Segment Routing based Virtual Transport Network (VTN) for Enhanced VPN
draft-dong-spring-sr-for-enhanced-vpn-12
The information below is for an old version of the document.
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| Authors | Jie Dong , Stewart Bryant , Takuya Miyasaka , Yongqing Zhu , Fengwei Qin , Zhenqiang Li , Francois Clad | ||
| Last updated | 2020-12-03 (Latest revision 2020-11-02) | ||
| Replaced by | draft-ietf-spring-sr-for-enhanced-vpn, draft-ietf-spring-sr-for-enhanced-vpn | ||
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draft-dong-spring-sr-for-enhanced-vpn-12
SPRING Working Group J. Dong
Internet-Draft Huawei Technologies
Intended status: Informational S. Bryant
Expires: June 6, 2021 Futurewei Technologies
T. Miyasaka
KDDI Corporation
Y. Zhu
China Telecom
F. Qin
Z. Li
China Mobile
F. Clad
Cisco Systems
December 3, 2020
Segment Routing based Virtual Transport Network (VTN) for Enhanced VPN
draft-dong-spring-sr-for-enhanced-vpn-12
Abstract
Segment Routing (SR) leverages the source routing paradigm. A node
steers a packet through an ordered list of instructions, called
"segments". A segment can represent topological or service based
instructions. A segment can further be associated with network
resources allocated for executing the instruction. Such a segment is
called resource-aware SID.
Resource-aware SIDs may be used to build SR paths with a set of
reserved network resources. In addition, resource-aware SIDs may be
used to build SR based virtual underlay networks, which can provide
the customized network topology and resource attributes required by
different customers and/or services. Such virtual networks are
called SR based Virtual Transport Networks (VTNs). The SR based VTNs
can be used as the underlay network to enable services with required
topology and resource characteristics. This document describes a
suggested use of resource-aware SIDs to build SR based VTNs.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 6, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Resource-Aware SIDs for VTN . . . . . . . . . . . . . . . . . 3
2.1. SR-MPLS based VTN . . . . . . . . . . . . . . . . . . . . 4
2.2. SRv6 based VTN . . . . . . . . . . . . . . . . . . . . . 4
2.3. Scalability Considerations . . . . . . . . . . . . . . . 4
3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. VTN Topology and Resource Planning . . . . . . . . . . . 5
3.2. VTN Network Resource and SID Allocation . . . . . . . . . 6
3.3. Construction of SR based VTNs . . . . . . . . . . . . . . 8
3.4. Mapping Service to SR based VTN . . . . . . . . . . . . . 9
3.5. VTN Visibility to Customer . . . . . . . . . . . . . . . 10
4. Characteristics of SR based VTN . . . . . . . . . . . . . . . 10
5. Service Assurance of VTN . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
Segment Routing (SR) [RFC8402] specifies a mechanism to steer packets
through an ordered list of segments. A segment is referred to by its
Segment Identifier (SID). With SR, explicit source routing can be
achieved without introducing per-path state into the network. When
compared with RSVP-TE [RFC3209], SR currently does not have the
capability to reserve network resources or identify different sets of
network resources reserved for different customers and/or services.
[I-D.ietf-spring-resource-aware-segments] proposes to extend SR by
associating SIDs with network resource attributes, (e.g. bandwidth,
processing or storage resources). On a network segment, multiple
resource-aware SIDs may be allocated, each of which represents a
subset of network resources assigned to meet the requirements of one
or a group of customers and/or services.
Once allocated, Resource-aware SIDs can be used to build SR paths
using a set of reserved network resources. In addition, a group of
resource-aware SIDs can be used to build SR based virtual networks
with customized network topology and resource attributes. In this
document, such virtual networks are called SR based Virtual Transport
Networks (VTNs), and can be used to enable services with required
topology and resource characteristics, such as the enhanced VPN
(VPN+) services as described in [I-D.ietf-teas-enhanced-vpn].
This document describes a suggested use of resource-aware SIDs to
build SR based VTNs. Although the procedure is illustrated using SR-
MPLS, the proposed mechanism is applicable to both segment routing
over MPLS data plane (SR-MPLS) and segment routing over IPv6 data
plane (SRv6).
2. Resource-Aware SIDs for VTN
When SR is used as the data plane to provide multiple VTNs in one
network, it is necessary to compute and instantiate SR paths with the
topology constraints of the VTN, and from the set of network
resources allocated to the VTN.
