Internet Engineering Task Force (IETF) B. Varga, Ed.
Request for Comments: 9025 J. Farkas
Category: Standards Track Ericsson
ISSN: 2070-1721 L. Berger
LabN Consulting, L.L.C.
A. Malis
Malis Consulting
S. Bryant
Futurewei Technologies
April 2021
Deterministic Networking (DetNet) Data Plane: MPLS over UDP/IP
Abstract
This document specifies the MPLS Deterministic Networking (DetNet)
data plane operation and encapsulation over an IP network. The
approach is based on the operation of MPLS-over-UDP technology.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9025.
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Table of Contents
1. Introduction
2. Terminology
2.1. Terms Used in This Document
2.2. Abbreviations
2.3. Requirements Language
3. DetNet MPLS Operation over DetNet IP PSNs
4. DetNet Data Plane Procedures
5. Management and Control Information Summary
6. Security Considerations
7. IANA Considerations
8. References
8.1. Normative References
8.2. Informative References
Acknowledgements
Contributors
Authors' Addresses
1. Introduction
Deterministic Networking (DetNet) is a service that can be offered by
a network to DetNet flows. DetNet provides these flows extremely low
packet loss rates and assured maximum end-to-end delivery latency.
General background and concepts of DetNet can be found in [RFC8655].
To carry DetNet MPLS flows with full functionality at the DetNet
layer over an IP network, the following components are required
(these are a subset of the requirements for MPLS encapsulation listed
in [RFC8964]):
1. A method for identifying DetNet flows to the processing element.
2. A method for carrying the DetNet sequence number.
3. A method for distinguishing DetNet Operations, Administration,
and Maintenance (OAM) packets from DetNet data packets.
4. A method for carrying queuing and forwarding indication.
These requirements are satisfied by the DetNet over MPLS
Encapsulation described in [RFC8964] and they are partly satisfied
(i.e., IP flows can be identified; however, no DetNet sequence number
is carried) by the DetNet IP data plane defined in [RFC8939].
This document specifies use of the MPLS DetNet encapsulation over an
IP network. The approach is modeled on the operation of MPLS over an
IP Packet Switched Network (PSN) using UDP encapsulation [RFC7510].
It maps the MPLS data plane encapsulation described in [RFC8964] to
the DetNet IP data plane defined in [RFC8939].
[RFC7510] specifies that "MPLS-in-UDP MUST NOT be used over the
general Internet, or over non-cooperating network operators, to carry
traffic that is not congestion controlled." This constraint does
apply to the use of RFC 7510 in a DetNet network because DetNet is
constrained to operate within a single administrative control or
within a closed group of administrative control.
2. Terminology
2.1. Terms Used in This Document
This document uses the terminology established in the DetNet
architecture [RFC8655]; the reader is assumed to be familiar with
that document and its terminology.
2.2. Abbreviations
The following abbreviations are used in this document:
d-CW A DetNet Control Word (d-CW) is used for sequencing and
identifying duplicate packets of a DetNet flow at the
DetNet service sub-layer.
DetNet Deterministic Networking
DSCP Differentiated Services Code Point
A-Label A special case of an S-Label, whose properties are
known only at the aggregation and deaggregation
endpoints.
F-Label A DetNet "forwarding" label that identifies the LSP
used to forward a DetNet flow across an MPLS PSN, e.g.,
a hop-by-hop label used between label-switching
routers.
MPLS Multiprotocol Label Switching
OAM Operations, Administration, and Maintenance
PEF Packet Elimination Function
POF Packet Ordering Function
PREOF Packet Replication, Elimination, and Ordering Functions
PRF Packet Replication Function
PSN Packet Switched Network
S-Label A DetNet "service" label that is used between DetNet
nodes that also implement the DetNet service sub-layer
functions. An S-Label is also used to identify a
DetNet flow at the DetNet service sub-layer.
2.3. 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. DetNet MPLS Operation over DetNet IP PSNs
This document builds on the specification of MPLS over UDP defined in
[RFC7510]. It may partly or entirely replace the F-Label(s) used in
[RFC8964] with UDP and IP headers. The UDP and IP header information
is used to identify DetNet flows, including member flows, per
[RFC8939]. The resulting encapsulation is shown in Figure 1. There
may be zero or more F-Labels between the S-Label and the UDP header.
Note that this encapsulation works equally well with IPv4, IPv6, and
IPv6-based Segment Routing [RFC8754].
+---------------------------------+
| |
| DetNet App-Flow |
| Payload Packet |
| |
+---------------------------------+ <--\
| DetNet Control Word | |
+---------------------------------+ +--> DetNet data plane
| S-Label | | MPLS encapsulation
+---------------------------------+ |
| [ F-Label(s) ] | |
+---------------------------------+ <--+
| UDP Header | |
+---------------------------------+ +--> DetNet data plane
| IP Header | | IP encapsulation
+---------------------------------+ <--/
| Data-Link |
+---------------------------------+
| Physical |
+---------------------------------+
Figure 1: UDP/IP Encapsulation of DetNet MPLS
S-Labels, A-Labels (when present), d-CW, and zero or more F-Labels
are used as defined in [RFC8964] and are not modified by this
document.
