Internet DRAFT - draft-dong-6man-enhanced-vpn-vtn-id
draft-dong-6man-enhanced-vpn-vtn-id
Network Working Group J. Dong
Internet-Draft Z. Li
Intended status: Standards Track Huawei Technologies
Expires: April 27, 2022 C. Xie
C. Ma
China Telecom
G. Mishra
Verizon Inc.
October 24, 2021
Carrying Virtual Transport Network (VTN) Identifier in IPv6 Extension
Header
draft-dong-6man-enhanced-vpn-vtn-id-06
Abstract
Virtual Private Networks (VPNs) provide different customers with
logically separated connectivity over a common network
infrastructure. With the introduction and evolvement of 5G and other
network scenarios, some existing or new customers may require
connectivity services with advanced characteristics comparing to
traditional VPNs. Such kind of network service is called enhanced
VPNs (VPN+).
A Virtual Transport Network (VTN) is a virtual underlay network which
consists of a set of dedicated or shared network resources allocated
from the physical underlay network, and is associated with a
customized logical network topology. VPN+ services can be delivered
by mapping one or a group of overlay VPNs to the appropriate VTNs as
the virtual underlay. 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 Resource ID, which is used to identify the
set of network resources allocated to a VTN for packet processing.
The procedure for processing the VTN option is also specified.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on April 27, 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. New IPv6 Extension Header Option for VTN . . . . . . . . . . 4
3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. VTN Option Insertion . . . . . . . . . . . . . . . . . . 5
3.2. VTN based Packet Forwarding . . . . . . . . . . . . . . . 5
4. Operational Considerations . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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 and other network
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scenarios, some existing or new customers may require connectivity
services with advanced characteristics comparing to traditional VPNs,
such as resource isolation from other services or guaranteed
performance. Such kind of network service is called enhanced VPN
(VPN+). VPN+ service requires the coordination and integration
between the overlay VPNs and the network characteristics of the
underlay.
[I-D.ietf-teas-enhanced-vpn] describes a framework and the candidate
component technologies for providing VPN+ services. It also
introduces the concept of Virtual Transport Network (VTN). A Virtual
Transport Network (VTN) is a virtual underlay network which consists
of a set of dedicated or shared network resources allocated from the
physical underlay network, and is associated with a customized
logical network topology. VPN+ services can be delivered by mapping
one or a group of overlay VPNs to the appropriate VTNs as the
underlay, so as to provide the network characteristics required by
the customers. In packet forwarding, traffic of different VPN+
services need to be processed separately based on the network
resources and the logical topology 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 of VTN is to introduce
a dedicated VTN Resource Identifier (VTN Resource ID) in the data
packet to identify the set of network resources allocated to a VTN,
so that VTN-specific packet processing can be performed using that
set of resources, which avoids the possible resource competition with
services in other VTNs. This is called Resource Independent (RI)
VTN. A VTN Resource ID represents a subset of the resources (e.g.
bandwidth, buffer and queuing resources) allocated on a given set of
links and nodes which constitute a logical network topology. The
logical topology associated with a VTN could be defined using
mechanisms such as Multi-Topology [RFC4915], [RFC5120] or Flex-Algo
[I-D.ietf-lsr-flex-algo], etc.
This document proposes a mechanism to carry the VTN resource 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
Resource ID is used to instruct the network node to use the set of
network resources allocated to the corresponding VTN to process and
forward the packet. The procedure for processing the VTN Resource ID
is also specified. This provides a scalable solution to support a
relatively large number of VTNs in an IPv6 network.
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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 VTN
related Identifier in an IPv6 packet. Its format is shown as below:
Option Option Option
Type Data Len Data
+--------+--------+-------------------------+
|BBCTTTTT|00000100| 4-octet VTN Resource ID |
+--------+--------+-------------------------+
Figure 1. The format of VTN Option
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 Resource ID: 4-octet identifier which uniquely identifies the set
of network resources allocated to a VTN.
Editor's note: The length of the VTN Resource 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
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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 Resource ID 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.
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 Resource
ID to determine the set of local network resources allocated to the
VTN for packet processing. The packet forwarding behavior is based
on both the destination IP address and the VTN Resource ID. More
specifically, the destination IP address is used to determine the
next-hop and the outgoing interface, and VTN Resource ID is used to
determine the set of network resources on the outgoing interface
which are reserved to the VTN for processing and sending the packet.
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 approaches of
partitioning the local network resources and allocating them to
different VTNs. For example, on one physical interface, a subset of
the forwarding plane resources (e.g. the bandwidth and the associated
buffer and queuing resources) can be allocated to a particular VTN
and represented as a virtual sub-interface with reserved bandwidth
resource. In packet forwarding, the IPv6 destination address of the
received packet is used to identify the next-hop and the outgoing
layer-3 interface, and the VTN Resource ID is used to further
identify the virtual sub-interface which is associated with the VTN
on the outgoing interface.
Network nodes which do not support the processing of Hop-by-Hop
options header SHOULD ignore the Hop-by-Hop options header and
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forward the packet only based on the destination IP address. Network
nodes which support Hop-by-Hop Options header, but do not support the
VTN option SHOULD ignore the VTN 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], network 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. Since a VTN is associated with a logical network topology,
it is practical to ensure that all the network nodes involved in that
logical topology support the processing of the HBH options header and
the VTN option. 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 network nodes involved in a VTN
to process 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
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Zhibo Hu
Email: huzhibo@huawei.com
Lei Bao
Email: baolei7@huawei.com
8. Acknowledgements
The authors would like to thank Juhua Xu, James Guichard, Joel
Halpern and Tom Petch for their review and valuable comments.
9. References
9.1. Normative References
[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-08 (work in
progress), July 2021.
[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>.
9.2. Informative References
[I-D.dong-teas-enhanced-vpn-vtn-scalability]
Dong, J., Li, Z., Gong, L., Yang, G., Guichard, J. N.,
Mishra, G., and F. Qin, "Scalability Considerations for
Enhanced VPN (VPN+)", draft-dong-teas-enhanced-vpn-vtn-
scalability-03 (work in progress), July 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-01 (work in progress), June 2021.
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[I-D.ietf-lsr-flex-algo]
Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
algo-17 (work in progress), July 2021.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007,
<https://www.rfc-editor.org/info/rfc4915>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>.
[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
Zhenbin Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing 100095
China
Email: lizhenbin@huawei.com
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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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