Framework for End-to-End IETF
Network SlicingHuawei TechnologiesHuawei Campus, No. 156 Beiqing RoadBeijing100095Chinalizhenbin@huawei.comHuawei TechnologiesHuawei Campus, No. 156 Beiqing RoadBeijing100095Chinajie.dong@huawei.comNetwork 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.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.The definition and the characteristics of IETF network slice are
introduced in , and describes a
general framework of IETF network slice. 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 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. 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.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:Local VTN-ID: This is the VTN-ID as defined in . 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.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.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.This section lists the requirements on E2E IETF network slicing.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.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.This document makes no request of IANA.Note to RFC Editor: this section may be removed on publication as an
RFC.TBDTBDFramework for IETF Network SlicesEricssonJuniper Networks