Internet DRAFT - draft-hwy-opsawg-ifl-framework
draft-hwy-opsawg-ifl-framework
OPSAWG Working Group L. Han
Internet-Draft M. Wang
Intended status: Informational China Mobile
Expires: 27 June 2023 F. Yang
T. Zhou
Huawei
24 December 2022
Inband Flow Learning Framework
draft-hwy-opsawg-ifl-framework-02
Abstract
To deploy the inband performance measurement and flow information
telemetry on live traffic, this document proposes a framework of an
inband and flow based flow information learning mechanism called
Inband Flow Learning (IFL). This document also provides different
deployment approaches and considerations in practical network
deployment.
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.
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
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 27 June 2023.
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Copyright Notice
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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. Framework of Inband Flow Learning . . . . . . . . . . . . . . 3
3.1. Service Discovery . . . . . . . . . . . . . . . . . . . . 4
3.2. Inband Flow Information Telemetry Deployment . . . . . . 4
3.2.1. Telemetry Mode . . . . . . . . . . . . . . . . . . . 4
3.2.2. Telemetry Policy . . . . . . . . . . . . . . . . . . 6
3.2.3. Telemetry Instance . . . . . . . . . . . . . . . . . 6
4. Inband Flow Information Telemetry Adjustment . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Network telemetry [RFC9232] is a technology for gaining network
insight by applying means of network data generation, data
collection, data correlation, and data consumption. It provides the
network visibility to the state and behavior of a network, which is
crucial for network operation and network load supervision. From
operator's perspective, it is important to monitor live traffic
running in the network, including the bandwidth occupied by the
traffic, traffic delay, traffic jitter and traffic packet loss.
Under this circumstance, inband performance measurement
[I-D.ietf-mpls-inband-pm-encapsulation] [I-D.ietf-6man-ipv6-alt-mark]
and inband flow information telemetry
[I-D.song-opsawg-ifit-framework] work complementary to provide the
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network traffic supervision.
To deploy the inband performance measurement and flow information
telemetry on live traffic, this document proposes a framework of an
inband and flow based flow information learning mechanism called
Inband Flow Learning (IFL). This document also provides different
deployment approaches and considerations in practical network
deployment. Note that this document focuses on generating telemetry
data object based on inband performance measurement of data packet.
Telemetry based on means other than inband performance measurement of
data packet is not within the scope of this document.
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.2. Terminology
IFL: Inband Flow Learning
IFITI: Inband Flow Information Telemetry Instance
3. Framework of Inband Flow Learning
The framework of Inband Flow Learning (IFL) includes three components
of Service Discovery, Inband Flow Information Telemetry Deployment
and Inband Flow Information Telemetry Adjustment shown in Figure 1.
+---------+---------------------+--------------------+--------------------+
|Component| Service | Inband Flow | Inband Flow |
| | Discovery | Information | Information |
| | |Telemetry Deployment|Telemetry Adjustment|
+---------+---------------------+--------------------+--------------------+
|Functions| Sampling policy | Telemetry policy | |
| |---------------------+--------------------+ Aging |
| | Flow characteristic | Telemetry instance | |
| | acquisition | | |
+---------+---------------------+--------------------+--------------------+
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Figure 1 Framework of Inband Flow Learning
3.1. Service Discovery
Before starting the telemetry on service flows, the service should be
discovered. Service discovery is a process of sampling to the
service flow which is being transmitted in network in order to
further determine which flow should be monitored. The target of
service discovery function is to obtain the flow characteristics.
The characteristics of flows are represented in terms of IP source
address, IP destination address, TCP/UDP port number, VRF, incoming/
outgoing interface etc.
The flow characteristics are automatically obtained from the sampling
of live traffics in data plane. It creates the data base of flow
characteristics can further be used to generate flow telemetry. The
network node discovers the flow characteristic from the obtained
service live traffic and sends them to the network controller server,
if the characteristics are not included in the characteristic
information base. The rules of the sampling to the flows are called
sampling policy. For example, a specific priority value of IP packet
can be a rule of a sampling policy. Sampling policy can be pre-
configured from control and management planes via various protocols,
e.g. NETCONF. Network controller also sends policies for the
service discovery before the flow characteristics discovery. The
characteristic information extracting can be based on the policy, and
preset cycle etc.
