Internet DRAFT - draft-sx-detnet-mpls-queue
draft-sx-detnet-mpls-queue
DetNet Working Group X. Song
Internet-Draft Q. Xiong
Intended status: Standards Track ZTE Corp.
Expires: 27 September 2023 R. Gandhi
Cisco Systems, Inc.
26 March 2023
MPLS Sub-Stack Encapsulation for Deterministic Latency Action
draft-sx-detnet-mpls-queue-05
Abstract
This document specifies formats and principals for the MPLS header
which contains the Deterministic Latency Action (DLA) option,
designed for use over a DetNet network with MPLS data plane. It
enables guaranteed latency support and makes scheduling decisions for
time-sensitive service running on DetNet nodes that operate within a
constrained network domain.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 27 September 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
3. DetNet DLA Option . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Queuing delay . . . . . . . . . . . . . . . . . . . . . . 4
3.2. DLA Option . . . . . . . . . . . . . . . . . . . . . . . 4
4. MPLS Extension for DLA . . . . . . . . . . . . . . . . . . . 5
4.1. DetNet MPLS Header for DLA . . . . . . . . . . . . . . . 5
4.2. MPLS Sub-Stack for DLA . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
As specified in [RFC8655] and [RFC8938], Deterministic Networking
(DetNet) operates at the IP layer and delivers service with low data
loss rates and bounded latency guarantee within a network domain.
As defined in [RFC8964], the DetNet MPLS data plane provides a
foundation of building blocks to enable PREOF (Packet Replication,
Elimination and Ordering Functions (PREOF)) functions to DetNet
service and forwarding sub-layer. The DetNet service sub-layer
includes a DetNet Control Word (d-CW), service label (S-Label), an
aggregation label (A-Label) in special case of S-Label used for
aggregation. The DetNet forwarding sub-layer supports one or more
forwarding labels (F-Labels) used to forward a DetNet flow over MPLS
domains. The DetNet forwarding sub-layer provides corresponding
forwarding assurance with IETF existing functions using resource
allocations and explicit routes. But these functions may not be
enough to provide the deterministic latency (including bounded
latency, low packet loss and in-order delivery) assurance. Because
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latency variation in one DetNet system results in the need for extra
buffer space in the next-hop DetNet system(s), which in turn
increases the worst-case per-hop latency. So standard queuing and
scheduling algorithms are required to compute and reserve the
sufficient buffer space for DetNet nodes along the path of DetNet
flows.
To support time-sensitive service with ultra-low loss rates and
deterministic latency, it is required to apply feasible scheduling
mechanisms to specific applications for deterministic networking. As
described in [RFC9320], the end-to-end bounded latency is considered
as the sum of non-queuing and queuing delay bounds along with the
queuing mechanisms. The value for non-queuing delay bounds (which
consist of packet output delay, link delay, frame preemption delay
and processing delay) is relative with the physical capability of on-
used networks and can be considered to be stable. The unstable
latency delay bounds are mainly from queuing delay and regulation
delay. The regulation delay is mainly from regulation policy. To
simplify the question this draft assumes there is no regulation
policy. So the question is left to address the selection for queuing
mechanisms and queuing delay information encapsulation in data plane.
The queuing mechanisms, as mentioned in [RFC9320] and [RFC8655],
which include Time Aware Shaping IEEE802.1Qbv, Asynchronous Traffic
Shaping IEEE802.1Qcr, cyclic-scheduling queuing mechanism proposed in
IEEE802.1Qch. There are also discussions on new queuing or
scheduling mechanisms such as [I-D.peng-6man-deadline-option] and
[I-D.dang-queuing-with-multiple-cyclic-buffers]. In terms of delay
guarantee for different applications, to select the right scheduling/
queuing mechanism applied to a specific application is required.
Based on the existing DetNet MPLS encapsulations and mechanisms
[RFC8964], the draft defines the encoding format for Deterministic
Latency Action (DLA) option carried in MPLS sub-stack.
2. Conventions
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.
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2.2. Terminology
Refer to [RFC8655], [RFC8964], [I-D.ietf-mpls-mna-hdr] and [RFC9320]
for the key terms used in this document.
Deterministic Latency (DL):the bound of network latency and delay
variation between two DetNet endpoints. It may includes parameters
such as bounded latency, bounded delay variation, etc.
Deterministic Latency Action (DLA): used to indicate deterministic
latency actions for MPLS Sub-Stack.
3. DetNet DLA Option
3.1. Queuing delay
[RFC8655] provides the architecture for deterministic networking
(DetNet) which enables the service delivery of DetNet flows with
extremely low packet loss rates and deterministic latency. The
forwarding sub-layer provides corresponding forwarding assurance but
can not provide the deterministic latency (including bounded latency,
low packet loss and in-order delivery). As described at [RFC9320],
the end-to-end bounded latency for one DetNet flow is the sum of
delay bound of non-queuing and queuing processing latency. The delay
bound for non-queuing processing may include output delay, link
delay, frame preemption delay, and processing delay, the delay bound
for queuing processing may include regulator delay, queuing delay.
