DetNet
Internet Engineering Task Force (IETF) B. Varga, Ed.
Internet-Draft
Request for Comments: 9023 J. Farkas
Intended status:
Category: Informational Ericsson
Expires: August 23, 2021
ISSN: 2070-1721 A. Malis
Malis Consulting
S. Bryant
Futurewei Technologies
February 19,
June 2021
DetNet
Deterministic Networking (DetNet) Data Plane: IP over IEEE 802.1 Time Time-
Sensitive Networking (TSN)
draft-ietf-detnet-ip-over-tsn-07
Abstract
This document specifies the Deterministic Networking IP data plane
when operating over a TSN Time-Sensitive Networking (TSN) sub-network.
This document does not define new procedures or processes. Whenever
this document makes statements or recommendations, these are taken
from normative text in the referenced RFCs.
Status of This Memo
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https://www.rfc-editor.org/info/rfc9023.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Terms Used In in This Document . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
3. DetNet IP Data Plane Overview . . . . . . . . . . . . . . . . 3
4. DetNet IP Flows over an IEEE 802.1 TSN sub-network . . . . 4 Sub-network
4.1. Functions for DetNet Flow to TSN Stream Mapping . . . . . 5
4.2. TSN requirements Requirements of IP DetNet nodes . . . . . . . . . . . 6 Nodes
4.3. Service protection Protection within the TSN sub-network . . . . . . 7 Sub-network
4.4. Aggregation during DetNet flow Flow to TSN Stream mapping . . 7 Mapping
5. Management and Control Implications . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1.
8.1. Normative references . . . . . . . . . . . . . . . . . . 10
9.2. References
8.2. Informative references . . . . . . . . . . . . . . . . . 10 References
Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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
packet-loss rates and assured maximum end-to-end delivery latency.
General background and concepts of DetNet can be found in the DetNet
Architecture [RFC8655].
[RFC8939] specifies the DetNet data plane operation for IP hosts and
routers that provide DetNet service to IP encapsulated IP-encapsulated data. This
document focuses on the scenario where DetNet IP nodes are
interconnected by a TSN Time-Sensitive Networking (TSN) sub-network.
The DetNet Architecture decomposes the DetNet related DetNet-related data plane
functions into two sub-layers: a service sub-layer and a forwarding
sub-layer. The service sub-layer is used to provide DetNet service
protection and reordering. The forwarding sub-layer is used to
provides
provide congestion protection (low loss, assured latency, and limited
reordering). As described in [RFC8939] [RFC8939], no DetNet specific DetNet-specific headers
are added to support DetNet IP flows. So, only the forwarding sub-layer sub-
layer functions can be supported inside the DetNet IP domain.
Service protection can be provided on a per sub-network per-sub-network basis as
shown here for the IEEE802.1 IEEE 802.1 TSN sub-network scenario.
2. Terminology
2.1. Terms Used In in This Document
This document uses the terminology and concepts established in the
DetNet architecture Architecture [RFC8655]. TSN (Time-Sensitive Networking)
specific TSN-specific terms are defined in by the
TSN TG Task Group of the IEEE 802.1 Working Group. The reader is
assumed to be familiar with these documents and their terminology.
2.2. Abbreviations
The following abbreviations are used in this document:
DetNet Deterministic Networking. Networking
FRER Frame Replication and Elimination for Redundancy (TSN
function).
function)
L2 Layer-2. Layer 2
L3 Layer-3. Layer 3
TSN Time-Sensitive Networking, Networking; TSN is a Task Group of the
IEEE 802.1 Working Group.
3. DetNet IP Data Plane Overview
[RFC8939] describes how IP is used by DetNet nodes, i.e., hosts and
routers, to identify DetNet flows and provide a DetNet service. From
a data plane perspective, an end-to-end IP model is followed. DetNet
uses "6-tuple" based flow identification, identification based on a "6-tuple", where "6-tuple" refers
to information carried in IP IP- and higher layer higher-layer protocol headers as
defined in [RFC8939]. .
