Internet DRAFT - draft-dong-lsvr-bgp-spf-nrp
draft-dong-lsvr-bgp-spf-nrp
LSVR Working Group J. Dong
Internet-Draft Z. Li
Intended status: Standards Track H. Wang
Expires: 22 April 2024 Huawei Technologies
J. Ge
China Academy of Information and Communications Technology
20 October 2023
BGP SPF for Network Resource Partitions
draft-dong-lsvr-bgp-spf-nrp-02
Abstract
A VTN is a virtual underlay network which has customized network
topology and a set of dedicated or shared network resources. Network
Resource Partition (NRP) refers to a set of network resources that
are available to carry traffic and meet the SLOs and SLEs. Multiple
NRPs can be created in a network to provide different Virtual
Transport Networks (VTN) to meet the requirements of different
services or different service groups.
As the number of NRP increases, there can be scalability concerns
about using Interial Gateway Protocols (IGP) to distribute the NRP
information in the network. In networks where BGP Shortest Path
First (SPF) can used as the underlay routing mechanism to distribute
the link-state information among network nodes, the information of
NRPs needs to be distributed along with the basic network
information. This document specifies the BGP SPF mechanisms with
necessary extensions to distribute the NRP information and perform
NRP-specific path computation.
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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Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 22 April 2024.
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Copyright Notice
Copyright (c) 2023 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
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Applicability of NRP related BGP-LS Extensions to BGP SPF . . 3
2.1. Reuse of BGP-LS TLVs for BGP SPF VTN . . . . . . . . . . 3
2.2. NRP Topology and Resource Distribution . . . . . . . . . 5
3. SPF Calculation for NRPs . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The concept of Virtual Transport Network (VTN) is introduced in
[I-D.ietf-teas-enhanced-vpn]. A VTN is a virtual underlay network
which has customized network topology and a set of dedicated or
shared network resources. In a network, different VTNs may be
created to meet different service requirements, and services can be
mapped to the same or different VTNs.
[I-D.ietf-teas-ietf-network-slices] introduces the concept Network
Resource Partition (NRP) as a set of network resources that are
available to carry traffic and meet the SLOs and SLEs. In the
context of network slicing, an NRP can be used to instantiate a VTN
for one or a group of IETF network slice services. In the context of
network slicing, an NRP can be used to instantiate a VTN for one or a
group of IETF network slice services.
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[I-D.ietf-spring-sr-for-enhanced-vpn] describes the use of resource-
aware segments [I-D.ietf-spring-resource-aware-segments] to build SR
based NRPs. The SIDs of each NRP and the associated topology and
resource attributes need to be distributed using the control plane.
[I-D.dong-lsr-sr-enhanced-vpn] specifies the IGP mechanism and
extensions to build a relatively large number of SR based NRPs.
[I-D.dong-idr-bgpls-sr-enhanced-vpn] further specifies the BGP-LS
mechanisms and extensions to advertise the NRP information within
each domain and the NRP information on the inter-domain links to the
network controller, so that the controller could use the collected
information to obtain the view of the inter-domain SR NRPs .
As the number of NRP increases, there can be scalability concerns
about using IGP to distribute the NRP information in the network. In
networks where BGP SPF is used to distribute the link-state
information among network nodes, the NRP information needs to be
distributed along with the basic network link state and TE
information. Comparing with the Internal Gateway Protocols (IGPs),
BGP SPF may have some advantage in supporting a relatively large
number of NRPs. This document specifies the BGP SPF mechanisms with
necessary extensions to advertise the information of NRPs. The
proposed mechanism is applicable to segment routing with MPLS data
plane (SR-MPLS), segment routing with IPv6 data plane (SRv6), and
native IPv6 data plane.