With the mechanism defined in
[I-D.ietf-spring-resource-aware-segments], multiple SR SIDs can be
allocated for each network segment, with each SID used to identify
both the network topological instruction, and the set of network
resources allocated for a VTN. The mechanisms to identify the
network topology or path with a SID as defined in [RFC8402] are
reused.
The control plane mechanisms for advertising resource-aware SIDs for
different VTNs may be based on [RFC4915], [RFC5120] and
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[I-D.ietf-lsr-flex-algo] with necessary extensions. This is further
described in section 3.3.
2.1. SR-MPLS based VTN
This section describes a mechanism of allocating resource-aware SIDs
to SR-MPLS based VTNs.
For one IGP link, multiple Adj-SIDs are allocated, each of which is
associated with a VTN that link participates in, and represents a
subset of the link resources allocated to the VTN. Similarly, for
one IGP node, multiple prefix-SIDs are allocated, each of which is
associated with a VTN the node participates in, and represents a
subset of the node level processing resources allocated to the VTN.
In the case of multi-domain VTNs, on an inter-domain link, multiple
BGP peering SIDs [I-D.ietf-idr-bgpls-segment-routing-epe] are
allocated, each of which is associated with a VTN which spans
multiple domains, and represents a subset of resources allocated on
the inter-domain link.
2.2. SRv6 based VTN
This section describes a mechanism of allocating resource-aware SIDs
to VTN based on SRv6.
For a network node, multiple SRv6 Locators are allocated, each of
which is associated with a VTN that node participates in, and
represents a subset of the network resources allocated by the network
node to the VTN. The SRv6 SIDs associated with a VTN are allocated
from the SID space using the VTN-specific Locators as the prefix.
These SRv6 SIDs can be used to represent VTN-specific SRv6 functions
which are executed using the network resources allocated to the VTN.
2.3. Scalability Considerations
Note that the introduction of SR based VTNs increases the number of
SIDs and SRv6 Locators needed in a network, there may be some
concern, especially about the prefix-SIDs, which are allocated from
the Segment Routing Global Block (SRGB). The amount of network state
will also increase accordingly. However, based on the SR paradigm,
resource-aware SIDs and the associated network state are allocated
and maintained per VTN, and per-path network state is avoided in the
SR network.
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3. Procedures
This section describes possible procedures for creating SR based VTNs
and the corresponding forwarding tables and entries. Although it is
illustrated using SR-MPLS, the proposed mechanism is applicable to
both SR-MPLS and SRv6.
Suppose a virtual network is requested by some customer or service.
One of the basic requirement is that customer or service is allocated
with some dedicated network resource, so that it does not experience
unexpected interference from other services in the same network.
Other possible requirements may include the required topology,
bandwidth, latency, reliability, etc.
According to the received service requirement, a centralized network
controller calculates a subset of the underlay network topology to
support the service. Within this topology, the set of network
resources required on each network element is also determined. The
subset of network topology and network resources together constitute
a VTN. Depending on the service requirement, the network topology
and resource can be dedicated for an individual customer or service,
or can be shared by a group of customers and/or services.
Based on the mechanisms defined in
[I-D.ietf-spring-resource-aware-segments], the network topology and
resources of a VTN can be represented by a group of resource-aware
SIDs. With SR-MPLS, a group of prefix-SIDs and adj-SIDs will be used
by network nodes and the network controller to construct an SR based
VTN, which will be used as the virtual underlay network for the
requested service. Control plane protocols such as IGP (e.g. IS-IS
or OSPF) and BGP-LS can be used to distribute the SIDs and the
associated resource information of each VTN. The detailed control
plane mechanisms and possible extensions are out of the scope of this
document.
3.1. VTN Topology and Resource Planning
A centralized network controller can be responsible for the planning
of a VTN to meet the received service request. The controller needs
to collect information on network connectivity, network resources,
network performance and any other relevant network states from the
underlay network. This can be done using either IGP TE extensions
such as [RFC5305] [RFC3630] [RFC7471] [RFC8570], or BGP-LS [RFC7752]
[RFC8571], or any other form of control plane signaling.
Based on the information collected from the underlay network, the
controller obtains the underlay network topology and the information
about the allocated and available network resources. When a service
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request is received, the controller determines the subset of the
network topology, along with the set of the resources needed on each
network segment (e.g. links and nodes) in the topology to meet the
service requirements, whilst maintaining the needs of the existing
services that are using the same network. The subset of network
topology and network resources constitute a VTN, which will be used
as the virtual underlay network of the requested service.