DetNet flow aggregation may be enabled via the use of wildcards,
masks, prefixes prefixes, and ranges. IP tunnels may also be used to support
flow aggregation. In these cases, it is expected that DetNet aware DetNet-aware
intermediate nodes will provide DetNet service assurance on the
aggregate through resource allocation and congestion control
mechanisms.
Congestion protection, latency control control, and the resource allocation
(queuing, policing, and shaping) are supported using the underlying
link / sub-net specific sub-net-specific mechanisms. Service protections (packet (packet-
replication and packet elimination packet-elimination functions) are not provided at the
IP DetNet layer end-to-end end to end due to the lack of a unified end-to-end
sequencing information that would be available for intermediate
nodes. However, such service protection can be provided on a per
underlying L2 link and sub-network basis. per sub-network.
DetNet routers ensure that DetNet service requirements are met per
hop by allocating local resources, by both receive receiving and transmit,
transmitting, and by mapping the service requirements of each flow to
appropriate sub-
network sub-network mechanisms. Such mappings are sub-network
technology specific. DetNet nodes interconnected by a TSN sub-network sub-
network are the primary focus of this document. The mapping of
DetNet IP flows to TSN streams Streams and TSN protection mechanisms are
covered in Section 4.
4. DetNet IP Flows over an IEEE 802.1 TSN sub-network Sub-network
This section covers how DetNet IP flows operate over an IEEE 802.1
TSN sub-network. Figure 1 illustrates such a scenario, scenario where two IP
(DetNet) nodes are interconnected by a TSN sub-network. Dotted lines
around the Service components of the IP (DetNet) Nodes nodes indicate that
they are DetNet service aware but do not perform any DetNet service
sub-layer function. Node-1 is single homed and Node-2 is dual-homed dual homed
to the TSN sub-network sub-network, and they are treated as Talker or Listener
inside the TSN sub-network. Note, Note that from the TSN perspective dual-
homed perspective,
dual-homed characteristics of Talker or Listener nodes are
transparent to the IP Layer.
IP (DetNet) IP (DetNet)
Node-1 Node-2
............ ............
<--: Service :-- DetNet flow ---: Service :-->
+----------+ +----------+
|Forwarding| |Forwarding|
+--------.-+ <-TSN Str-> +-.-----.--+
\ ,-------. / /
+----[ TSN-Sub ]---+ TSN Sub-]---+ /
[ Network ]--------+
`-------'
<----------------- DetNet IP ----------------->
Figure 1: DetNet (DN) Enabled DetNet-Enabled IP Network over a TSN sub-network Sub-network
At the time of this writing, the Time-Sensitive Networking (TSN) Task
Group of the IEEE 802.1 Working Group have defined (and are defining)
a number of amendments to [IEEE8021Q] that provide zero congestion
loss and bounded latency in bridged networks. Furthermore,
[IEEE8021CB] defines frame replication and elimination functions for
reliability that should prove both compatible with and useful to
DetNet networks. All these functions have to identify flows that
require TSN treatment.
TSN capabilities of the TSN sub-network are made available for IP
(DetNet) flows via the protocol interworking function described in
Annex C.5 of [IEEE8021CB]. For example, applied on the TSN edge port
it can convert an ingress unicast IP (DetNet) flow to use a specific
L2 multicast destination MAC Media Access Control (MAC) address and a VLAN,
VLAN in order to forward the packet through a specific path inside
the bridged network. A similar interworking function pair at the
other end of the TSN sub-
network sub-network would restore the packet to its
original L2 destination MAC address and VLAN.
Placement of TSN functions depends on the TSN capabilities of nodes.
IP (DetNet) Nodes nodes may or may not support TSN functions. For a given
TSN Stream (i.e., a mapped DetNet flow) flow), an IP (DetNet) node is
treated as a Talker or a Listener inside the TSN sub-network.