4. DetNet Data Plane Procedures
To support outgoing DetNet MPLS over UDP encapsulation, an
implementation MUST support the provisioning of UDP and IP header
information in addition to or in place of F-Label(s). Note, when the
PRF is performed at the MPLS service sub-layer, there will be
multiple member flows, and each member flow will require the
provisioning of their own UDP and IP header information. The headers
for each outgoing packet MUST be formatted according to the
configuration information and as defined in [RFC7510], and the UDP
Source Port value MUST be set to uniquely identify the DetNet flow.
The packet MUST then be handled as a DetNet IP packet, per [RFC8939].
This includes QoS-related traffic treatment.
To support the receive processing defined in this document, an
implementation MUST also support the provisioning of received UDP and
IP header information. The provisioned information MUST be used to
identify incoming app flows based on the combination of S-Label and
incoming encapsulation header information. Normal receive processing
as defined in [RFC8964], including PEF and POF, can then take place.
5. Management and Control Information Summary
The following summarizes the minimum set of information that is
needed to configure DetNet MPLS over UDP/IP:
* Label information (A-Labels, S-Labels, and F-Labels) to be mapped
to UDP/IP flows. Note that, for example, a single S-Label can map
to multiple sets of UDP/IP information when PREOF is used.
* IPv4 or IPv6 source address field
* IPv4 or IPv6 destination address field
* DSCP Field in either IPv4 Type of Service or IPv6 Traffic Class
Fields
* UDP Source Port
* UDP Destination Port
* Use/non-use of UDP checksum
This information MUST be provisioned per DetNet flow via
configuration, e.g., via the controller [RFC8655] or management
plane. Not using the UDP checksum has to be evaluated on a case-by-
case basis for a given network scenario based on the exception
criteria defined in [RFC7510], particularly when IPv6 is used.
It is the responsibility of the DetNet Controller Plane to properly
provision both flow identification information and the flow-specific
resources needed to provide the traffic treatment needed to meet each
flow's service requirements. This applies for both aggregated and
individual flows.
| Note: In the presence of network (and port) address translation
| devices/functions, it would be up to the Controller Plane to
| determine the appropriate information to ensure proper mapping
| at the sender/receiver.
6. Security Considerations
The solution defined in this document reuses mechanisms specified in
other documents, and the security considerations in those documents
apply equally to this document. Of particular note is [RFC7510], as
this document is primarily an application of MPLS-over-UDP.
Additionally, the security considerations of DetNet in general are
discussed in [RFC8655] and [DETNET-SECURITY]. Finally, MPLS- and IP-
specific security considerations are described in [RFC8964] and
[RFC8939]. This document does not have additional security
considerations.
7. IANA Considerations
This document has no IANA actions.
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>.
[RFC7510] Xu, X., Sheth, N., Yong, L., Callon, R., and D. Black,
"Encapsulating MPLS in UDP", RFC 7510,
DOI 10.17487/RFC7510, April 2015,
<https://www.rfc-editor.org/info/rfc7510>.
[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>.
[RFC8939] Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane:
IP", RFC 8939, DOI 10.17487/RFC8939, November 2020,
<https://www.rfc-editor.org/info/rfc8939>.
[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>.
8.2. Informative References
[DETNET-SECURITY]
Grossman, E., Ed., Mizrahi, T., and A. J. Hacker,
"Deterministic Networking (DetNet) Security
Considerations", Work in Progress, Internet-Draft, draft-
ietf-detnet-security-16, 22 February 2021,
<https://tools.ietf.org/html/draft-ietf-detnet-security-
16>.
[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>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
Acknowledgements
The authors wish to thank Pat Thaler, Norman Finn, Loa Anderson,
David Black, Rodney Cummings, Ethan Grossman, Tal Mizrahi, David
Mozes, Craig Gunther, George Swallow, Yuanlong Jiang, and Carlos
J. Bernardos for their various contributions to this work.
Contributors
This document is derived from an earlier draft that was edited by
Jouni Korhonen (jouni.nospam@gmail.com), and as such, he contributed
to and authored text in this document.
Authors' Addresses
Balázs Varga (editor)
Ericsson
Budapest
Magyar Tudosok krt. 11.
1117
Hungary
Email: balazs.a.varga@ericsson.com
János Farkas
Ericsson
Budapest
Magyar Tudosok krt. 11.
1117
Hungary
Email: janos.farkas@ericsson.com
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
Andrew G. Malis
Malis Consulting
Email: agmalis@gmail.com
Stewart Bryant
Futurewei Technologies
Email: sb@stewartbryant.com