It is assumed that the delay of non-queuing processing is fixed or be
ignorable, the delay of queuing processing is variable. To realize
the guarantee of bounded latency service it is important to select
right queuing methodology applied to specific applications and carry
necessary queuing delay information for computation of end-to-end
latency.
3.2. DLA Option
The DetNet data plane encapsulation in transport network with MPLS
data plane is specified in [RFC8964].
[I-D.xiong-detnet-data-fields-edp] has proposed a commom DetNet data
fields for enhanced DetNet data plane and defined a DLA option to
carry queuing-based metadata.This document provides additional
encapsulation for the DLA in MPLS data plane.
The DetNet routers in data plane perform MPLS forwarding functions to
choose a feasible way with sufficient network resources for the
incoming packets, and makes right selection on the queuing or
scheduling mechanisms applied for specific DetNet flows to satisfy
strict QoS criteria in the forwarding output port. The information
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for the queuing or scheduling mechanisms are carried in DetNet DLA
header. Refer to [I-D.stein-srtsn], considering the time latency
information are processed per hop so the time latency informations
(such as deadline time, cycle identify, etc.) of each DetNet node for
DetNet flows are expected to be carried as a set of lists of LSEs in
MPLS data plane.
4. MPLS Extension for DLA
4.1. DetNet MPLS Header for DLA
The DetNet MPLS header follows [RFC8964], as showed the below figure
1, the SP-Lable (SPL) is added to indicate Deterministic Latency
Action (DLA).
+---------------------------+
| DetNet App-Flow |
| Payload Packet |
+---------------------------+--\
| DetNet Control Word | |
+---------------------------+ |
| S-Label | | DetNet Data Plane
+---------------------------+ | MPLS Encapsulation
| SP-Lable | |
+---------------------------+ |
| F-Label(s) | |
+---------------------------+--/
| Data-Link |
+---------------------------+
| Physical |
+---------------------------+
Figure 1: DetNet MPLS Header
The SP-L (Special Purpose-Label) may be B-SPL [RFC9017], new-SPL,
extended SPL [RFC9017]. This draft follows the MNA (MPLS Network
Action) solution specified in [I-D.ietf-mpls-mna-hdr] and
[I-D.ietf-mpls-mna-fwk], and uses b-SPL to indicate the presence of
the MPLS Network Action Sub-Stack (NASS). The value for the bSPL
value is to be assigned by IANA and follows the assignment in
[I-D.ietf-mpls-mna-hdr]. The SP-Label field is formatted as below
figure.
4.2. MPLS Sub-Stack for DLA
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0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NASI Label = bSPL (TBA1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SP-Label Format
NASI Label:
A new bSPL value is to be assigned by IANA. It is used to indicate
the presence of the MPLS Network Action Sub-Stack (NASS). The
assignment for this field value refers to [I-D.ietf-mpls-mna-hdr].
The MPLS sub-stack encoding format for DLA option is showed as figure
3. The format provides DetNet Latency Network Action Indicator (NAI)
indicates the specific DLA. Its detailed information is carried in
Ancillary Data.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opcode | Flag |S| Data | NAL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| AD LSE1 |S| AD LSE1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| AD LSE2 |S| AD LSE2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... ... ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| AD LSEn |S| AD LSEn |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: MPLS LSE Format for DLA
Opcode (7 bits): This is the first 7-bit value in the Label Field.
The value is used to indicate DLA and to be assigned by IANA.
Flag (16 bits): identifies the type of queuing mechanisms used in the
network. The queuing type format is defined in section 4.2 of
[I-D.xiong-detnet-data-fields-edp].
S (1 bit) : The Bottom of Stack [RFC3032].
Data (4 bits) : Reserved bits for future use.
NAL (4 bits): The DLA action length. It indicates the number of AD
LSEs in the sub-stack.
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The first bit in the Label field of the following AD LSEs MUST be set
to "1". As specified in [I-D.ietf-mpls-mna-hdr] this is to prevent
aliasing the label field with other bSPLs on the legacy routers.
Ancillary Data:
The 19-bit Label field and 4-bit TC field and 8-bit TTL field (except
S bit) in the additional LSEs are used to carry the Ancillary Data
for specific DLA latency information.
The Ancillary Data LSE1 is expected to carry the latency
informationDLA option data defined in section 4.2.2 of
[I-D.xiong-detnet-data-fields-edp] of the edge DetNet node. Depend
on specific queuing mechanisms used in the network the DLA field
length for the latency information for one DetNet node is variable.