3.2. VTN Network Resource and SID Allocation
According to the result of VTN planning, the network controller
instructs the network nodes with the information of the VTN
identifier and the required network resources to be allocated to the
VTN, so that the involved network nodes could join the VTN and
allocate the network resources for the VTN accordingly. This may be
done with PCEP [RFC5440], Netconf/YANG [RFC6241] [RFC7950] or with
any other control plane mechanism with necessary extensions. Thus,
the controller not only allocates the resources to the newly computed
VTN but also keeps track of the remaining available resources in
order to cope with subsequent VTN requests.
On each network node involved in a VTN, a set of network resources
are allocated to that VTN. Such set of network resources can be
dedicated for the processing of traffic in that VTN, and cannot be
used for traffic in other VTNs. Note it is also possible that a
group of VTNs may share a set of network resources on some network
segments. Resource-aware SIDs are allocated to represent the set of
resources allocated on the network node and the attached links. Such
group of resource-aware SIDs, e.g. prefix-SIDs and adj-SIDs are used
as the data plane identifiers of the node and links in the VTN.
In the underlying forwarding plane, there can be multiple ways of
allocating a subset of network resources to a VTN. The candidate
data plane technologies to support resource partitioning or
reservation can be found in [I-D.ietf-teas-enhanced-vpn]. The
resource-aware SIDs are considered as a unified abstraction in the
network layer, which can work with various network resource partition
or reservation mechanisms in the underlying forwarding plane.
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Node-SIDs: Node-SIDs:
r:101 r:102
g:201 Adj-SIDs: g:202
b:301 r:1001:1G r:1001:1G b:302
+-----+ g:2001:2G g:2001:2G +-----+
| A | b:3001:1G b:3001:1G | B |Adj-SIDs:
| +------------------------+ + r:1003:1G
Adj-SIDs +--+--+ +--+--+\g:2003:2G
r:1002:1G| r:1002:1G| \
g:2002:2G| g:2002:2G| \ r:1001:1G
b:3002:3G| b:3002:2G| \g:2001:2G
| | \ +-----+ Node-SIDs:
| | \+ E | r:105
| | /+ | g:205
r:1001:1G| r:1002:1G| / +-----+
g:2001:2G| g:2002:2G| /r:1002:1G
b:3001:3G| b:3002:2G| / g:2002:2G
+--+--+ +--+--+ /
| | | |/r:1003:1G
| C +------------------------+ D + g:2003:2G
+-----+ r:1002:1G r:1001:1G +-----+
Node-SIDs: g:2002:1G g:2001:1G Node-SIDs:
r:103 b:3002:2G b:3001:2G r:104
g:203 g:204
b:303 b:304
Figure 1. SID and resource allocation for multiple VTNs
Figure 1 shows an example of providing multiple VTNs in an SR based
network. Note that the format of the SIDs in this figure is for
illustration, both SR-MPLS and SRv6 can be used as the data plane.
In this example, three VTNs: red (r) , green (g) and blue (b) are
created to carry traffic of different customers or services. Both
the red and green VTNs consist of nodes A, B, C, D, and E with all
their interconnecting links, whilst the blue VTN only consists of
nodes A, B, C and D with all their interconnecting links. Note that
different VTNs may have a set of shared nodes and links. On each
link, a resource-aware adj-SID is allocated for each VTN it
participates in.
In Figure 1, the notation x:nnnn:y means that in VTN x, the adj-SID
nnnn will steer the packet over a link which has bandwidth y reserved
for that VTN. For example, r:1002:1G in link C->D says that the VTN
red has a reserved bandwidth of 1Gb/s on link C->D, and will be used
by packets arriving at node C with an adj-SID 1002 at the top of the
label stack. Similarly, on each node, a resource-aware prefix-SID is
allocated for each VTN it participates in. The adj-SIDs can be
associated with different set of link resources (e.g. bandwidth)
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allocated to different VTNs, so that the adj-SIDs can be used to
steer service traffic into different set of link resources in packet
forwarding. The prefix-SIDs can be associated with the nodal
resources allocated to different VTNs. In addition, the prefix-SIDs
can be used to build loose SR path within a VTN, in this case it can
be used by the transit nodes to steer service traffic into the set of
local network resources allocated to the VTN.
