IDR R. Chen
Internet-Draft ZTE Corporation
Intended status: Standards Track J. Dong
Expires: 20 January 2025 Huawei
D. Zhao
ZTE Corporation
L. Gong
China mobile
Y. Zhu
China Telecom
R. Pang
China Unicom
19 July 2024
SR Policies Extensions for Network Resource Partition in BGP-LS
draft-chen-idr-bgp-ls-sr-policy-nrp-09
Abstract
A Network Resource Partition (NRP) is a subset of the network
resources and associated policies on each of a connected set of links
in the underlay network. An NRP ID is an important network resource
attribute associated with the Segment Routing (SR) policy and needs
to be reported to the external components. This document defines a
new TLV which enables the headend to report the NRP which the SR
Policy Candidate Path (CP) is associated with using Border Gateway
Protocol Link-State (BGP-LS).
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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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 20 January 2025.
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Copyright Notice
Copyright (c) 2024 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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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Carrying NRP TLV in BGP-LS . . . . . . . . . . . . . . . . . 3
3. Scalability Considerations . . . . . . . . . . . . . . . . . 5
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Informative References . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Segment Routing (SR) Policy [RFC9256] is an ordered list of segments
(i.e. instructions) that represent a source-routed policy. Packet
flows are steered into a SR Policy on a node where it is instantiated
called a headend node. The packets steered into an SR Policy carry
an ordered list of segments associated with that SR Policy.
[RFC9543] provides the definition of IETF network slice for use
within the IETF and discusses the general framework for requesting
and operating IETF Network Slices, their characteristics, and the
necessary system components and interfaces.It also introduces the
concept Network Resource Partition (NRP), which is a subset of the
resources and associated policies in the underlay network.
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[I-D.ietf-teas-nrp-scalability] introduces a scalable data plane
approach to support Network Slice is to carry a dedicated NRP ID in
the data packet to identify the NRP the packet belongs to, so that
the packet can be processed and forwarded using the subset of network
resources allocated to the NRP. For SR Policy with IPv6 data plane,
the approach to encapsulate the NRP ID in IPv6 Hop-by-Hop Options
header is defined in [I-D.ietf-6man-enhanced-vpn-vtn-id]. For SR
Policy with MPLS data plane, one approach to encapsulate the NRP ID
to the packet is defined in [I-D.li-mpls-mna-nrp-selector].
[I-D.ietf-idr-sr-policy-nrp] defines the extensions to BGP SR policy
to specify the NRP which the SR Policy candidate path is associated
with.
[I-D.ietf-idr-bgp-ls-sr-policy] describes a mechanism to distribute
SR policy information to external components using BGP-LS. SR policy
information can be used by external components for path computation,
re-optimization, service placement, network visualization, etc.
A Network Resource Partition (NRP) is a subset of the network
resources and associated policies on each of a connected set of links
in the underlay network. The SR policy indicates the forwarding path
of the data packet, and the NRP ID indicates the reserved resources
along the path specified by the SR policy. By associating the SR
policy with a specific NRP, the forwarding path and resource
reservation along the path are ensured. BGP-LS reports the
association between SR Policy Candidate Path (CP) and NRP-ID, which
is used to synchronize the association information between the SR
Policy CP and the NRP-ID.
This document defines a new TLV which enables the headend to report
the NRP which the SR Policy CP is associated with by using BGP-LS.
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Carrying NRP TLV in BGP-LS
A SR Policy CP may be instantiated with a specific NRP on the headend
node via a local configuration, PCEP, or BGP SR Policy signaling.
Then the state and attributes of the NRP associated with the
candidate path of SR policy can be distributed to the controller.
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In order to collect configuration and states of the NRP SR policy,
this document defines a new SR Policy state TLV called the NRP TLV
which enables the headend to report the state at the SR Policy CP
level.
This TLV is carried in the optional non-transitive BGP Attribute
"LINK_STATE Attribute" defined in [RFC9552] associated with the SR
Policy CP NLRI type.
This TLV is optional and only one these TLVs is advertised for a
given SR Policy CP. If multiple TLVs are present, then the first one
is considered valid and the rest are ignored as describe in
[I-D.ietf-idr-bgp-ls-sr-policy].
The TLV has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NRP ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: TBD.
Length: 8-octet. The total length of the value field not including
Type and Length fields.
Flag: 2-octet flag field. None is defined at this stage. The flags
SHOULD be set to zero on transmission and MUST be ignored on receipt.
RESERVED: 2-octet reserved bits. It SHOULD be set to zero on
transmission and MUST be ignored on receipt.
NRP ID: 4-octet domain significant identifier of Network Resource
Partition. Value 0 and 0xFFFFFFFF are reserved. NRP ID is planned
by network operator.