3.2. Inband Flow Information Telemetry Deployment
After acquiring the traffic characteristics, telemetry based on the
inband flow information can be planned and deployed. There are two
modes to deploy inband flow information telemetry: End-to-End (E2E)
and Hop-by-Hop (HbH). To deploy the inband flow information
telemetry, the telemetry policy and the telemetry instance are also
defined in following subsections.
3.2.1. Telemetry Mode
For majority of the services, end-to-end telemetry of service flows
can meet the requirements from operators. In E2E mode shown in
Figure 2, ingress node discovers the traffic characteristics and
proceed on-path telemetry on device to report data to data consumer.
Ingress node may also encapsulate flow identifier to facilitate the
identification of flow information telemetry on egress node. Egress
node identifies the flow and alternate marking identifier, proceed
the record on packet number and timestamp, and further telemetry the
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statistics to data consumer. Transit node does not require any
detection of flow information or processing of telemetry.
+-------------+
|Data Consumer| compute E2E flow info
+-------------+
| |
___flow info__| |____flow info____
| telemetry telemetry |
| |
+---------+ +---------+ +---------+ +---------+
| Ingress |---| Transit | ...| Transit |---| Egress |
| Node | | Node | | Node | | Node |
+---------+ +---------+ +---------+ +---------+
Figure 2 End-to-End Telemetry Mode
The distinction of HbH mode to E2E mode is that transit node also
participates the inband flow information learning and telemetry. In
HbH mode shown in Figure 3, telemetry covers the flow information on
every node of the forwarding path the flow packet is transmitted,
which provides detailed flow information on each hop. Hop-by-Hop
telemetry usually works in the need of an on-demand fault diagnose.
+-------------+
|Data Consumer| compute HbH flow info
+-------------+
| | | | flow info telemetry
______________| | | |_________________
| ___| |___ |
| | | |
+---------+ +---------+ +---------+ +---------+
| Ingress |---| Transit | ...| Transit |---| Egress |
| Node | | Node | | Node | | Node |
+---------+ +---------+ +---------+ +---------+
Figure 3 Hop-by-Hop Telemetry Mode
The telemetry mode is also indicated by the service packet in data
plane to help the transit node to differentiate the needs of
telemetry.
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3.2.2. Telemetry Policy
Telemetry policy is used to determine which flow should be monitored.
By configuring telemetry policy, it can increase the priority of
learning and telemetry to critical flow and reduce or filter the
learning and telemetry of unimportant flows. It is crucial to
network deployment for two reasons, one is the number of flows can be
huge, another is the limitation of processing capability either on
the controller or the network node. There might be millions of flows
in a large scale network, for example 5G mobile backhaul network. It
is important to wisely choose the granularity of inband flow
information telemetry.
Regarding IP traffics, the telemetry policy can be based on either
one of or combination of flow characteristics, such as IP source/
destination address, TCP/UDP port number, VRFs, or network device
interfaces etc. An IP address with a flexible wildcard mask can also
be used as means to provide telemetry policy to an aggregation of
flows. Flow-ID Label Indicator
[I-D.ietf-mpls-inband-pm-encapsulation] or FlowMonID
[I-D.ietf-6man-ipv6-alt-mark] is also an alternative to identify the
telemetry policy at transit or egress nodes.
3.2.3. Telemetry Instance
Inband flow learning function manages the inband flow information
telemetry based on Inband Flow Information Telemetry Instance
(IFITI), in short called telemetry instance.
According to the flow characteristics, a telemetry instance for
monitoring the service flow is generated by the network control plane
in either distributed or centralized way. Ingress node can filter
the received flows based on the pre-defined telemetry policy and
create telemetry instance by itself. Network node can also obtain
the instance and the corresponding identifier such as Flow-ID,
encapsulate the identifier in the service flow to setup the
relationship between the characteristic information, telemetry
instance and the service flow, and perform telemetry.