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. Applicability of NRP related BGP-LS Extensions to BGP SPF
2.1. Reuse of BGP-LS TLVs for BGP SPF VTN
As described in [I-D.ietf-lsvr-bgp-spf], the NLRI and TLVs of BGP-LS
can be reused by BGP SPF, this section describes the TLVs which are
defined in BGP-LS and can be reused in BGP SPF for the distribution
of NRP related information.
According to [I-D.ietf-teas-enhanced-vpn], a virtual transport
network (VTN) has a customized network topology and a set of
dedicated or shared network resources. Thus a VTN can be defined as
the combination of a set of network attributes, including the
topology attribute and the network resource attribute. As the
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instantiation of VTN, an NRP is associated with a Multi-Topology ID
(MT-ID) and/or an Algorithm ID which are used to define the NRP
topology and path computation constraints. In some cases, each NRP
can be associated with a separate MT-ID or a Flex-Algo ID. When the
amount of NRPs in a network is large, as described in
[I-D.ietf-teas-nrp-scalability], multiple NRPs may be associated with
the same topology and/or algorithm, so that the amount of topology-
specific path computation can be shared by a group of NRPs, this
could help to reduce the computation overhead in the control plane.
[I-D.ietf-lsvr-bgp-spf] does not cover the usage of Multi-Topology or
Flex-Algo with BGP SPF. This document proposes to use Multi-Topology
[RFC4915][RFC5120] or Flex-Algo [RFC9350] with BGP SPF for topology
and/or algorithm -specific link-state information distribution and
path computation. For this purpose, the Multi-topology TLV as
defined in [I-D.ietf-idr-rfc7752bis], the SR Algorithm TLV as defined
[RFC9085], and the Flex-Algo Definition TLV as defined in
[I-D.ietf-idr-bgp-ls-flex-algo] are reused for BGP SPF.
[I-D.ietf-lsvr-bgp-spf] does not explicitly describe the usage with
Segment Routing data plane. To build SR based NRPs, the SR-MPLS and
SRv6 TLVs as defined in [RFC9085] and [I-D.ietf-idr-bgpls-srv6-ext]
are reused for BGP SPF.
The NRP extensions to BGP-LS as defined in
[I-D.dong-idr-bgpls-sr-enhanced-vpn] applies to BGP SPF as well.
This section lists the TLVs which are reused by BGP SPF, the detailed
format of the TLVs are described in
[I-D.dong-idr-bgpls-sr-enhanced-vpn].
The BGP-LS Attribute TLVs which are defined in
[I-D.dong-idr-bgpls-sr-enhanced-vpn] and reused with BGP-LS-SPF SAFI
are listed as below:
* NRP Definition (NRPD) TLV: This is used to advertise the
association between the NRP and the topology ID and/or algorithm
ID. It can be carried in BGP-LS attribute associated with a Node
NLRI.
* NRP IDs TLV: This is used to describe the identifiers of one or
more NRPs which are associated with a specific set of network
resources. It can be carried in BGP-LS attribute which is
associated with a Link NLRI, or it could be carried as a sub-TLV
in the L2 Bundle Member Attribute TLV or the NRP-specific TE
attribute TLV.
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* Link Attribute Flags TLV: This is used to specify the
characteristics of a link, its functionality is similar to the IS-
IS Link Attribute sub-TLV defined in [RFC5029]. It can be carried
in BGP-LS attribute which is associated with a Link NLRI, or it
could be carried as a sub-TLV in the L2 Bundle Member Attribute
TLV.
* NRP-specific prefix-SID TLV: This is used to advertise the prefix-
SID and its associated NRP. It can be carried in BGP-LS attribute
which is associated with a Prefix NLRI.
* NRP-specific Adj-SID TLV: This is used to advertise the adj-SID
and its associated NRP. It can be carried in BGP-LS attribute of
the associated Link NLRI.
* NRP Locator-block sub-TLV: This is used to advertise the SRv6
locator block and its associated NRP. It can be carried in the
SRv6 Locator TLV of the associated Prefix NLRI.
