Internet DRAFT - draft-yi-idr-bgp-fs-edge-service-metadata
draft-yi-idr-bgp-fs-edge-service-metadata
IDR X. Yi, Ed.
Internet-Draft T. He, Ed.
Intended status: Standards Track China Unicom
Expires: 21 February 2024 H. Shi, Ed.
X. Ding
H. Wang
Huawei Technologies
Z. Wang
Inspur
20 August 2023
Distribution of Service Metadata in BGP FlowSpec
draft-yi-idr-bgp-fs-edge-service-metadata-01
Abstract
In edge computing, a service may be deployed on multiple instances
within one or more sites, called edge service. The edge service is
associated with an ANYCAST IP address, and the route of it along with
service metadata can be collected by a central controller. The
controller may process the metadata and distribute the result to
ingress routers using BGP FlowSpec. The service metadata can be used
by ingress routers to make path selections not only based on the
routing cost but also the running environment of the edge services.
This document describes a mechanism to distribute the information of
the service routes and related service metadata using BGP FlowSpec.
Status of This Memo
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This Internet-Draft will expire on 21 February 2024.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. BGP FlowSpec Extension for Service Metadata . . . . . . . . . 3
2.1. Metadata Path Attribute TLV . . . . . . . . . . . . . . . 4
2.2. Aggregated Metric Path Attribute TLV . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Many modern services deploy their service instances in multiple sites
to get better response time and resource utilization. These sites
are often geographically distributed to serve the user demand. For
some services such as VR/AR and intelligent transportation, the QoE
will depend on both the network metrics and the compute metrics. For
example, if the nearest site is overloaded due to the demand
fluctuation, then steer the user traffic to another light-loaded
sites may improve the QoE. To steer the traffic to the best site,
the computing metadata of the site needs to be collected.
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[I-D.ietf-idr-5g-edge-service-metadata] describes the BGP extension
of distributing service route with network and computing-related
metrics. The router connected to the site will received the service
routes and service metadata sent from devices inside the edge site,
and then generates the corresponding routes and distributes them to
ingress routers. However, the route with service metadata on the
router connected to the site can be also collected by a central
controller using BGP LS. Then the central controller may process the
metadata and distributes the result to the ingress router using BGP
FlowSpec.
This document defines an extension of BGP FlowSpec to carry the
service metadata along with the service route which is received from
the controller. Using the service metadata and the service route,
the ingress router can calculate the best site for the traffic,
giving each user the best QoE.
1.1. Terminology
1.2. 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. BGP FlowSpec Extension for Service Metadata
The goal of the BGP FlowSpec extension is to distribute the
information of the service route and metadata. A service is
identified by an prefix and this information is carried using the
existing Destination Prefix Component specified in [RFC8955] and
[RFC8956]. [I-D.ietf-idr-ts-flowspec-srv6-policy] defines that the
Color Extended Community and BGP Prefix-SID attribute is carried in
the context of the FlowSpec NLRI.
In addition to that, this document proposes to carry the service
metadata attribute(See Figure 1). The ingress router can compare the
compute metric of different sites and steer the traffic into the best
one using the SR policy. The metadata can be original values defined
in [I-D.ietf-idr-5g-edge-service-metadata] or an aggregated one
calculated using original values.
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+------------+
| BGP FS |
| Controller |
+------------+
| FlowSpec route to Ingress:
| NLRI: Destination Prefix
| Redirect to IPv6 Nexthop: Egress's Address
| Policy Color: C1
| PrefixSID: End.X1
| Service Metadata: Compute metric
| .-----.
| ( )
V .--( )--.
+-------+ ( ) +------+ +---------+
| |_( SRv6 Core Network )_| | (End.X1) | |
|Ingress| ( ================> ) |Egress|----------| Site |
+-------+ (SR List<S1,S2,S3>) +------+ +---------+
'--( )--'
( )
'-----'
Figure 1: Example of using BGP FlowSpec to distribute the service
route and metadata
2.1. Metadata Path Attribute TLV
The Metadata Path Attribute TLV is the same as defined in
[I-D.ietf-idr-5g-edge-service-metadata], including the following
three sub-TLVs:
1. Site Preference Index sub-TLV indicates the preference to choose
the site.
2. Capacity Index sub-TLV indicates the capability of a site. One
Edge Site can be in full capacity, reduced capacity, or
completely out of service.
3. Load Measurement sub-TLV indicates the load level of the site.
2.2. Aggregated Metric Path Attribute TLV
The Aggregated Metric Path Attribute is a newly defined TLV(See
Figure 2). It contains a single aggregated value which is calculated
by the controller using the original metrics such as site preference,
capacity and load measurement.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Aggregated Metadata Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Aggregated Metric Value (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Aggregated Metric Path Attribute TLV format
* Type: identify the Aggregated Metadata Attribute, to be assigned
by IANA.
* Length: the total number of the octets of the value field.
* Value: value of Aggregated Computing metric.
3. Security Considerations
TBD
4. IANA Considerations
This document requires IANA to assign the following code points from
the registry called "BGP Path Attributes":
+=======+==========================+=============+
| Value | Description | Reference |
+=======+==========================+=============+
| TBD1 | Aggregated Metadata Type | Section 2.2 |
+-------+--------------------------+-------------+
Table 1
5. Normative References
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/info/rfc8956>.
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[I-D.ietf-idr-5g-edge-service-metadata]
Dunbar, L., Majumdar, K., Wang, H., and G. S. Mishra, "BGP
Extension for 5G Edge Service Metadata", Work in Progress,
Internet-Draft, draft-ietf-idr-5g-edge-service-metadata-
07, 2 December 2022, <https://www.ietf.org/archive/id/
draft-ietf-idr-5g-edge-service-metadata-00.txt>.
[I-D.ietf-idr-ts-flowspec-srv6-policy]
Wenying, J., Liu, Y., Zhuang, S., Mishra, G. S., and S.
Chen, "Traffic Steering using BGP FlowSpec with SRv6
Policy", Work in Progress, Internet-Draft, draft-ietf-idr-
ts-flowspec-srv6-policy-01, 9 October 2022,
<https://www.ietf.org/archive/id/draft-ietf-idr-ts-
flowspec-srv6-policy-01.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>.
[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>.
Authors' Addresses
Xinxin Yi (editor)
China Unicom
Beijing
China
Email: yixx3@chinaunicom.cn
Tao He (editor)
China Unicom
Beijing
China
Email: het21@chinaunicom.cn
Hang Shi (editor)
Huawei Technologies
Beijing
China
Email: shihang9@huawei.com
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Xiangfeng Ding
Huawei Technologies
Beijing
China
Email: dingxiangfeng@huawei.com
Haibo Wang
Huawei Technologies
Beijing
China
Email: rainsword.wang@huawei.com
Zicheng Wang
Inspur
Beijing
China
Email: wangzicheng01@inspur.com
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