4.1. Functions for DetNet Flow to TSN Stream Mapping
Mapping of a DetNet IP flow to a TSN Stream is provided via the
combination of a passive and an active stream Stream identification function
that operate at the frame level (Layer-2). (Layer 2). The passive stream Stream
identification function is used to catch the 6-tuple of a DetNet IP
flow
flow, and the active stream Stream identification function is used to modify
the Ethernet header according to the ID of the mapped TSN Stream.
Clause 6.7 of [IEEE8021CB] defines an IP Stream identification
function that can be used as a passive function for IP DetNet flows
using UDP or TCP. Clause 6.8 of [IEEEP8021CBdb] defines a Mask-and-
Match Stream identification function that can be used as a passive
function for any IP DetNet flows.
Clause 6.6 of [IEEE8021CB] defines an Active Destination MAC and VLAN
Stream identification function, what function that can replace some Ethernet header
fields namely
fields: (1) the destination MAC-address, MAC address, (2) the VLAN-ID VLAN-ID, and (3)
priority parameters with alternate values. Replacement is provided
for the frame passed down the stack from the upper layers or up the
stack from the lower layers.
Active Destination MAC and VLAN Stream identification can be used
within a Talker to set flow identity or within a Listener to recover
the original addressing information. It can be used also in a TSN
bridge that is providing translation as a proxy service for an End
System.
4.2. TSN requirements Requirements of IP DetNet nodes Nodes
This section covers the required behavior of a TSN-aware DetNet node
using a TSN sub-network. The implementation of TSN packet processing packet-processing
functions must be compliant with the relevant IEEE 802.1 standards.
From the TSN sub-network perspective perspective, DetNet IP nodes are treated as
a Talker or Listener, Listener that may be (1) TSN-unaware TSN unaware or (2) TSN-aware. TSN aware.
In cases of TSN-unaware IP DetNet nodes nodes, the TSN relay nodes within
the TSN sub-network must modify the Ethernet encapsulation of the
DetNet IP flow (e.g., MAC translation, VLAN-ID setting, Sequence sequence
number addition, etc.) to allow proper TSN specific TSN-specific handling inside
the sub-network. There are no requirements defined for TSN-unaware
IP DetNet nodes in this document.
IP (DetNet) nodes being TSN-aware TSN aware can be treated as a combination of
a TSN-unaware Talker/Listener and a TSN-Relay, TSN relay, as shown in Figure 2.
In such cases cases, the IP (DetNet) node must provide the TSN sub-network sub-network-
specific Ethernet encapsulation over the link(s) towards the sub-
network.
IP (DetNet)
Node
<---------------------------------->
............
<--: Service :-- DetNet flow ------------------
+----------+
|Forwarding|
+----------+ +---------------+
| L2 | | L2 Relay with |<--- TSN ---
| | | TSN function | Stream
+-----.----+ +--.------.---.-+
\__________/ \ \______
\_________
TSN-unaware
Talker / TSN-Bridge TSN Bridge
Listener Relay
<----- TSN Sub-network -----
<------- TSN-aware Tlk/Lstn ------->
Figure 2: IP (DetNet) node Node with TSN functions Functions
A TSN-aware IP (DetNet) node impementations implementation must support the Stream
Identification
identification TSN component for recognizing flows.
A Stream identification component must be able to instantiate the
following functions
following: (1) Active Destination MAC and VLAN Stream
identification function, identification,
(2) IP Stream identification function, identification, (3) Mask-and-Match Stream identification function
identification, and (4) the related managed objects in Clause 9 of
[IEEE8021CB] and [IEEEP8021CBdb].
A TSN-aware IP (DetNet) node implementation must support the
Sequencing function and the Sequence encode/decode function as
defined in Clause Clauses 7.4 and 7.6 of [IEEE8021CB] if FRER is used inside
the TSN sub-network.
The Sequence encode/decode function must support the Redundancy tag
(R-TAG) format as per Clause 7.8 of [IEEE8021CB].
