Internet DRAFT - draft-quan-l4s-ioam
draft-quan-l4s-ioam
Network Working Group W. Quan
Internet-Draft W. Su
Intended status: Standards Track S. Pan
Expires: 4 September 2024 Beijing Jiaotong University
X. Liang
J. Liang
China Telecom
3 March 2024
IOAM network awareness for Low Latency, Low Loss, and Scalable
Throughput (L4S)
draft-quan-l4s-ioam-00
Abstract
This specification defines a framework how to update L4S Dual-Queue
Coupled AQM with In Situ Operations, Administration, and Maintenance
(IOAM). These are designed for consistently very low queuing
latency, very low congestion loss, and scaling of perflow throughput
by using Explicit Congestion Notification (ECN) using the operational
and telemetry information collected by IOAM. Since L4S lacks
information about the use of network status and network nodes, which
also affect network performance in practice, it is considered to use
direct export mode for information collection of L4S-IOAM to
strengthen the AQM regulation of L4S. It then gives the normative
requirements that are necessary.
Status of This Memo
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This Internet-Draft will expire on 4 September 2024.
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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
3. IOAM network awareness in L4S framework . . . . . . . . . . . 4
4. Information Details . . . . . . . . . . . . . . . . . . . . . 5
5. UseCases . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
The L4S architecture [RFC9330] allows routers to use a different
marking system that can provide early reaction to incipient
congestion [RFC9332] and defines a reaction for this feedback when
packets are marked with ECN. But congestion still occurs in front of
the L4S node. The application of IOAM technology in L4S framework
can effectively solve this problem. In Situ Operations,
Administration, and Maintenance (IOAM) is used for recording and
collecting operational and telemetry information while the packet
traverses a path between two points in the network. The IOAM data
fields are further updated in [RFC9326] for direct export use cases.
This document defines how to use the information collected by the
front-end nodes to better update the L4S mechanism. IOAM can collect
operational and telemetry information. L4S uses an Explicit
Congestion Notification (ECN) scheme at the IP layer with the same
set of codepoint transitions as the original (or 'Classic') ECN.
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The goal of L4S-IOAM is to solve the problem of how to get
information awareness between the IOAM network and the L4S site. The
basis to achieve this goal is network and computing. Therefore,
Network Information Awareness (NIA) system architecture is proposed.
As the control plane of the L4S-IOAM framework, NIA introduces the
control center component on top of the L4S-IOAM framework to realize
the management and comprehensive analysis of network information and
encourage L4S site to take action to consider local network
awareness.
This specification defines how the data collected by IOAM can be used
to better update the Low Latency, Low Loss, and Scalable throughput
(L4S). The terms "encapsulation" and "decapsulation" are used in
this document in the same way as [RFC9197]. An IOAM encapsulating
node incorporates one or more IOAM Option-Types into packets that
IOAM is enabled for.
2. Terminology
L4S: Low Latency, Low Loss, and Scalable Throughput (L4S) as defined
in [RFC9330].
L4S Dual-Queue Coupled AQM: A framework for coupling the Active Queue
Management (AQM) algorithms in two queues intended for flows with
different responses to congestion.
IOAM: In situ Operations, Administration, and Maintenance as defined
in [RFC9197].
OAM: Operations, Administration, and Maintenance.
IOAM Transit Node (IOAM-T): An IOAM transit node updates one or more
of the IOAM-Data-Fields. If both the Pre-allocated and the
Incremental Trace Option-Types are present in the packet, each IOAM
transit node will update at most one of these Option-Types.
IOAM Encapsulating Node (IOAM-E): An IOAM encapsulating node
incorporates one or more IOAM Option-Types into packets that IOAM is
enabled for. If IOAM is enabled for a selected subset of the
traffic, the IOAM encapsulating node is responsible for applying the
IOAM functionality to the selected subset.
IOAM Decapsulating Node (IOAM-DE): An IOAM decapsulating node removes
any IOAM Option-Types from packetsand processes and/or exports the
associated data.
IOAM NODE ID (T-ID): The combination of IOAM node_id and IOAM
Namespace-ID should always be unique.
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Direct Export: Direct Export is an IOAM mode of operation within
which IOAM data are to be directly exported to a collector rather
than be collected within the data packets. The IOAM Direct Export
Option-Type consists of a fixed-size "IOAM direct export option
header". Direct Export for IOAM is defined in [RFC9326].
3. IOAM network awareness in L4S framework
The following are system components for the L4S-IOAM.
+--------------+ +-----------+
+-------------+ | | L4S |
| Monitoring/ | |======>| QUAL-AQM |
| Analytics | | | |
| IOAM-C |-+ +-----------+
+-------------+
^
| Processed/interpreted/
| aggregated IOAM data
|
+--------------+
+-------------+ |
| IOAM data | |
| processing | |
| system(s) |-+
+-------------+
^
| Raw export of
| IOAM data
|
+--------------+-------+------+--------------+
| | | |
| | | |
User +---+----+ +---+----+ +---+----+ +---+-----+
packets | IOAM-E | | IOAM-T | | IOAM-T | | IOAM-DE |
-------->| Node |====>| Node |====>| Node |====>| Node |-->
| | | A | | B | | |
+--------+ +--------+ +--------+ +---------+
Figure 1: L4S-IOAM Schematic
IOAM Control Center (IOAM-C): Store and manage network information
and computing information, and make decisions through a comprehensive
analysis of this information. IOAM-C consists of the IOAM Path
Calculation Unit I-PCE), IOAM Network Metric Information Base(I-NIB),
and IOAM Computing Information Base(I-CIB), and network and computing
information is collected through the IOAM-SBI Interface.
