BGP SR Policy Extensions for Network Resource Partition
draft-dong-idr-sr-policy-nrp-00
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Jie Dong , Zhibo Hu, Ran Pang | ||
| Last updated | 2022-03-03 | ||
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draft-dong-idr-sr-policy-nrp-00
IDR Working Group J. Dong
Internet-Draft Z. Hu
Intended status: Standards Track Huawei Technologies
Expires: 5 September 2022 R. Pang
China Unicom
4 March 2022
BGP SR Policy Extensions for Network Resource Partition
draft-dong-idr-sr-policy-nrp-00
Abstract
Segment Routing (SR) Policy is a set of candidate paths, each
consisting of one or more segment lists and the associated
information. The header of a packet steered in an SR Policy is
augmented with an ordered list of segments associated with that SR
Policy. A Network Resource Partition (NRP) is a set of network
resources allocated in the network which can be used to instantiate a
virtual transport network (VTN) for one or a group service traffic.
In scenarios where multiple Network Resource Partitions (NRPs) exist
in the network, the NRP in which an SR policy is instantiated may
also need to be specified, so that the header of the packet can be
augmented with the information associated with the NRP. An SR Policy
candidate path can be distributed using BGP SR Policy. This document
defines extensions to BGP SR policy to specify the NRP in which the
SR policy is instantiated.
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
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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 5 September 2022.
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Copyright Notice
Copyright (c) 2022 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
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. NRP Identifier of SR Policy . . . . . . . . . . . . . . . . . 3
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The concept of Segment Routing (SR) policy is defined in
[I-D.ietf-spring-segment-routing-policy]. An SR Policy is a set of
candidate paths, each consisting of one or more segment lists. The
head end of an SR Policy may learn multiple candidate paths for an SR
Policy. The header of a packet steered in an SR Policy is augmented
with an ordered list of segments associated with that SR Policy. The
BGP extensions to distribute SR Policy candidate paths is defined in
[I-D.ietf-idr-segment-routing-te-policy].
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, multiple 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
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to instantiate a VTN for one or a group of IETF network slice
services. As described in [I-D.dong-teas-nrp-scalability], one
scalable data plane approach is to carry a global 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 network resources allocated
to the NRP.
In networks where multiple NRPs exist, the identifier of NRP in which
the SR policy is instantiated need to be specified, so that at the
ingress node of SR policy, the header of data packet can also be
augmented with the identifier of the NRP. This document defines the
BGP extensions to specify the NRP ID associated with a candidate path
of SR policy.
2. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. NRP Identifier of SR Policy
In order to specify the NRP the candidate path of SR policy is
associated with, a new sub-TLV called "NRP sub-TLV" is defined in the
BGP Tunnel Encapsulation Attribute [RFC9012]. The NRP sub-TLV can be
carried in the BGP Tunnel Encapsulation Attribute with the tunnel
type set to SR Policy.
The NRP sub-TLV is optional and MUST NOT appear more than once for
one SR Policy candidate path. If the NRP sub-TLV appears more than
once, the associated BGP SR Policy NLRI is considered malformed and
the "treat-as-withdraw" strategy of [RFC7606] is applied.
The NRP sub-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) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1. NRP Sub-TLV
where:
* Type: 123
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* Length: 6
* Flags: 1-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: 1 octet of reserved bits. It SHOULD be set to zero on
transmission and MUST be ignored on receipt.
* NRP ID: A 32-bit global significant identifier which is used to
identify a NRP. Value 0 and 0xFFFFFFFF are reserved.
The encoding structure of BGP SR Policy with the NRP sub-TLV is
expressed as below:
SR Policy SAFI NLRI: <Distinguisher, Policy-Color, Endpoint>
Attributes:
Tunnel Encaps Attribute (23)
Tunnel Type: SR Policy
Binding SID
Preference
Priority
Policy Name
Explicit NULL Label Policy (ENLP)
NRP
Segment List
Weight
Segment
Segment
...
...
4. Procedures
When a candidate path of SR policy is instantiated with a specific
NRP, the originating node of SR policy SHOULD include the NRP ID in
the BGP Tunnel Encapsulation Attribute of the BGP SR policy. The
setting of other fields and attributes in BGP SR policy SHOULD
follows the mechanism as defined in
[I-D.ietf-idr-segment-routing-te-policy].