* NRP ID Sub-TLV. This is used to advertise the relationship
between SRv6 End.X SIDs and its associated NRP.
Further BGP-LS TLVs may be defined in
[I-D.dong-idr-bgpls-sr-enhanced-vpn], their usage with BGP SPF will
be specified in a future version of this document.
2.2. NRP Topology and Resource Distribution
In network scenarios where each NRP is associated with a unique MT-
ID, The BGP-LS mechanisms used to distribute the NRP topology and
resource information to the network controller are described in
[I-D.ietf-idr-bgpls-sr-vtn-mt]. Such mechanism can be reused for the
distribution of NRP information with BGP SPF.
In network scenarios where each NRP is associated with a unique Flex-
Algo ID, The BGP-LS mechanisms used to distribute the NRP topology
and resource information to the network controller are described in
[I-D.zhu-idr-bgpls-sr-vtn-flexalgo]. Such mechanism can be reused
for the distribution of NRP information with BGP SPF.
In network scenarios where multiple NRPs are associated with the same
<topology, algorithm> tuple, while each NRP has different resource
attributes, the BGP-LS mechanisms which can be used to distribute the
NRP topology and resource information to the network controller are
described in [I-D.dong-idr-bgpls-sr-enhanced-vpn]. Such mechanism
can be reused for the distribution of NRP information with BGP SPF.
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The Sequence Number TLV as defined in [I-D.ietf-lsvr-bgp-spf] MUST be
carried in the BGP-LS attribute associated with the BGP-LS-SPF NLRI.
If the Sequence-Number TLV is not received then the corresponding
Link NLRI is considered as malformed and MUST be handled as 'Treat-
as- withdraw'. An implementation MAY log an error for further
analysis.
3. SPF Calculation for NRPs
[I-D.ietf-lsvr-bgp-spf] describes the mechanisms of using the BGP-LS-
SPF Node, Link, and Prefix NLRIs for shortest path computation. With
the introduction of NRP, the same mechanism is used for the shortest
path computation of each NRP. The path computation for a NRP is
based on the topology attributes and the constraints specified with
the MT-ID and/or Algorithm ID associated with the NRP. When multiple
NRPs are associated with the same <topology, algorithm> tuple, the
result of the shortest path computation based on that <topology,
algorithm> could be shared by these NRPs.
4. Security Considerations
This document introduces no additional security vulnerabilities to
BGP SPF.
The mechanism proposed in this document is subject to the same
vulnerabilities as any other protocol that relies on BGP SPF.
5. IANA Considerations
This document request no IANA actions.
6. Acknowledgments
TBD
7. References
7.1. Normative References
[I-D.dong-idr-bgpls-sr-enhanced-vpn]
Dong, J., Hu, Z., Li, Z., Tang, X., and R. Pang, "BGP-LS
Extensions for Scalable Segment Routing based Enhanced
VPN", Work in Progress, Internet-Draft, draft-dong-idr-
bgpls-sr-enhanced-vpn-04, 4 March 2022,
<https://datatracker.ietf.org/doc/html/draft-dong-idr-
bgpls-sr-enhanced-vpn-04>.
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[I-D.ietf-idr-bgp-ls-flex-algo]
Talaulikar, K., Psenak, P., Zandi, S., and G. Dawra,
"Flexible Algorithm Advertisement using BGP Link-State",
Work in Progress, Internet-Draft, draft-ietf-idr-bgp-ls-
flex-algo-12, 24 August 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
ls-flex-algo-12>.
[I-D.ietf-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
Bernier, D., and B. Decraene, "BGP Link State Extensions
for SRv6", Work in Progress, Internet-Draft, draft-ietf-
idr-bgpls-srv6-ext-14, 17 February 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
bgpls-srv6-ext-14>.