3.3. Construction of SR based VTNs
The network controller needs to obtain the information of all the
VTNs in the network it oversees, and the network nodes need to obtain
the information of the VTNs they participate in. To achieve this,
each network node needs to advertise the identifiers of the VTNs it
participates in, together with the group of SIDs and the associated
resource attributes both to other network nodes and to the
controller.
[I-D.dong-lsr-sr-enhanced-vpn] defines an IGP mechanism to advertise
the customized topology and resource attributes of VTN, which allows
flexible combination of the virtual network topology and the network
resources attribute to provide a relatively large number of VTNs.
The corresponding BGP-LS mechanism used to distribute the VTN
information to the controller is described in
[I-D.dong-idr-bgpls-sr-enhanced-vpn].
For network scenarios which require less flexibility or scalability,
the simplified control plane mechanisms based on Multi-Topology
[RFC5120] or Flex-Algo [I-D.ietf-lsr-flex-algo] are described in
[I-D.xie-lsr-isis-sr-vtn-mt] and [I-D.zhu-lsr-isis-sr-vtn-flexalgo]
respectively. The corresponding BGP-LS mechanisms used to distribute
the VTN information to the controller are described in
[I-D.xie-idr-bgpls-sr-vtn-mt] and [I-D.zhu-idr-bgpls-sr-vtn-flexalgo]
respectively.
Based on the collected information of the topology, the allocated
network resources and the associated SIDs of VTNs, both the
controller and network nodes can construct the SR based VTNs and
generate the forwarding tables and entries for each VTN based on the
SIDs and SRv6 Locators of each VTN. Unlike classic segment routing
in which network resources on a network segment are shared by all the
SR traffic, different SR VTNs can be associated with different set of
resources allocated in the underlay forwarding plane, so that they
can be used to provide the required resource isolation between
different customers and/or services in the same network.
Figure 2 shows the SR based VTNs created in the network in Figure 1.
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1001 1001 2001 2001 3001 3001
101---------102 201---------202 301---------302
| | \1003 | | \2003 | |
1002| 1002| \ 1001 2002| 2002| \ 2001 3002| 3002|
| | 105 | | 205 | |
1001| 1002| / 1002 2001| 2002| / 2002 3001| 3002|
| | / 1003 | | / 2003 | |
103---------104 203---------204 303---------304
1002 1001 1002 2001 3002 3001
VTN Red VTN Green VTN Blue
Figure 2. SR based VTNs with different groups of SIDs
For each SR based VTN, SR paths are computed within the VTN, taking
the VTN topology and resources as constraints. The SR path can be an
explicit path instantiated using SR policy
[I-D.ietf-spring-segment-routing-policy], in which the SID-list is
built only with the SIDs allocated to the VTN. The SR path can also
be an IGP computed path associated with a prefix-SID or SRv6 End SID
allocated by a node for the VTN, the IGP computation is also based on
the VTN constraints. Different SR paths in the same VTN may use
shared network resources when they use the same resource-aware SIDs
allocated to the VTN, while SR paths in different VTNs can be steered
to use different set of network resources over the shared network
links or nodes. These VTN-specific SR paths need to be installed in
the corresponding forwarding tables.
For example, to create an explicit path A-B-D-E in VTN red in
Figure 2, the SR SID-list encapsulated in the service packet would be
(1001, 1002, 1003). For the same explicit path A-B-D-E in VTN green,
the SR segment list would be (2001, 2002, 2003). In the case where
we wish to construct a loose path A-D-E in VTN green, the service
packet SHOULD be encapsulated with the SR SID-list (201, 204, 205).
At node A, the packet can be sent towards D via either node B or C
using the link and node resources allocated for VTN green. At node D
the packet is forwarded to E using the link and node resource
allocated for VTN green. Similarly, a packet to be sent via loose
path A-D-E in VTN red would be encapsulated with segment list (101,
104, 105). In the case where an IGP computed path can meet the
service requirement, the packet can be simply encapsulated with the
prefix-SID of egress node E in the corresponding VTN.
3.4. Mapping Service to SR based VTN
Network services can be provisioned using SR based VTNs as the
virtual underlay networks. For example, different services may be
provisioned in different SR based VTNs, each of which would use the
network resources allocated to the VTN, so that they will not
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interfere with each other. In another case, a group of services
which have similar characteristics and requirements may be
provisioned in the same VTN, in this case the network resources
allocated to the VTN are only shared among this group of services,
but will not be shared with other services in the network. The
steering of service traffic to SR based VTNs can be based on either
local policy or the mechanisms as defined in
[I-D.ietf-spring-segment-routing-policy].