A TSN-aware IP (DetNet) node implementations implementation must support the Stream
splitting function and the Individual recovery function as defined in
Clause
Clauses 7.7 and 7.5 of [IEEE8021CB] when the node is a replication or
elimination point for FRER.
4.3. Service protection Protection within the TSN sub-network Sub-network
TSN Streams supporting DetNet flows may use Frame Replication and
Elimination for Redundancy (FRER) FRER as defined in Clause 8.
8 of [IEEE8021CB] based on the loss service requirements of the TSN
Stream, which is derived from the DetNet service requirements of the
DetNet mapped flow. The specific operation of FRER is not modified
by the use of DetNet and follows [IEEE8021CB].
The FRER function and the provided service recovery is are available
only within the TSN sub-network sub-network, as the TSN Stream-ID Stream ID and the TSN
sequence number are not valid outside the sub-network. An IP
(DetNet) node represents a an L3 border and as such such, it terminates all
related information elements encoded in the L2 frames.
4.4. Aggregation during DetNet flow Flow to TSN Stream mapping Mapping
Implementations of this document shall use management and control
information to map a DetNet flow to a TSN Stream. N:1 mapping
(aggregating DetNet flows in a single TSN Stream) shall be supported.
The management or control function that provisions flow mapping shall
ensure that adequate resources are allocated and configured to
provide proper service requirements of the mapped flows.
5. Management and Control Implications
DetNet flow flows and TSN Stream mapping related Stream-mapping-related information are required
only for TSN-aware IP (DetNet) nodes. From the Data Plane
perspective data plane
perspective, there is no practical difference based on the origin of
flow mapping related
flow-mapping-related information (management plane or control plane).
The following summarizes the set of information that is needed to
configure DetNet IP over TSN:
o DetNet IP related
* DetNet-IP-related configuration information according to the
DetNet role of the DetNet IP node, as per [RFC8939].
o TSN related
* TSN-related configuration information according to the TSN role of
the DetNet IP node, as per [IEEE8021Q], [IEEE8021CB] [IEEE8021CB], and
[IEEEP8021CBdb].
o
* Mapping between DetNet IP flow(s) and TSN Stream(s). DetNet IP
flow identification is summarized in Section 5.1 of [RFC8939], [RFC8939] and
includes all wildcards, port ranges ranges, and the ability to ignore
specific IP fields). For fields. Information on TSN Streams stream Stream identification
information are is defined in [IEEE8021CB] and [IEEEP8021CBdb]).
Note, [IEEEP8021CBdb]. Note
that managed objects for TSN Stream identification can be found in
[IEEEP8021CBcv].
This information must be provisioned per DetNet flow.
Mappings between DetNet and TSN management and control planes are out
of scope of this document. Some of the challenges are highligthed highlighted
below.
TSN-aware IP DetNet nodes are members of both the DetNet domain and
the TSN sub-network. Within the TSN sub-network sub-network, the TSN-aware IP
(DetNet) node has a TSN-aware Talker/Listener role, so TSN specific TSN-specific
management and control plane functionalities must be implemented.
There are many similarities in the management plane techniques used
in DetNet and TSN, but that is not the case for the control plane
protocols. For example, RSVP-TE and MSRP behaves the Multiple Stream Registration
Protocol (MSRP) of IEEE 802.1 behave differently.
Therefore Therefore,
management and control plane design is an important aspect of scenarios,
scenarios where mapping between DetNet and TSN is required.
In order to use a TSN sub-network between DetNet nodes, DetNet DetNet-
specific information must be converted to TSN sub-network specific
ones. sub-network-specific
information. DetNet flow ID and flow related flow-related parameters/requirements
must be converted to a TSN Stream ID and stream related stream-related parameters/
requirements. Note that, as the TSN sub-network is just a portion of
the end-to-end DetNet path (i.e., single hop from an IP perspective),
some parameters (e.g., delay) may differ significantly. Other
parameters (like bandwidth) also may have to be tuned due to the L2
encapsulation used within the TSN sub-network.