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IOAM Ingress Forwarder (IOAM-E): A network node with a similar SFC
Classifier [RFC7665] forwarding function can classify, encapsulate
(for example, add a packet header with a service path identifier
using the NSH protocol [RFC8300]), and forward incoming traffic.
IOAM-E and IOAM-DE have a L4S Network Metric Agent (L-NMA),
responsible for collecting network information. In L4S-IOAM, L-NMA
reports the collected network information to IOAM-C through the IOAM-
SBI Interface.
The following are system architecture for the L4S-IOAM.
(3) (2) (4)
.-------^------..------------^------------------.
_________
,-(1)-----. _____ | IOAM |
; ________ : L4S -------. | | /_ _ _| Monitor |
:|Scalable| : _ __\ ||__\_|mark | \ | |_________|
:| sender | : __________ / / || / |_____| \ | _________
:|________|\; | |/ -------' ^ \ | |condit'nl|
`---------'\_| IP-ECN | Coupling : \_|_|priority |_\
________ / |Classifier| : / | |scheduler| /
|Classic |/ |__________|\ -------. __:__ / | |_________|
| sender | \_ __\ || | ||__\_|mark/|/ |
|________| / || | || / |drop |/_ _|
Classic -------' |_____|\
(1) Scalable sending host
(2) Isolation in separate network queues
(3) Packet identification protocol
(4) Monitor in network queues
Figure 2: L4S-IOAM architecture
4. Information Details
IOAM for L4S is used to enhance diagnostics of L4S networks. It
complements other mechanisms designed to enhance diagnostics of L4S
networks, such as the "The Explicit Congestion Notification (ECN)
Protocol" described in [RFC9331].
Figure 3 shows awareness information content examples for network
aware which is used to provide L4S services.
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+-------------+----------------------+
| Awareness | Network |
| information | information |
+-------------+----------------------+
| | IOAM-F location; |
| | IOAM-F type; |
| Capability | IOAM-F ID; |
| parameters | Topology information.|
| | |
| | |
| | |
| | |
| | |
+-------------+----------------------+
| | Service request |
| Status | information; |
| parameters | Traffic features; |
| | Communication |
| | information. |
+-------------+----------------------+
Figure 3: L4S-IOAM Information Details
"IOAM tracing data" is expected to be collected at every IOAM transit
node that a packet traverses to ensure visibility into the entire
path that a packet takes within an IOAM-Domain. In other words, in a
typical deployment, all nodes in an IOAM-Domain would participate in
IOAM and, thus, be IOAM transit nodes, IOAM encapsulating nodes, or
IOAM decapsulating nodes. If not all nodes within a domain are IOAM
capable, IOAM tracing information (i.e., node data, see below) will
only be collected on those nodes that are IOAM capable.
IOAM tracing can, for example, collect the following types of
information:
* Identification of the IOAM node. An IOAM node identifier can
match to a device identifier or a particular control point or
subsystem within a device.
* Identification of the interface that a packet was received on,
i.e., ingress interface.
* Identification of the interface that a packet was sent out on,
i.e., egress interface.
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* Time of day when the packet was processed by the node as well as
the transit delay. Different definitions of processing time are
feasible and expected, though it is important that all devices of
an IOAM-Domain follow the same definition.
* Generic data, which is format-free information, where the syntax
and semantics of the information are defined by the operator in a
specific deployment. For a specific IOAM-Namespace, all IOAM
nodes should interpret the generic data the same way. Examples
for generic IOAM data include geolocation information (location of
the node at the time the packet was processed), buffer queue fill
level or cache fill level at the time the packet was processed, or
even a battery charge level.
* Information to detect whether IOAM trace data was added at every
hop or whether certain hops in the domain weren't IOAM transit
nodes.
* Data that relates to how the packet traversed a node (transit
delay, buffer occupancy in case the packet was buffered, and queue
depth in case the packet was queued).
Export of Export of Export of Export of
IOAM data IOAM data IOAM data IOAM data
^ ^ ^ ^
| | | |
| | | |
User +---+----+ +---+----+ +---+----+ +---+-----+
packets | IOAM-E | | IOAM-T | | IOAM-T | | IOAM-DE |
-------->| Node |====>| Node |====>| Node |====>| Node |-->
| | | A | | B | | |
+--------+ +--------+ +--------+ +---------+
Figure 4: L4S-IOAM Direct Export Mode
Consider using Direct Export mode for L4S-IOAM information gathering.
