Internet DRAFT - draft-li-cats-application-aware-computing-network
draft-li-cats-application-aware-computing-network
CATS Z. Li
Internet-Draft H. Shi
Intended status: Standards Track X. Chen
Expires: 1 September 2024 Huawei
Z. Du
China Mobile
S. Zhang
China Unicom
29 February 2024
Application Aware Computing Network
draft-li-cats-application-aware-computing-network-01
Abstract
This document describes a solution framework that adheres to the CATS
framework. The solution uses APN as part of the CATS service
identifier and flow identifier.
Status of This Memo
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This Internet-Draft will expire on 1 September 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Locator and APN ID . . . . . . . . . . . . . . . . . . . . . 3
3.1. APN Segment . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. LOC + APN ID . . . . . . . . . . . . . . . . . . . . . . 4
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Realization of CATS Framework Components . . . . . . . . 5
4.2. Realization of CATS Framework Workflow . . . . . . . . . 5
4.2.1. Service Announcement . . . . . . . . . . . . . . . . 5
4.2.2. Metric Distribution . . . . . . . . . . . . . . . . . 5
4.2.3. Service Request Processing . . . . . . . . . . . . . 5
4.2.4. Service Instance Affinity . . . . . . . . . . . . . . 6
5. APN for Real Locator . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Many services deploy their service instances in multiple
geographically distributed sites to get better response time. As
described in [I-D.ietf-cats-usecases-requirements], traffic steering
that takes into account both the computing resource metric and
network metric would improve the QoE of several services, e.g., AR/VR
and intelligent transportation.
A CATS framework is described in [I-D.draft-ldbc-cats-framework]. It
defines following core concepts:
1. CATS service identifier represents a service which consists of
multiple service contact instances.
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2. Service contact instance affinity means that packet that belongs
to a flow should always goes to the same service contact
instance.
These concepts are similar to APN described in
[I-D.draft-li-apn-header]. The Application-aware Networking (APN)
framework[I-D.li-apn-framework] defines that application-aware
information (i.e. APN attribute) including APN identification (ID)
and/or APN parameters (e.g. network performance requirements) is
encapsulated at network edge devices and carried in packets
traversing an APN domain in order to facilitate service provisioning,
perform fine-granularity traffic steering and network resource
adjustment. [I-D.li-apn-app-side-framework] defines the extension of
the APN framework for the application side. In this extension, the
APN resources of an APN domain is allocated to applications which
compose and encapsulate the APN attribute in packets. The APN ID
includes application group ID and user group ID. Application group
ID can be used as part of CATS service identifier. User group ID +
application group ID can be used as CATS flow ID. This document
describes a CATS framework using APN. The realization can use APN
framework for application side.
2. Terminology
This document reuses terms defined in [I-D.draft-ldbc-cats-framework]
and [I-D.draft-li-apn-header].
2.1. 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.
3. Locator and APN ID
In CATS, the packet needs to carry the locator information and the
application identifier information. The application identifier
information can be carried in APN ID. As described in
[I-D.draft-li-apn-header], the length of the APN ID can be 32bit, 64
bit or 128bit. Depending on whether APN ID can fit into 128bit, the
following two formats are defined. They carry the same information
and can be used in different deployment scenarios.
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3.1. APN Segment
APN segment is an SRv6 SID[RFC8986], consisting of LOC:FUNCT:ARG,
where:
* LOC is routable and leads to the service contact instance.
* FUNCT is APN ID which consists of user group id and application
group ID. The length of APN ID is 32 bit or 64 bit.
3.2. LOC + APN ID
If 128 bit is not enough to hold the APN ID + LOC. Then the APN ID
can be put in other places as described in
[I-D.draft-li-apn-ipv6-encap], e.g., IPv6 extension header.
4. Overview
For simplicity, this document use APN segment as an illustration
example, see Figure 1.
APN Seg: APN segment = LOC:FUNCT(APN ID): ARG
APN Seg
+-------------+ +----------+
|CATS-Router 1| | Service |
+-------------+-------| contact |
CATS Forwarding Table | C-SMA | | instance |
LOC+APP ID, metrics, To CATS-Router1 +-------------+ +----------+
LOC+APP ID, metrics, To CATS-Router3 |
+-------------+ +----------------+
| C-TC | | |
+------+ |-------------| | Underlay |
|Client|-----| | C-PS |--------| Infrastructure |
+------+ | +-------| | |
|CATS-Router 2| | |
+-------------+ +----------------+
CATS Flow Table | APN Seg
LOC+APN ID, To CATS-Router1 +-------------+ +----------+
|CATS-Router 3| | Service |
+-------------+-------| contact |
| C-SMA | | instance |
+-------------+ +----------+
<---------------------- <----------------
(Overlay route of APN Seg, metrics) (APN Seg, metrics)
Service overlay route w/ metrics Service route w/ metrics
Figure 1: Architecture Overview
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4.1. Realization of CATS Framework Components
The LOC + application group ID in the APN segment is used as CATS
service identifier. The CATS overlay is established from the Ingress
CATS-Router to an Egress CATS-Router. The CATS Traffic Classifier is
running at the Ingress CATS-Router. Depending on the deployment, the
CATS Path Selector, C-SMA and C-NMA can be centralized or
distributed. CIS-ID is used to forward the packet to a specific CATS
service contact instance. The choice of the CIS-ID is out of scope.