3.5. VTN Visibility to Customer
The customers may request different granularity of visibility to the
VTN which deliver the service. Depending on the requirement, the
network can be exposed to the customer either as a virtual network
with both the edge nodes and the intermediate nodes, or a set of
paths with some of the transit nodes, or simply a set of virtual
connectivity between endpoints without any transit node information.
The visibility may be delivered through different possible
mechanisms, such as IGPs (e.g. IS-IS, OSPF), BGP-LS or Netconf/YANG.
On the other hand, network operators may want to restrict the
visibility of the network information it delivers to the customer by
either hiding the transit nodes between sites (and only delivering
the endpoints connectivity), or by hiding portions of the transit
nodes (summarizing the path into fewer nodes). Mechanisms such as
BGP-LS allow the flexibility of the advertisement of aggregated
virtual network information.
4. Characteristics of SR based VTN
The proposed mechanism provides several key characteristics:
o Customization: Different customized VTNs can be created in a
shared network to meet different customers' connectivity and
service requirement. Each customer is only aware of the topology
and attributes of his own VTN, and provision services on the VTN
instead of the shared physical network. This provides an
practical mechanism to support network slicing.
o Resource Isolation: The computation and instantiation of SR paths
in one VTN can be independent from other VTNs or other services in
the network. In addition, a VTN can be associated with a set of
dedicated network resources, which can avoid resource competition
and performance interference from other VTNs or other services in
the network. The proposed mechanism also allows resource sharing
between different service flows of the same customer, or between a
group of services which are provisioned in the same VTN. This
gives the operators and the customers the flexibility in network
planning and service provisioning. In a VTN, the performance of
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critical services can be further ensured using other mechanisms,
e.g. those as defined in [DetNet].
o Scalability: The introduction of resource aware SIDs for different
VTNs would increase the amount of SIDs and state in the network.
While the increased network state is considered an inevitable
price in meeting the requirements of some customers or services,
the SR based VTN mechanism seeks to achieve a balance between the
state limitations of traditional end-to-end TE mechanism and the
lack of resource awareness in classic segment routing. Following
the segment routing paradigm, network resources are allocated on
network segments in a per VTN manner and represented as SIDs, this
ensures that there is no per-path state introduced in the network.
In addition, operators can choose the granularity of resource
allocation on different network segments. In network segments
where resource is scarce such that the service requirement may not
always be met, the proposed approach can be used to allocate a set
of resources to a VTN which contains such network segment to avoid
possible competition. By contrast, in other segment of the
network where resource is considered plentiful, the resource may
be shared between a number of VTNs. The decision to do this is in
the hands of the operator. Because of the segmented nature of the
SR based VTN, resource aggregation is easier and more flexible
than RSVP-TE based approach.
5. Service Assurance of VTN
In order to provide assurance for services provisioned in the SR
based VTNs, it is necessary to instrument the network at multiple
levels, e.g. in both the underlay network level and the VTN level.
The operator or the customer may also monitor and measure the
performance of the services carried by the VTN. In principle these
can be achieved using existing or in development techniques in IETF.
The detailed mechanisms are out of the scope of this document.
In case of failure or service performance degradation happens in a
VTN, it is necessary that some recovery mechanisms, e.g. local
protection or end-to-end protection mechanism is used to switch the
traffic to another path in the same VTN which could meet the service
performance requirement. Care must be taken that the service or path
recovery mechanism in one VTN does not impact other VTNs in the same
network.
6. 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.
7. Security Considerations
The security considerations of segment routing and resource-aware
SIDs are applicable to this document.
The SR VTNs may be used carry services with specific SLA parameters.
An attack can be directly targeted at the customer application by
disrupting the SLA, and can be targeted at the network operator by
causing them to violate their SLA, triggering commercial
consequences. By rigorously policing ingress traffic and carefully
provisioning the resources provided to the VTN, this type of attack
can be prevented. However care needs to be taken when shared
resources are provided between VTNs at some point in the network, and
when the network needs to be reconfigured as part of ongoing
maintenance or in response to a failure.
The details of the underlying network should not be exposed to third
parties, some abstraction would be needed, this is also to prevent
attacks aimed at exploiting a shared resource between VTNs.
