SPRING Working Group J. Dong
Internet-Draft Huawei Technologies
Intended status: Informational S. Bryant
Expires: March 4, 2021 Futurewei Technologies
T. Miyasaka
KDDI Corporation
Y. Zhu
China Telecom
F. Qin
Z. Li
China Mobile
F. Clad
Cisco Systems
August 31, 2020
Segment Routing based Virtual Transport Network for Enhanced VPN
draft-dong-spring-sr-for-enhanced-vpn-10
Abstract
I-D.ietf-spring-resource-aware-segments describes the mechanism to
associate network resource attributes to Segment Routing Identifiers
(SIDs). The resource-aware SIDs can be used to build SR paths with a
set of reserved network resources. In addition, the resource-aware
SIDs can be used to build SR based virtual networks, which can be
used as virtual underlay networks with the network topology and
resource attributes required by different customers or services.
Such virtual networks are called virtual transport networks (VTNs).
This document describes the mechanism of using resource-aware SIDs to
build SR based VTNs.
Status of This Memo
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This Internet-Draft will expire on March 4, 2021.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Resource-Aware SIDs for VTN . . . . . . . . . . . . . . . . . 3
2.1. SR-MPLS . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. SRv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. VTN Topology and Resource Computation . . . . . . . . . . 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 . . . . . . . . . . . . . . . 9
4. Benefits of the Proposed Mechanism . . . . . . . . . . . . . 10
5. Service Assurance . . . . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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. While
compared with RSVP-TE [RFC3209], currently SR does not have the
capability of reserving network resources or identifying a set of
network resources reserved for services or customers.
[I-D.ietf-spring-resource-aware-segments] extends the SR paradigm by
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associating SIDs with network resource attributes. On a network
segment, multiple resource-aware SIDs can be allocated, each of which
represents a subset of network resources allocated to meet the
requirement of some customers or services. The resource-aware SIDs
can be used to build SR paths with a set of reserved network
resources. In addition, the resource-aware SIDs can also be used to
build SR based virtual networks with the required network topology
and resource attributes. A group of resource-aware SIDs together can
be used to specify the customized topology of a virtual network, and
can further be used to steer the service traffic to be processed with
the set of network resources allocated to the virtual network. Such
virtual networks are called virtual transport networks (VTNs), which
can be used as the underlay of enhanced VPN services as described in
[I-D.ietf-teas-enhanced-vpn].
This document describes the mechanism of using 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 that SR paths in a VTN are computed with the
topology constraints, and are instantiated with 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, and each SID can be used to
identify both the network topology and the set of network resources
allocated on the network segment for a VTN. The mechanisms to
identify the network topology or forwarding path with a SID as
defined in [RFC8402] are reused, and the control plane can be based
on [RFC4915], [RFC5120] and [I-D.ietf-lsr-flex-algo].
2.1. SR-MPLS
For one IGP link, multiple Adj-SIDs are allocated, each of which is
associated with a VTN the link participates, 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 participate, and represent 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
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multiple domains, and represents a subset of resources allocated on
the inter-domain link.
This way, a group of resource-aware SIDs associated with the same VTN
can be used to represent the VTN topology and the allocated resources
in data plane. An SR SID-list built with such group of SIDs can be
used to steer service traffic to follow a path within the VTN
topology, and each SID in the SID-list can also be used to steer the
service traffic to be processed with the set of network resources
allocated to the VTN.
Note that the introduction of SR-MPLS based VTN increases the number
of SIDs needed, and the amount network states is also increased.
While thanks to the SR paradigmn, the resource-aware SIDs are
associated with different VTNs rather than different paths, thus per-
path state is still avoided inside the SR network.
2.2. SRv6
In order to support multiple VTNs with SRv6, network nodes (including
both the edge nodes and transit nodes) belonging to the same VTN need
to have a consistent view of the VTN, and perform consistent
computation and forwarding behavior to comply to the VTN topology and
resource constraints. The mechanisms to ensure the consistency of
such view can be based on [RFC4915], [RFC5120] and
[I-D.ietf-lsr-flex-algo]. In data plane, some mechanism is needed
for nodes to identify the VTN a packets belongs to.
Based on the mechanisms defined in
[I-D.ietf-spring-resource-aware-segments], for a network node,
multiple SRv6 LOCs are allocated, each of which is associated with a
VTN it participates, and represents a subset of the network resources
allocated to the VTN. The SRv6 SIDs of a particular VTN are
allocated from the SID space using the VTN-specific LOC as the
prefix. These SRv6 SIDs can be used to represent VTN-specific local
functions.
A group of SRv6 SIDs associated with the same VTN can be used to
represent the VTN topology and the allocated resources in data plane.
An SRv6 SID-list built with such SIDs can be used to steer the
service traffic to follow a path within the VTN topology, and each
SID in the SID-list can also be used to steer the service traffic to
be processed with the set of network resources allocated to the VTN.
Note that the introduction of SRv6 based VTN increases the number of
SRv6 Locators and SIDs needed, and the amount network states is also
increased. While thanks to the SR paradigmn, the resource-aware SIDs
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are associated with different VTNs rather than different paths, thus
per-path state is still avoided in the SR network.
3. Procedures
This section describes the procedures of 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.
According to the received service requirement, a centralized network
controller calculates a subset of the 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 a individual service or customer, or can be shared by a
group of services or customers.
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 is considered as the virtual underlay network for the
service. Control plane protocols such as IGP and BGP-LS needs to be
extended to distribute the SIDs and the associated resource
information of each VTN. The detailed control plane extensions are
out of the scope of this document.
