Internet DRAFT - draft-zhang-sr-policy-enhanced-detnet
draft-zhang-sr-policy-enhanced-detnet
Network Working Group L. Zhang
Internet-Draft X. Geng
Intended status: Standards Track Z. Li
Expires: 14 September 2023 Huawei
13 March 2023
SR Policy for enhanced DetNet
draft-zhang-sr-policy-enhanced-detnet-01
Abstract
SR Policy is a set of candidate SR paths consisting of one or more
segment lists and necessary path attributes. It enables
instantiation of an ordered list of segments with a specific intent
for traffic steering. DetNet provides the capability to carry
specified unicast or multicast data flows with extremely low data
loss rates and bounded end-to-end latency within a network domain.
This document defines the SR policy enhancement to carry the Bounded
Latency Information with a candidate path of SR policy. So that BLI
behavior can be enabled automatically when the SR Policy is applied.
Requirements Language
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].
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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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 14 September 2023.
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Copyright Notice
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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
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 3
2.1. Requirement Language . . . . . . . . . . . . . . . . . . 3
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. BLI Encoding in SR Policy . . . . . . . . . . . . . . . . . . 3
3.1. BLI List Sub-TLV . . . . . . . . . . . . . . . . . . . . 3
3.2. Shared BLI sub-TLV . . . . . . . . . . . . . . . . . . . 5
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Segment Routing Policy is defined
in[I-D.ietf-spring-segment-routing-policy]. A SR Policy is a set of
candidate path which consist of one or more segment lists. The
headend node instructs the source routing and writes it into package.
The packets steered into an SR Policy have an ordered list of
segments associated with that SR Policy written into them.[RFC8655]
provides the overall architecture for Deterministic Networking
(DetNet), which provides the capability to carry specified unicast or
multicast data flows with extremely low data loss rates and bounded
end-to-end latency within a network domain. Based on
this,[I-D.ietf-detnet-bounded-latency] proposed a timing model for
sources, destinations, and DetNet transit nodes. Using the model, it
provides a methodology to compute end-to-end latency and backlog
bounds for various queuing
methods.[I-D.yzz-detnet-enhanced-data-plane] enhances the DetNet data
plane by introducing Bounded Latency Information (BLI) which
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facilitates DetNet transit nodes to guarantee the bounded latency
transmission in data plane. Based on
that,[I-D.geng-spring-sr-enhanced-detnet] defines how to leverage
Segment Routing (SR) and Segment Routing over IPv6 (SRv6) to
implement bounded latency. For An automatic network, the SR Policy
with Bounded Latency Information can facilitate the bounded latency
transmission and enable the automation of SR service.
This document defines the SR policy enhancement to carry the Bounded
Latency Information with a candidate path of SR policy. So that BLI
behavior can be enabled automatically when the SR Policy is applied.
2. Terminology and Conventions
2.1. Requirement 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[RFC2119].
2.2. Terminology
The abbreviations used in this document are:
BLI: Bounded Latency Information
SR: Segment Routing
SID: Segment Identifier
3. BLI Encoding in SR Policy
The BLI is proposed by[I-D.yzz-detnet-enhanced-data-plane] to
facilitate DetNet transit nodes to guarantee the bounded latency
transmission in data plane. In order to specify the bounded latency
features that the candidate path is associated with, this document
defines two types of new sub-TLV in the BGP Tunnel Encapsulation
Attribute for SR Policy[I-D.ietf-spring-segment-routing-policy] for
different scenarios.
3.1. BLI List Sub-TLV
When all of the nodes/adjacencies in the explicit path indicated by
the segment list request different BLI to guarantee bounded latency,
a BLI list sub-TLV is defined.
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The BLI list sub-TLV is formatted as follows.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BLI List [m] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BLI List [1] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
Type: to be assigned by IANA.
Length: 16 bits length value to indicate the length of BLI list in
octet.
BLI List [1… m]: 64 bits length BLI structure, representing the nth
BLI in the BLI list.
The BLI in the BLI List corresponds to the Segment in the Segment
List one by one. The length of the BLI List depends on the num of
Segment in the Segment List.
The encoding structure of BGP SR Policy with the BLI list sub-TLV is
expressed as below:
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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)
Segment List
BLI List
Weight
Segment
Segment
...
...
3.2. Shared BLI sub-TLV
When all of the nodes/adjacencies in the explicit path indicated by
the segment list request BLI to guarantee bounded latency with the
same BLI value, the Shared BLI sub-TLV is defined.
The Shared BLI sub-TLV is defined as follows:
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 (TBD2) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BLI |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
Type: to be assigned by IANA.
Length: 16 bits value indicate the length of BLI.
BLI: 64 bits value of Bounded Latency Information to guarantee the
bounded latency, the format of it is defined in section 3.1.
The encoding structure of BGP SR Policy with the Per-segment BLI sub-
TLV is expressed as below:
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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)
Segment List
Shared BLI
Weight
Segment
Segment
...
...
4. Procedures
When a candidate path of SR Policy is a bounded-latency routing path,
the originating node of SR policy MUST include the associated bounded
latency information in the BGP Tunnel Encapsulation Attribute of the
BGP SR Policy. The 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 a bounded-
latency path, the receiver node of the SR Policy MUST encapsulate the
specific bounded latency information to the header of packets steered
to the SR Policy. For SR Policy with IPv6 data plane and MPLS data
plane, the possible approach is to encapsulate the BLI to the packet
using the mechanism defined in[I-D.yzz-detnet-enhanced-data-plane]
and[I-D.geng-spring-sr-enhanced-detnet].
5. IANA Considerations
IANA is requested to make the assignment from the "BGP Tunnel
Encapsulation Attribute sub-TLVs" registry as follows.
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+-----------------+---------------------------------+----------------+
| Value | Name | Reference |
+-----------------+---------------------------------+----------------+
| TBD1 | BLI List sub-TLV | This document |
+-----------------+---------------------------------+----------------+
| TBD2 | Shared BLI sub-TLV | This document |
+-----------------+---------------------------------+----------------+
6. Security Considerations
TBD
7. Acknowledgements
8. Normative References
[I-D.geng-spring-sr-enhanced-detnet]
Geng, X., Li, Z., and T. Zhou, "Segment Routing for
Enhanced DetNet", Work in Progress, Internet-Draft, draft-
geng-spring-sr-enhanced-detnet-00, 11 July 2022,
<https://datatracker.ietf.org/doc/html/draft-geng-spring-
sr-enhanced-detnet-00>.
[I-D.ietf-detnet-bounded-latency]
Finn, N., Le Boudec, J., Mohammadpour, E., Zhang, J., and
B. Varga, "Deterministic Networking (DetNet) Bounded
Latency", Work in Progress, Internet-Draft, draft-ietf-
detnet-bounded-latency-10, 8 April 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
bounded-latency-10>.
[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-
ietf-idr-segment-routing-te-policy-20, 27 July 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
segment-routing-te-policy-20>.
[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-22, 22 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
segment-routing-policy-22>.
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[I-D.yzz-detnet-enhanced-data-plane]
Geng, X., Zhou, T., Zhang, L., and Z. Du, "DetNet Enhanced
Data Plane", Work in Progress, Internet-Draft, draft-yzz-
detnet-enhanced-data-plane-02, 24 December 2022,
<https://datatracker.ietf.org/doc/html/draft-yzz-detnet-
enhanced-data-plane-02>.
[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>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
Authors' Addresses
Li Zhang
Huawei
Email: zhangli344@huawei.com
Xuesong Geng
Huawei
Email: gengxuesong@huawei.com
Zhenbin Li
Huawei
Email: lizhenbin@huawei.com
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