED to configure all the nodes involved in a VTN to process
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the Hop-by-Hop Options header and the VTN option if there is a nob
for this.
5. IANA Considerations
This document requests IANA to assign a new option type from
"Destination Options and Hop-by-Hop Options" registry.
Value Description Reference
--------------------------------------
TBD VTN Option this document
6. Security Considerations
The security considerations with IPv6 Hop-by-Hop options header are
described in [RFC8200], [RFC7045] and
[I-D.hinden-6man-hbh-processing]. This document introduces a new
IPv6 Hop-by-Hop option which is either processed in the fast path or
ignored by network nodes, thus it does not introduce additional
security issues.
7. Contributors
Zhibo Hu
Email: huzhibo@huawei.com
Lei Bao
Email: baolei7@huawei.com
8. Acknowledgements
The authors would like to thank Juhua Xu and James Guichard for their
review and valuable comments.
9. References
9.1. 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>.
[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>.
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[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>.
9.2. Informative References
[I-D.dong-teas-enhanced-vpn-vtn-scalability]
Dong, J., Li, Z., Qin, F., Yang, G., and J. N. Guichard,
"Scalability Considerations for Enhanced VPN (VPN+)",
draft-dong-teas-enhanced-vpn-vtn-scalability-02 (work in
progress), February 2021.
[I-D.hinden-6man-hbh-processing]
Hinden, R. M. and G. Fairhurst, "IPv6 Hop-by-Hop Options
Processing Procedures", draft-hinden-6man-hbh-
processing-00 (work in progress), December 2020.
[I-D.ietf-teas-enhanced-vpn]
Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
Framework for Enhanced Virtual Private Network (VPN+)
Services", draft-ietf-teas-enhanced-vpn-07 (work in
progress), February 2021.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC 7045,
DOI 10.17487/RFC7045, December 2013,
<https://www.rfc-editor.org/info/rfc7045>.
[TS23501] "3GPP TS23.501", 2016,
<https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=3144>.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing 100095
China
Email: jie.dong@huawei.com
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Zhenbin Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing 100095
China
Email: lizhenbin@huawei.com
Chongfeng Xie
China Telecom
China Telecom Beijing Information Science & Technology, Beiqijia
Beijing 102209
China
Email: xiechf@chinatelecom.cn
Chenhao Ma
China Telecom
China Telecom Beijing Information Science & Technology, Beiqijia
Beijing 102209
China
Email: machh@chinatelecom.cn
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
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