Network Working Group Z. Li
Internet-Draft J. Dong
Intended status: Standards Track Huawei Technologies
Expires: October 16, 2021 April 14, 2021
Framework for End-to-End IETF Network Slicing
draft-li-teas-e2e-ietf-network-slicing-00
Abstract
Network slicing can be used to meet the connectivity and performance
requirement of different services or customers in a shared network.
An IETF network slice may span multiple network domains. In the
context of 5G, the 5G end-to-end network slices consist of three
major types of network segments: Radio Access Network (RAN),
Transport Network (TN) and Core Network (CN).
In order to facilitate the mapping between network slices in
different network segments and network domains, it is beneficial to
carry the identifiers of the 5G end-to-end network slice, the multi-
domain IETF network slice together with the intra-domain network
slice identifier in the data packet.
This document describes the framework of end-to-end IETF network
slicing, and introduces the identifiers for 5G end-to-end network
slice and the multi-domain IETF network slice in the data packet.
The roles of the different identifiers in packet forwarding is also
described. The network slice identifiers can be instantiated with
different data planes.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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This Internet-Draft will expire on October 16, 2021.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Framework . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements on E2E IETF Network Slicing . . . . . . . . . . 5
3.1. Data Plane . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Management Plane/Control Plane . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The definition and the characteristics of IETF network slice are
introduced in [I-D.ietf-teas-ietf-network-slice-definition], and
[I-D.ietf-teas-ietf-network-slice-framework] describes a general
framework of IETF network slice.
[I-D.ietf-teas-enhanced-vpn] describes the framework and the
candidate component technologies for providing enhanced VPN services,
by utilizing an approach that is based on existing VPN and Traffic
Engineering (TE) technologies and adds characteristics that specific
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services require above traditional VPNs. VPN+ can be built from a
VPN overlay and an underlying Virtual Transport Network (VTN) which
has a customized network topology and a set of dedicated or shared
resources in the underlay network. Enhanced VPN (VPN+) can be used
for the realization of IETF network slices.
[I-D.dong-teas-enhanced-vpn-vtn-scalability] describes the
scalability considerations in the control plane and data plane to
enable VPN+ services, and provide several suggestions to improve the
scalability of VTN. In the control plane, It proposes the approach
of decoupling the topology and resource attributes of VTN, so that
multiple VTNs may share the same topology and the result of topology
based path computation. In the data plane, it proposes to carry a
VTN-ID of a network domain in the data packet to determine the set of
resources reserved for the corresponding VTN.
An IETF network slice may span multiple network domains. Further in
the context of 5G, there can be end-to-end network slices which
consists of three major types of network segments: Radio Access
Network (RAN), Transport Network (TN) and Core Network (CN). In
order to facilitate the mapping between network slices in different
network segments and network domains, it may be beneficial to also
carry the identifiers of the 5G end-to-end network slice, the multi-
domain IETF network slice together with the intra-domain network
slice identifier in the data packet.
This document describes the scenarios of end-to-end network slicing,
and the framework of network slice mapping between different network
segments and network domains. Then multiple network slice related
identifiers are defined to covers different network scopes. These
network slice identifiers can be instantiated using different data
planes, such as MPLS and IPv6.
2. Framework
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/----\ /----\ /----\ /----\ /----\
/ \ // \\ // \\ // \\ / \
| RAN |---| TN-1 |---| TN-2 |----| TN-3 |----| Core |
\ / \\ // \\ // \\ // \ /
\----/ \----/ \----/ \----/ \----/
S-NSSAI
o--------------------------------------------------------------------o
IETF Network Slice (VPN+)
o--------------------------------------------------o
Global VTN
o===========================================o
Local VTN-1 Local VTN-2 Local VTN-3
o************o o************o o***********o
Figure 1. 5G end-to-end network slicing scenario
One typical scenario of 5G end-to-end network slicing is shown in
figure 1. The 5G end-to-end network slice is identified by the
S-NSSAI (Single Network Slice Selection Assistance Information). In
the transport network segment, the 5G network slice is mapped to an
IETF network slice, which is realized with a multi-domain VPN+
service. In the underlay network, the multi-domain VPN+ service is
supported by a multi-domain VTN (Virtual Transport Network), which is
comprised by multiple intra-domain VTNs in different domains. In
each domain, a local VTN-ID is carried in the packet to identify the
set of network resource reserved for the VTN in the corresponding
domain.