8. Contributors
Zhenbin Li
Email: lizhenbin@huawei.com
Zhibo Hu
Email: huzhibo@huawei.com
9. Acknowledgements
The authors would like to thank Mach Chen, Stefano Previdi, Charlie
Perkins, Bruno Decraene, Loa Andersson, Alexander Vainshtein, Joel
Halpern and James Guichard for the valuable discussion and
suggestions to this document.
10. References
10.1. Normative References
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
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[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
10.2. Informative References
[DetNet] "DetNet WG", 2016,
<https://datatracker.ietf.org/wg/detnet>.
[I-D.dong-idr-bgpls-sr-enhanced-vpn]
Dong, J., Hu, Z., Li, Z., Tang, X., and R. Pang, "BGP-LS
Extensions for Segment Routing based Enhanced VPN", draft-
dong-idr-bgpls-sr-enhanced-vpn-02 (work in progress), June
2020.
[I-D.dong-lsr-sr-enhanced-vpn]
Dong, J., Hu, Z., Li, Z., Tang, X., Pang, R., JooHeon, L.,
and S. Bryant, "IGP Extensions for Segment Routing based
Enhanced VPN", draft-dong-lsr-sr-enhanced-vpn-04 (work in
progress), June 2020.
[I-D.ietf-idr-bgpls-segment-routing-epe]
Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray,
S., and J. Dong, "BGP-LS extensions for Segment Routing
BGP Egress Peer Engineering", draft-ietf-idr-bgpls-
segment-routing-epe-19 (work in progress), May 2019.
[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-13 (work in progress), October 2020.
[I-D.ietf-spring-resource-aware-segments]
Dong, J., Bryant, S., Miyasaka, T., Zhu, Y., Qin, F., Li,
Z., and F. Clad, "Introducing Resource Awareness to SR
Segments", draft-ietf-spring-resource-aware-segments-00
(work in progress), July 2020.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-09 (work in progress),
November 2020.
Dong, et al. Expires June 6, 2021 [Page 13]
Internet-Draft SR for VPN+ December 2020
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-26 (work in
progress), November 2020.
[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.xie-idr-bgpls-sr-vtn-mt]
Xie, C., Li, C., Dong, J., and Z. Li, "BGP-LS with Multi-
topology for Segment Routing based Virtual Transport
Networks", draft-xie-idr-bgpls-sr-vtn-mt-01 (work in
progress), July 2020.
[I-D.xie-lsr-isis-sr-vtn-mt]
Xie, C., Ma, C., Dong, J., and Z. Li, "Using IS-IS Multi-
Topology (MT) for Segment Routing based Virtual Transport
Network", draft-xie-lsr-isis-sr-vtn-mt-02 (work in
progress), October 2020.
[I-D.zhu-idr-bgpls-sr-vtn-flexalgo]
Zhu, Y., Dong, J., and Z. Hu, "BGP-LS with Flex-Algo for
Segment Routing based Virtual Transport Networks", draft-
zhu-idr-bgpls-sr-vtn-flexalgo-00 (work in progress), March
2020.
[I-D.zhu-lsr-isis-sr-vtn-flexalgo]
Zhu, Y., Dong, J., and Z. Hu, "Using Flex-Algo for Segment
Routing based VTN", draft-zhu-lsr-isis-sr-vtn-flexalgo-01
(work in progress), September 2020.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
Dong, et al. Expires June 6, 2021 [Page 14]
Internet-Draft SR for VPN+ December 2020
[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>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
<https://www.rfc-editor.org/info/rfc7471>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March
2019, <https://www.rfc-editor.org/info/rfc8570>.
Dong, et al. Expires June 6, 2021 [Page 15]
Internet-Draft SR for VPN+ December 2020
[RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
IGP Traffic Engineering Performance Metric Extensions",
RFC 8571, DOI 10.17487/RFC8571, March 2019,
<https://www.rfc-editor.org/info/rfc8571>.
Authors' Addresses
Jie Dong
Huawei Technologies
Email: jie.dong@huawei.com
Stewart Bryant
Futurewei Technologies
Email: stewart.bryant@gmail.com
Takuya Miyasaka
KDDI Corporation
Email: ta-miyasaka@kddi.com
Yongqing Zhu
China Telecom
Email: zhuyq8@chinatelecom.cn
Fengwei Qin
China Mobile
Email: qinfengwei@chinamobile.com
Zhenqiang Li
China Mobile
Email: li_zhenqiang@hotmail.com
Francois Clad
Cisco Systems
Email: fclad@cisco.com
Dong, et al. Expires June 6, 2021 [Page 16]