Suppose a virtual network is requested by some customer or service.
The basic requirement is that customer or service is allocated with
some dedicated network resource and does not experience unexpected
interference from other services in the same network. Other possible
requirements may include the required topology, bandwidth, latency,
reliability, etc.
3.1. VTN Topology and Resource Computation
A centralized network controller can be responsible for the planning
of a VTN to meet the received service request. The controller needs
to collect the information of network connectivity, network
resources, network performance and other relevant network states of
the underlay network. This can be done using either IGP [RFC5305]
[RFC3630] [RFC7471] [RFC8570] or BGP-LS [RFC7752] [RFC8571].
Based on the information collected from the underlay network, the
controller obtains the underlay network topology and the information
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about the allocated and available network resources. When a service
request is received, the controller computes 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 accordingly. This can be done with
either PCEP [RFC5440] or Netconf/YANG [RFC6241] [RFC7950] with
necessary extensions. On each network node involved in the VTN, a
set of network resources are allocated on a per virtual network
basis, and a group of 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 data plane identifiers of the node and links in the
VTN.
In underlying forwarding plane, there can be multiple ways of
partitioning and allocating a set of network resource to a VTN. For
example, [FLEXE] may be used to partition the link resource into
different sub-channels to achieve resource isolation between each
other. The candidate data plane technologies to support resource
partitioning can be found in [I-D.ietf-teas-enhanced-vpn]. The SR
SIDs are considered as a unified abstraction in network layer , which
can work with various network resource partition and allocation
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 different 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)
allocated to different VTNs, so that the adj-SIDs can be used to
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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 each 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 in forwarding
plane.
3.3. Construction of SR based VTNs
In order to make both the network controller and network nodes aware
of the information of the VTNs in the network, 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 the controller. This can
be achieved by IGP extensions in [I-D.dong-lsr-sr-enhanced-vpn] and
BGP-LS extensions in[I-D.dong-idr-bgpls-sr-enhanced-vpn].
Based on the collected information of the topology, the allocated
network resource information and the associated SIDs of VTN, the
controller and network nodes are able to construct the SR based VTNs
and generate the forwarding tables and entries of each VTN based on
the prefix-SIDs and adj-SIDs 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 meet the enhanced service
requirement and provide the required resource isolation from other
services in the same network.
Figure 2 shows the SR based VTNs created in the network in Figure 1.
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
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[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 of the VTN, the
IGP computation is based on the VTN constraints. Different SR paths
in the same VTN may use shared network resources according to the
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 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 customized SR based VTN as
the underlay network. 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
interfere with each other. In another case, a group of services
which have similar characteristics and requirement 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
mechanisms as defined in [I-D.ietf-spring-segment-routing-policy].
3.5. VTN Visibility to Customer
The customer may request different granularity of visibility to the
network which deliver the service. Depending on the requirement, the
network can be exposed to the customer either as a virtual network,
or a set of computed paths with transit nodes, or simply the abstract
connectivity between endpoints without any path information. The
visibility can be delivered through different possible mechanisms,
such as IGPs (e.g. IS-IS, OSPF) or BGP-LS. In addition, network
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operator may want to restrict the visibility of the 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. Benefits of the Proposed Mechanism
The proposed mechanism provides several key characteristics:
o Flexibility: Multiple 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 physical network. This provides an efficient
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
network resources, which can avoid resource competition and
performance interference from 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 operator
and the customers the flexibility in network planning and service
provisioning. The performance of critical services can be further
ensured using the mechanisms defined in [DetNet].
o Scalability: The introduction of resource guaranteed paths or
virtual networks would increase the amount of state to the
network. The proposed 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 per VTN and
represented as SIDs, thus there is no per-flow state introduced in
the network. Operator can choose the granularity of resource
allocation to 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
specific resources to a VTN which contains such network segment.
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
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aggregation is easier and more flexible than RSVP-TE based
approach.
5. Service Assurance
In order to provide service assurance for services provisioned in the
SR based VTNs, it is necessary to instrument the network at multiple
levels. The network operator needs to ascertain that the underlay
network is operating correctly. A tenant needs to ascertain that
their services are operating correctly. In principle these can use
existing techniques. These are well known problems and solutions
either exist or are in development to address them.
New work may be needed to instrument the VTNs that are created for
particular services. Such instrumentation needs to operate without
causing disruption to other services using the network. Given the
sensitivity of some applications, care needs to be taken to ensure
that the instrumentation itself does not cause disruption either to
the service being instrumented or to other services. In case of
failure or performance degradation of a service path in a particular
VTN, it is necessary that either local protection or end-to-end
protection mechanism is used to switch to another path in the same
VTN which could meet the service performance requirement and does not
impact other services in the network.
6. IANA Considerations
This document makes no request of IANA.
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.
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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 and Joel
Halpern 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>.
[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>.
[FLEXE] "Flex Ethernet Implementation Agreement", March 2016,
<http://www.oiforum.com/wp-content/uploads/OIF-FLEXE-
01.0.pdf>.
[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.
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[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-10 (work in progress), August 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-08 (work in progress),
July 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-18 (work in
progress), August 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.
[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>.
Dong, et al. Expires March 4, 2021 [Page 13]
Internet-Draft SR for VPN+ August 2020
[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>.
[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>.
Dong, et al. Expires March 4, 2021 [Page 14]
Internet-Draft SR for VPN+ August 2020
[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>.
[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
Dong, et al. Expires March 4, 2021 [Page 15]
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Francois Clad
Cisco Systems
Email: fclad@cisco.com
Dong, et al. Expires March 4, 2021 [Page 16]