OAM information about each IOAM node a packet traverses is collected
and immediately exported to a collector. Direct Export could be used
in situations where per-hop tracing information is desired, but
gathering the information within the packet -- as with per-hop
tracing -- is not feasible. Rather than automatically correlating
the per-hop tracing information, as done with per-hop tracing, Direct
Export requires a collector to correlate the information from the
individual nodes. In addition, all nodes enabled for Direct Export
need to be capable of exporting the IOAM information to the
collector.
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Those content would allow L4S flows to achieve low latency, low loss
and scalable throughput, but would sacrifice the more precise flow
balance offered by.
5. UseCases
This section gives an example how the application of IOAM technology
in L4S framework can effectively solve the problem that the forward
node in the network is still congested before the L4S node, so the
demand of L4S can also be met in L4S-IOAM, and it is conducive to
reducing the overall delay of the network.
The following use cases for L4S are being considered by various
interested parties:
* where the bottleneck is one of various types of access network,
e.g., DSL, Passive Optical Networks (PONs), DOCSIS cable, mobile,
satellite; or where it's a Wi-Fi link
* private networks of heterogeneous data centres, where there is no
single administrator that can arrange for all the simultaneous
changes to senders, receivers, and networks needed to deploy
DCTCP:
- a set of private data centres interconnected over a wide area
with separate administrations but within the same company
- a set of data centres operated by separate companies
interconnected by a community of interest network (e.g., for
the finance sector)
- multi-tenant (cloud) data centres where tenants choose their
operating system stack (Infrastructure as a Service (IaaS))
* different types of transport (or application) congestion control:
- elastic (TCP/SCTP);
- real-time (RTP, RMCAT); and
- query-response (DNS/LDAP).
* where low delay QoS is required but without inspecting or
intervening above the IP layer :
- Mobile and other networks have tended to inspect higher layers
in order to guess application QoS requirements. However, with
growing demand for support of privacy and encryption, L4S
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offers an alternative. There is no need to select which
traffic to favour for queuing when L4S can give favourable
queuing to all traffic.
* If queuing delay is minimized, applications with a fixed delay
budget can communicate over longer distances or via more
circuitous paths, e.g., longer chains of service functions
[RFC7665] or of onion routers.
* If delay jitter is minimized, it is possible to reduce the
dejitter buffers on the receiving end of video streaming, which
should improve the interactive experience.
6. Contributors
Thanks to Xue Zhang, Ziheng Xu and Xuetong Hu for their contributions
to this document.
7. IANA Considerations
None.
8. Security Considerations
For further study.
9. References
9.1. Normative References
[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
"Network Service Header (NSH)", RFC 8300,
DOI 10.17487/RFC8300, January 2018,
<https://www.rfc-editor.org/info/rfc8300>.
9.2. Informative References
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
[RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
Ed., "Data Fields for In Situ Operations, Administration,
and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197,
May 2022, <https://www.rfc-editor.org/info/rfc9197>.
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[RFC9326] Song, H., Gafni, B., Brockners, F., Bhandari, S., and T.
Mizrahi, "In Situ Operations, Administration, and
Maintenance (IOAM) Direct Exporting", RFC 9326,
DOI 10.17487/RFC9326, November 2022,
<https://www.rfc-editor.org/info/rfc9326>.
[RFC9330] Briscoe, B., Ed., De Schepper, K., Bagnulo, M., and G.
White, "Low Latency, Low Loss, and Scalable Throughput
(L4S) Internet Service: Architecture", RFC 9330,
DOI 10.17487/RFC9330, January 2023,
<https://www.rfc-editor.org/info/rfc9330>.
[RFC9331] De Schepper, K. and B. Briscoe, Ed., "The Explicit
Congestion Notification (ECN) Protocol for Low Latency,
Low Loss, and Scalable Throughput (L4S)", RFC 9331,
DOI 10.17487/RFC9331, January 2023,
<https://www.rfc-editor.org/info/rfc9331>.
[RFC9332] De Schepper, K., Briscoe, B., Ed., and G. White, "Dual-
Queue Coupled Active Queue Management (AQM) for Low
Latency, Low Loss, and Scalable Throughput (L4S)",
RFC 9332, DOI 10.17487/RFC9332, January 2023,
<https://www.rfc-editor.org/info/rfc9332>.
Acknowledgments
The authors wish to thank Xue Zhang, Ziheng Xu and Xuetong Hu, for
their invaluable comments.
Authors' Addresses
Wei Quan
Beijing Jiaotong University
3 Shangyuan Cun, Haidian District
Beijing
P.R. China
Email: weiquan@bjtu.edu.cn
Wei Su
Beijing Jiaotong University
3 Shangyuan Cun, Haidian District
Beijing
P.R. China
Email: wsu@bjtu.edu.cn
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Shuaihao Pan
Beijing Jiaotong University
3 Shangyuan Cun, Haidian District
Beijing
P.R. China
Email: 23111016@bjtu.edu.cn
Xiaobin Liang
China Telecom Research Institute
South District of Future Science and Technology, Changping District
Beijing
P.R. China
Email: liangxb2@chinatelecom.cn
Jie Liang
China Telecom Research Institute
South District of Future Science and Technology, Changping District
Beijing
P.R. China
Email: liangjie6@chinatelecom.cn
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