4.2. Realization of CATS Framework Workflow
4.2.1. Service Announcement
Locator is routable and leads to service contact instances. The
locator is announced in anycast. The locator and application group
ID may be learned by client using a rendezvous service (DNS, for
example). The user group ID may be learned through a protocol
between the client and server. The detailed rendezvous procedure is
out of scope.
4.2.2. Metric Distribution
As described in CATS framework, the metrics needs to be distributed
along with the CS-ID route. The detailed control plane solution
depends on the deployment model (distributed, centralized or hybrid)
and is out of scope of this document. A sample procedure using
distributed model is provided to illustrate the core process, see
Figure 1.
The C-SMA running as stand alone component at each service contact
instance. In addition to the route announcement of LOC, C-SMA also
distributes the application group ID and the computing metric to the
Egress. The egress then pass the [(LOC, application group ID),
computing metric] to the ingress node. The protocol extension used
to carry the information is out of scope.
4.2.3. Service Request Processing
The service request packet has the destination address set to APN
segment. The C-TC component in Ingress uses LOC + application group
ID to match the service, finding the optimal service contact
instance. Then the best path to the corresponding service instance
is selected by C-PS. The packet is encapsulated and forwarded using
the overlay path. The Egress decapsulates the packet then forward it
to the service contact instance.
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4.2.4. Service Instance Affinity
As per [I-D.draft-ldbc-cats-framework], the packets belong to the
same flow should goes to the same service contact instance. This
document defines flow identifier as the tuple (locator, user group
ID, app group ID). By assigning the user group ID and app group ID,
the service can archive customizable flow affinity without relying on
traditional (IP, port) tuple.
5. APN for Real Locator
[I-D.draft-shi-cats-with-real-locator] defines real locator for CATS.
When implementing solution of APN for CATS, the real locator can be
carried in APN Para. Other procedure is the same as defined in
[I-D.draft-shi-cats-with-real-locator].
6. Security Considerations
This document does not introduce any new security considerations.
7. IANA Considerations
TBD.
8. References
8.1. Normative References
[I-D.draft-li-apn-header]
Li, Z., Peng, S., and S. Zhang, "Application-aware
Networking (APN) Header", Work in Progress, Internet-
Draft, draft-li-apn-header-04, 12 April 2023,
<https://datatracker.ietf.org/doc/html/draft-li-apn-
header-04>.
[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/rfc/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/rfc/rfc8174>.
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[I-D.draft-li-apn-ipv6-encap]
Li, Z., Peng, S., and C. Xie, "Application-aware IPv6
Networking (APN6) Encapsulation", Work in Progress,
Internet-Draft, draft-li-apn-ipv6-encap-07, 10 July 2023,
<https://datatracker.ietf.org/doc/html/draft-li-apn-ipv6-
encap-07>.
[I-D.draft-shi-cats-with-real-locator]
Shi, H., Chen, X., and Z. Li, "CATS based on Real
Locator", Work in Progress, Internet-Draft, draft-shi-
cats-with-real-locator-00, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-shi-cats-
with-real-locator-00>.
8.2. Informative References
[I-D.ietf-cats-usecases-requirements]
Yao, K., Trossen, D., Boucadair, M., Contreras, L. M.,
Shi, H., Li, Y., Zhang, S., and Q. An, "Computing-Aware
Traffic Steering (CATS) Problem Statement, Use Cases, and
Requirements", Work in Progress, Internet-Draft, draft-
ietf-cats-usecases-requirements-02, 1 January 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-cats-
usecases-requirements-02>.
[I-D.draft-ldbc-cats-framework]
Li, C., Du, Z., Boucadair, M., Contreras, L. M., and J.
Drake, "A Framework for Computing-Aware Traffic Steering
(CATS)", Work in Progress, Internet-Draft, draft-ldbc-
cats-framework-06, 8 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ldbc-cats-
framework-06>.
Authors' Addresses
Zhenbin Li
Huawei
Beijing
Email: lizhenbin@huawei.com
Hang Shi
Huawei
Beiqing Road
Beijing
China
Email: shihang9@huawei.com
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Xia Chen
Huawei
Beijing
China
Email: jescia.chenxia@huawei.com
Zongpeng Du
China Mobile
Beijing
China
Email: duzongpeng@foxmail.com
Shuai Zhang
China Unicom
Beijing
China
Email: zhangs366@chinaunicom.cn
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