[I-D.ietf-idr-rfc7752bis]
Talaulikar, K., "Distribution of Link-State and Traffic
Engineering Information Using BGP", Work in Progress,
Internet-Draft, draft-ietf-idr-rfc7752bis-17, 25 August
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
idr-rfc7752bis-17>.
[I-D.ietf-lsvr-bgp-spf]
Patel, K., Lindem, A., Zandi, S., and W. Henderickx, "BGP
Link-State Shortest Path First (SPF) Routing", Work in
Progress, Internet-Draft, draft-ietf-lsvr-bgp-spf-28, 29
August 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-lsvr-bgp-spf-28>.
[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", Work in Progress, Internet-Draft, draft-ietf-
spring-resource-aware-segments-07, 31 May 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
resource-aware-segments-07>.
[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+)",
Work in Progress, Internet-Draft, draft-ietf-teas-
enhanced-vpn-14, 28 July 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
enhanced-vpn-14>.
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[I-D.ietf-teas-ietf-network-slices]
Farrel, A., Drake, J., Rokui, R., Homma, S., Makhijani,
K., Contreras, L. M., and J. Tantsura, "A Framework for
Network Slices in Networks Built from IETF Technologies",
Work in Progress, Internet-Draft, draft-ietf-teas-ietf-
network-slices-25, 14 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
ietf-network-slices-25>.
[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>.
[RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., and M. Chen, "Border Gateway Protocol - Link State
(BGP-LS) Extensions for Segment Routing", RFC 9085,
DOI 10.17487/RFC9085, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
7.2. Informative References
[I-D.dong-lsr-sr-enhanced-vpn]
Dong, J., Hu, Z., Li, Z., Tang, X., Pang, R., and S.
Bryant, "IGP Extensions for Scalable Segment Routing based
Virtual Transport Network (VTN)", Work in Progress,
Internet-Draft, draft-dong-lsr-sr-enhanced-vpn-09, 10 July
2023, <https://datatracker.ietf.org/doc/html/draft-dong-
lsr-sr-enhanced-vpn-09>.
[I-D.ietf-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", Work in Progress, Internet-Draft, draft-ietf-
idr-bgpls-sr-vtn-mt-03, 10 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
bgpls-sr-vtn-mt-03>.
[I-D.ietf-spring-sr-for-enhanced-vpn]
Dong, J., Bryant, S., Miyasaka, T., Zhu, Y., Qin, F., Li,
Z., and F. Clad, "Segment Routing based Virtual Transport
Network (VTN) for Enhanced VPN", 12 February 2021,
<https://tools.ietf.org/html/draft-ietf-spring-sr-for-
enhanced-vpn>.
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[I-D.ietf-teas-nrp-scalability]
Dong, J., Li, Z., Gong, L., Yang, G., Guichard, J.,
Mishra, G. S., Qin, F., Saad, T., and V. P. Beeram,
"Scalability Considerations for Network Resource
Partition", Work in Progress, Internet-Draft, draft-ietf-
teas-nrp-scalability-02, 2 June 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
nrp-scalability-02>.
[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", Work in
Progress, Internet-Draft, draft-zhu-idr-bgpls-sr-vtn-
flexalgo-01, 22 February 2021,
<https://datatracker.ietf.org/doc/html/draft-zhu-idr-
bgpls-sr-vtn-flexalgo-01>.
[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>.
[RFC5029] Vasseur, JP. and S. Previdi, "Definition of an IS-IS Link
Attribute Sub-TLV", RFC 5029, DOI 10.17487/RFC5029,
September 2007, <https://www.rfc-editor.org/info/rfc5029>.
[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>.
[RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
DOI 10.17487/RFC9350, February 2023,
<https://www.rfc-editor.org/info/rfc9350>.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: jie.dong@huawei.com
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Zhenbin Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: lizhenbin@huawei.com
Haibo Wang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: rainsword.wang@huawei.com
Jian Ge
China Academy of Information and Communications Technology
China
Email: gejian@caict.ac.cn
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