In order to concatenate multiple local VTNs into a multi-domain VTN,
the global VTN-ID can be carried in the packet, which is used by the
network domain border routers to map to the local VTN-IDs in each
domain. And in order to facilitate the network slice mapping between
RAN, Core network and transport network, the S-NSSAI may be carried
in the packet sent to the transport network, which can be used by the
transport network to map the 5G end-to-end network slice to the
corresponding IETF network slice.
According to the above end-to-end network slicing scenario, there can
be three network slice related identifiers:
o Local VTN-ID: This is the VTN-ID as defined in
[I-D.dong-teas-enhanced-vpn-vtn-scalability]. It is used by the
network nodes in a network domain to determine the set of local
network resources reserved for a VTN. It SHOULD be processed by
each hop along the path in the domain.
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o Global VTN-ID: This is the identifier which uniquely identifies a
multi-domain VTN. In each network domain, the domain edge node
maps the global VTN-ID to a local VTN-ID for packet forwarding.
o 5G end-to-end network slice ID (S-NSSAI): This is the identifier
of the 5G end-to-end network slice. When required, it can be used
by the network nodes to provide traffic monitoring at the end-to-
end network slice granularity.
For the above network slice identifiers, the local VTN-ID is
mandatory, the Global VTN-ID and the 5G S-NSSAI are optional. The
existence of the Global VTN-ID depends on whether the VTN spans
multiple network domains in the transport network. The existence of
the 5G S-NSSAI depends on whether an IETF network slice is used as
part of the 5G end-to-end network slice.
3. Requirements on E2E IETF Network Slicing
This section lists the requirements on E2E IETF network slicing.
3.1. Data Plane
To facilitate the mapping between 5G end-to-end network slice and
IETF network slice, and the mapping between multi-domain IETF network
slice and the intra-domain IETF network slice, different network
slice related identifiers (e.g. S-NSSAI, Global VTN-ID, local VTN-
ID) needs to be carried in the data packet.
3.2. Management Plane/Control Plane
For multi-domain IETF network slice, a centralized IETF network slice
controller is responsible for the allocation of the Global VTN-ID and
the Local VTN-ID, and the provisioning mapping relationship of the
Global VTN-ID and the Local VTN-IDs to the network edge nodes in
different network domains.
For 5G end-to-end network slice, the edge node of transport network
can derive the S-NSSAI from the packet sent by the RAN or Core
network, and encapsulate it an outer packet header or tunnel
information when traversing the transport network. The controller
needs to be responsible for creating the mapping relationship and
provisioning it to the edge nodes of the transport network.
4. IANA Considerations
This document makes no request of IANA.
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Note to RFC Editor: this section may be removed on publication as an
RFC.
5. Security Considerations
TBD
6. Acknowledgements
TBD
7. References
7.1. 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 Networks (VPN+)
Service", draft-ietf-teas-enhanced-vpn-06 (work in
progress), July 2020.
[I-D.ietf-teas-ietf-network-slice-definition]
Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J.
Tantsura, "Definition of IETF Network Slices", draft-ietf-
teas-ietf-network-slice-definition-00 (work in progress),
January 2021.
[I-D.ietf-teas-ietf-network-slice-framework]
Gray, E. and J. Drake, "Framework for IETF Network
Slices", March 2021, <https://tools.ietf.org/html/draft-
ietf-teas-ietf-network-slice-framework>.
[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>.
7.2. Informative References
[I-D.dong-teas-enhanced-vpn-vtn-scalability]
Dong, J., Li, Z., Qin, F., and G. Yang, "Scalability
Considerations for Enhanced VPN (VPN+)", draft-dong-teas-
enhanced-vpn-vtn-scalability-01 (work in progress),
November 2020.
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Authors' Addresses
Zhenbin Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing 100095
China
Email: lizhenbin@huawei.com
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing 100095
China
Email: jie.dong@huawei.com
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