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3. Scalability Considerations
The mechanism specified in this document defines a mechanism for the
headend of the SR policy to report configuration and states of an SR
policy carrying the NRP information by using BGP-LS. Although the
proposed mechanism allows an NRP may support many SR policies, in
normal case the association between the SR Policy and the NRP is
considered to be 1:1. As the number of NRP increases, the number of
SR Policies would also increase accordingly, and the status reported
by the headend increases accordingly. However, the relationship
between the SR Policy and the NRP is relatively stable and does not
change status frequently. On the other hand this will only cause an
increase in the status reporting information of the head node, the
impacts to the BGP control plane are considered acceptable.
4. Acknowledgements
The authors would like to thank Susan Hares, Joel Halpern, Ketan
Talaulikar, Vishnu Pavan Beeram, Adrian Farrel, and Changwang Lin for
their review and discussion of this document.
5. IANA Considerations
IANA maintains a registry group called "Border Gateway Protocol -
Link State (BGP-LS) Parameters" with a registry called "BGP-LS NLRI
and Attribute TLVs". The following TLV codepoints are suggested (for
early allocation by IANA):
Codepoint Description Reference
----------------------------------------------------------
TBD NRP This document
6. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the "Security
Considerations"section of [RFC4271] for a discussion of BGP security.
Security considerations for acquiring and distributing BGP-LS
information are discussed in [RFC9552]. Security considerations for
acquiring and distributing BGP-LS SR Policy information are discussed
in [I-D.ietf-idr-sr-policy-nrp].
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Additionally, it may be considered that reporting the NRP ID in
association with the SR policy constitutes a risk to confidentiality
of mission-critical or commercially sensitive information about the
network. It is the responsibility of the network operator to ensure
that only trusted nodes (that include both routers and controller
applications) within the SR domain are configured to receive such
information.
7. Informative References
[I-D.ietf-6man-enhanced-vpn-vtn-id]
Dong, J., Li, Z., Xie, C., Ma, C., and G. S. Mishra,
"Carrying Network Resource Partition (NRP) Information in
IPv6 Extension Header", Work in Progress, Internet-Draft,
draft-ietf-6man-enhanced-vpn-vtn-id-07, 8 July 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-6man-
enhanced-vpn-vtn-id-07>.
[I-D.ietf-idr-bgp-ls-sr-policy]
Previdi, S., Talaulikar, K., Dong, J., Gredler, H., and J.
Tantsura, "Advertisement of Segment Routing Policies using
BGP Link-State", Work in Progress, Internet-Draft, draft-
ietf-idr-bgp-ls-sr-policy-04, 20 March 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
ls-sr-policy-04>.
[I-D.ietf-idr-sr-policy-nrp]
Dong, J., Hu, Z., and R. Pang, "BGP SR Policy Extensions
for Network Resource Partition", Work in Progress,
Internet-Draft, draft-ietf-idr-sr-policy-nrp-01, 28 June
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
idr-sr-policy-nrp-01>.
[I-D.ietf-teas-nrp-scalability]
Dong, J., Li, Z., Gong, L., Yang, G., and G. S. Mishra,
"Scalability Considerations for Network Resource
Partition", Work in Progress, Internet-Draft, draft-ietf-
teas-nrp-scalability-05, 5 July 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
nrp-scalability-05>.
[I-D.li-mpls-mna-nrp-selector]
Li, T., Drake, J., Beeram, V. P., Saad, T., and I. Meilik,
"MPLS Network Actions for Network Resource Partition
Selector", Work in Progress, Internet-Draft, draft-li-
mpls-mna-nrp-selector-01, 25 June 2024,
<https://datatracker.ietf.org/doc/html/draft-li-mpls-mna-
nrp-selector-01>.
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[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>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[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>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
[RFC9543] Farrel, A., Ed., Drake, J., Ed., Rokui, R., Homma, S.,
Makhijani, K., Contreras, L., and J. Tantsura, "A
Framework for Network Slices in Networks Built from IETF
Technologies", RFC 9543, DOI 10.17487/RFC9543, March 2024,
<https://www.rfc-editor.org/info/rfc9543>.
[RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and
Traffic Engineering Information Using BGP", RFC 9552,
DOI 10.17487/RFC9552, December 2023,
<https://www.rfc-editor.org/info/rfc9552>.
Authors' Addresses
Ran Chen
ZTE Corporation
Nanjing
China
Email: chen.ran@zte.com.cn
Jie Dong
Huawei
Beijing
China
Email: jie.dong@huawei.com
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Detao Zhao
ZTE Corporation
Nanjing
China
Email: zhao.detao@zte.com.cn
Liyan Gong
China mobile
Beijing
China
Email: gongliyan@chinamobile.com
Yongqing Zhu
China Telecom
Guangzhou
China
Email: zhuyq8@chinatelecom.cn
Ran Pang
China Unicom
Beijing
China
Email: pangran@chinaunicom.cn
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