Once the telemetry instance is created, ingress node can start the
telemetry of flow information based on the method of alternative
marking. At the same time, ingress node encodes inband monitoring
information for example the flow ID in the service packets. Transit
or egress node detect the inband monitoring information of packets
and automatically create telemetry instance to deploy the inband flow
information telemetry. The automatic creation of telemetry instance
on network node can greatly facilitate the dynamic and incremental
deployment.
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The controller can also initiate the creation of telemetry instance
and assign the telemetry instance to the ingress node to start the
telemetry.
If the service message related to certain characteristic information
is not received within the preset time, it is determined that the
characteristic information is in an invalid state. And send the
failure status information to the controller.
4. Inband Flow Information Telemetry Adjustment
If the service message related to certain characteristic information
is not received within the preset time, the characteristic
information is determined to come into an invalid state. Further the
failure status information is sent to the network controller.
When route convergence happens to the network, service flow may
switch to other forwarding nodes. When the traffic changes,
telemetry instance varies as well. Regarding the telemetry instance
running on the fault path, the aging of IFITI should be supported in
order to recycle the network resources. IFITI should be deleted once
it becomes stale. To monitor the same flow information, new
telemetry instance is required to add on the new transit or egress
node. Note that aging and adjustment of IFITI can be initiated by
controller or network node. When a specific timer used for flow
information telemetry timeout, the IFITI would be deleted to stop the
telemetry of the flow.
5. IANA Considerations
This document has no request to IANA
6. Security Considerations
TBD
7. References
7.1. Normative References
[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>.
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[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>.
7.2. Informative References
[I-D.hwyh-ippm-ps-inband-flow-learning]
Han, L., Wang, M., Yang, F., and J. Huang, "Problem
Statement and Requirement for Inband Flow Learning", Work
in Progress, Internet-Draft, draft-hwyh-ippm-ps-inband-
flow-learning-01, 25 October 2021,
<https://www.ietf.org/archive/id/draft-hwyh-ippm-ps-
inband-flow-learning-01.txt>.
[I-D.ietf-6man-ipv6-alt-mark]
Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R.
Pang, "IPv6 Application of the Alternate Marking Method",
Work in Progress, Internet-Draft, draft-ietf-6man-ipv6-
alt-mark-17, 27 September 2022,
<https://www.ietf.org/archive/id/draft-ietf-6man-ipv6-alt-
mark-17.txt>.
[I-D.ietf-mpls-inband-pm-encapsulation]
Cheng, W., Min, X., Zhou, T., Dong, X., and Y. Peleg,
"Encapsulation For MPLS Performance Measurement with
Alternate Marking Method", Work in Progress, Internet-
Draft, draft-ietf-mpls-inband-pm-encapsulation-03, 1 July
2022, <https://www.ietf.org/archive/id/draft-ietf-mpls-
inband-pm-encapsulation-03.txt>.
[I-D.song-opsawg-ifit-framework]
Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "A
Framework for In-situ Flow Information Telemetry", Work in
Progress, Internet-Draft, draft-song-opsawg-ifit-
framework-19, 24 October 2022,
<https://www.ietf.org/archive/id/draft-song-opsawg-ifit-
framework-19.txt>.
[RFC9232] Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and
A. Wang, "Network Telemetry Framework", RFC 9232,
DOI 10.17487/RFC9232, May 2022,
<https://www.rfc-editor.org/info/rfc9232>.
Authors' Addresses
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Liuyan Han
China Mobile
Beijing
China
Email: hanliuyan@chinamobile.com
Minxue Wang
China Mobile
Beijing
China
Email: wangminxue@chinamobile.com
Fan Yang
Huawei
Beijing
China
Email: shirley.yangfan@huawei.com
Tianran Zhou
Huawei
Beijing
China
Email: zhoutianran@huawei.com
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