When a BGP speaker receives an SR Policy which is acceptable and
usable according to the rules as defined in
[I-D.ietf-idr-segment-routing-te-policy], and the SR Policy candidate
path selected as the best candidate path is associated with an NRP,
the receiver node of the SR policy SHOULD encapsulate the NRP ID in
the header of packets steered to the SR Policy. For SR Policy with
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IPv6 data plane, the approach is to encapsulate the NRP ID in IPv6
Hop-by-Hop extension header using the mechanism as defined in
[I-D.dong-6man-enhanced-vpn-vtn-id]. For SR Policy with MPLS data
plane, one possible mechanism to encapsulate the NRP ID to the packet
is defined in [I-D.li-mpls-enhanced-vpn-vtn-id].
Although the proposed mechanism allows that different candidate paths
in one SR policy be associated with different NRPs, in normal network
scenarios it is considered that the association between an SR Policy
and NRP is consistent, in such case all candidate paths of one SR
policy SHOULD be associated with the same NRP.
5. Security Considerations
The security considerations of BGP and BGP SR policy apply to this
document.
6. IANA Considerations
IANA has assigned the sub-TLV type as defined in Section 3 from "BGP
Tunnel Encapsulation Attribute sub-TLVs" registry.
Value Description Reference
----------------------------------------------------
123 NRP This document
7. Acknowledgments
The authors would like to thank Guoqi Xu, Lei Bao and Haibo Wang for
the review and discussion of this document.
8. References
8.1. Normative References
[I-D.dong-teas-nrp-scalability]
Dong, J., Li, Z., Gong, L., Yang, G., Guichard, J. N.,
Mishra, G., Qin, F., Saad, T., and V. P. Beeram,
"Scalability Considerations for Network Resource
Partition", Work in Progress, Internet-Draft, draft-dong-
teas-nrp-scalability-01, 7 February 2022,
<https://www.ietf.org/archive/id/draft-dong-teas-nrp-
scalability-01.txt>.
[I-D.ietf-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
Jain, D., and S. Lin, "Advertising Segment Routing
Policies in BGP", Work in Progress, Internet-Draft, draft-
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ietf-idr-segment-routing-te-policy-14, 10 November 2021,
<https://www.ietf.org/archive/id/draft-ietf-idr-segment-
routing-te-policy-14.txt>.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", Work in
Progress, Internet-Draft, draft-ietf-spring-segment-
routing-policy-18, 17 February 2022,
<https://www.ietf.org/archive/id/draft-ietf-spring-
segment-routing-policy-18.txt>.
[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+)
Services", Work in Progress, Internet-Draft, draft-ietf-
teas-enhanced-vpn-09, 25 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-teas-enhanced-
vpn-09.txt>.
[I-D.ietf-teas-ietf-network-slices]
Farrel, A., Gray, E., Drake, J., Rokui, R., Homma, S.,
Makhijani, K., Contreras, L. M., and J. Tantsura,
"Framework for IETF Network Slices", Work in Progress,
Internet-Draft, draft-ietf-teas-ietf-network-slices-05, 25
October 2021, <https://www.ietf.org/archive/id/draft-ietf-
teas-ietf-network-slices-05.txt>.
[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>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<https://www.rfc-editor.org/info/rfc7606>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
8.2. Informative References
[I-D.dong-6man-enhanced-vpn-vtn-id]
Dong, J., Li, Z., Xie, C., Ma, C., and G. Mishra,
"Carrying Virtual Transport Network (VTN) Identifier in
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IPv6 Extension Header", Work in Progress, Internet-Draft,
draft-dong-6man-enhanced-vpn-vtn-id-06, 24 October 2021,
<https://www.ietf.org/archive/id/draft-dong-6man-enhanced-
vpn-vtn-id-06.txt>.
[I-D.li-mpls-enhanced-vpn-vtn-id]
Li, Z. and J. Dong, "Carrying Virtual Transport Network
Identifier in MPLS Packet", Work in Progress, Internet-
Draft, draft-li-mpls-enhanced-vpn-vtn-id-01, 14 April
2021, <https://www.ietf.org/archive/id/draft-li-mpls-
enhanced-vpn-vtn-id-01.txt>.
Authors' Addresses
Jie Dong
Huawei Technologies
Email: jie.dong@huawei.com
Zhibo Hu
Huawei Technologies
Email: huzhibo@huawei.com
Ran Pang
China Unicom
Email: pangran@chinaunicom.cn
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