The specific queuing (including cycle, deadline, etc.) data
encapsulation are described in [I-D.xiong-detnet-data-fields-edp].
The first AD LSE is expected to carry the latency information for
edge DetNet node. When the length of latency information is more
than 32bits less than 64bits, both AD LSE1 and LSE2 are expected to
carry the latency information for edge DetNet node. In this case,
the DLA option data of next hop is carried in AD LSE3 and LSE4.
Along the path of DetNet flows the AD LSE(n-1) and LSEn carry the DLA
option data for the peer edge DetNet node. With the DetNet flows are
being forwarded in its output ports the corresponding node latency
information carried in DLA options are processed hop by hop.
5. IANA Considerations
This document describes a new IANA-managed registry to identify
DetNet application processing. The registration procedure is "IETF
Review" [RFC8126]. The registry name is "Opcode" and assigned for
DLA Indicator, as defined in Table 1.
+============+=============+===============+
| Value | Description | Reference |
+============+=============+===============+
| Unassigned | Opcode | this document |
+------------+-------------+---------------+
Table 1: DLA Indicator
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6. Security Considerations
Security considerations for DetNet are covered in the DetNet
Architecture RFC8655 and DetNet Security Considerations [RFC9055].
MPLS security considerations are covered in [RFC8964], [RFC3031],
[RFC3032]. These security considerations also apply to this
document.
7. Acknowledgements
The authors would like to acknowledge Shaofu Peng for his thorough
review and very helpful comments.
8. References
8.1. 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>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
[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>.
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[RFC8964] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant,
S., and J. Korhonen, "Deterministic Networking (DetNet)
Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January
2021, <https://www.rfc-editor.org/info/rfc8964>.
[RFC9017] Andersson, L., Kompella, K., and A. Farrel, "Special-
Purpose Label Terminology", RFC 9017,
DOI 10.17487/RFC9017, April 2021,
<https://www.rfc-editor.org/info/rfc9017>.
8.2. Informative References
[I-D.dang-queuing-with-multiple-cyclic-buffers]
Liu, B. and J. Dang, "A Queuing Mechanism with Multiple
Cyclic Buffers", Work in Progress, Internet-Draft, draft-
dang-queuing-with-multiple-cyclic-buffers-00, 22 February
2021, <https://datatracker.ietf.org/doc/html/draft-dang-
queuing-with-multiple-cyclic-buffers-00>.
[I-D.ietf-mpls-mna-fwk]
Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS
Network Actions Framework", Work in Progress, Internet-
Draft, draft-ietf-mpls-mna-fwk-03, 11 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
mna-fwk-03>.
[I-D.ietf-mpls-mna-hdr]
Rajamanickam, J., Gandhi, R., Zigler, R., Song, H., and K.
Kompella, "MPLS Network Action (MNA) Sub-Stack Solution",
Work in Progress, Internet-Draft, draft-ietf-mpls-mna-hdr-
01, 8 March 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-mpls-mna-hdr-01>.
[I-D.peng-6man-deadline-option]
Peng, S., Tan, B., and P. Liu, "Deadline Option", Work in
Progress, Internet-Draft, draft-peng-6man-deadline-option-
01, 11 July 2022, <https://datatracker.ietf.org/doc/html/
draft-peng-6man-deadline-option-01>.
[I-D.stein-srtsn]
Stein, Y. J., "Segment Routed Time Sensitive Networking",
Work in Progress, Internet-Draft, draft-stein-srtsn-01, 29
August 2021, <https://datatracker.ietf.org/doc/html/draft-
stein-srtsn-01>.
[I-D.xiong-detnet-data-fields-edp]
Xiong, Q. and D. Yang, "Data Fields for DetNet Enhanced
Data Plane", Work in Progress, Internet-Draft, draft-
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xiong-detnet-data-fields-edp-00, 10 March 2023,
<https://datatracker.ietf.org/doc/html/draft-xiong-detnet-
data-fields-edp-00>.
[RFC8938] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane
Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,
<https://www.rfc-editor.org/info/rfc8938>.
[RFC9055] Grossman, E., Ed., Mizrahi, T., and A. Hacker,
"Deterministic Networking (DetNet) Security
Considerations", RFC 9055, DOI 10.17487/RFC9055, June
2021, <https://www.rfc-editor.org/info/rfc9055>.
[RFC9320] Finn, N., Le Boudec, J.-Y., Mohammadpour, E., Zhang, J.,
and B. Varga, "Deterministic Networking (DetNet) Bounded
Latency", RFC 9320, DOI 10.17487/RFC9320, November 2022,
<https://www.rfc-editor.org/info/rfc9320>.
Authors' Addresses
Xueyan Song
ZTE Corp.
China
Email: song.xueyan2@zte.com.cn
Quan Xiong
ZTE Corp.
China
Email: xiong.quan@zte.com.cn
Rakesh Gandhi
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
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