In some cases cases, it may be challenging to determine some TSN Stream Stream-
related information. For example, on a TSN-aware IP (DetNet) node
that acts as a Talker, it is quite obvious which DetNet node is the
Listener of the mapped TSN stream Stream (i.e., the IP Next-Hop). However next-hop). However,
it may be not be trivial to locate the point/interface where that
Listener is connected to the TSN sub-network. Such attributes may
require interaction between control and management plane functions
and between DetNet and TSN domains.
Mapping between DetNet flow identifiers and TSN Stream identifiers,
if not provided explicitly, can be done by a TSN-aware IP (DetNet)
node locally based on information provided for configuration of the
TSN Stream identification functions (IP Stream identification, Mask-
and-match
and-Match Stream identification identification, and the active Stream identification
function).
Triggering the setup/modification of a TSN Stream in the TSN sub-
network is an example where management and/or control plane
interactions are required between the DetNet and TSN sub-network.
TSN-unaware IP (DetNet) nodes make such a triggering even more
complicated
complicated, as they are fully unaware of the sub-network and run
independently.
Configuration of TSN specific TSN-specific functions (e.g., FRER) inside the TSN
sub-network is a TSN domain specific TSN-domain-specific decision and may not be visible
in the DetNet domain.
6. Security Considerations
Security considerations for DetNet are described in detail in
[I-D.ietf-detnet-security].
[DETNET-SECURITY]. General security considerations are described in
[RFC8655]. Considerations specific to the DetNet IP data plane specific considerations are
summarized in [RFC8939]. This section considers exclusively discusses security
considerations which that are specific to the DetNet IP over TSN
sub-network IP-over-TSN sub-
network scenario.
The sub-network between DetNet nodes needs to be subject to
appropriate confidentiality. Additionally, knowledge of what DetNet/
TSN services are provided by a sub-network may supply information
that can be used in a variety of security attacks. The ability to
modify information exchanges between connected DetNet nodes may
result in bogus operations. Therefore, it is important that the
interface between DetNet nodes and the TSN sub-network are subject to
authorization, authentication, and encryption.
The TSN sub-network operates at Layer-2 Layer 2, so various security
mechanisms defined by IEEE can be used to secure the connection
between the DetNet nodes (e.g., encryption may be provided using
MACSec
MACsec [IEEE802.1AE-2018]).
7. IANA Considerations
None.
This document has no IANA actions.
8. Acknowledgements
The authors wish to thank Norman Finn, Lou Berger, Craig Gunther,
Christophe Mangin and Jouni Korhonen for their various contributions
to this work.
9. References
9.1.
8.1. Normative references References
[IEEE8021CB]
IEEE, "IEEE Standard for Local and metropolitan area
networks--Frame Replication and Elimination for
Reliability", IEEE 802.1, "Standard 802.1CB-2017,
DOI 10.1109/IEEESTD.2017.8091139, October 2017,
<https://standards.ieee.org/standard/802_1CB-2017.html>.
[IEEEP8021CBdb]
IEEE, "Draft Standard for Local and metropolitan area
networks - -- Frame Replication and Elimination for
Reliability (IEEE Std 802.1CB-2017)", 2017,
<http://standards.ieee.org/about/get/>.
[IEEEP8021CBdb]
Mangin, C., "Extended -- Amendment: Extended Stream identification functions", Identification
Functions", IEEE P802.1CBdb /D1.0 P802.1CBdb, September 2020,
<http://www.ieee802.org/1/files/private/db-drafts/d1/802-
1CBdb-d1-0.pdf>. / D1.3, April 2021,
<https://1.ieee802.org/tsn/802-1cbdb/>.
[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>.
[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>.
9.2.
8.2. Informative references
[I-D.ietf-detnet-security] References
[DETNET-SECURITY]
Grossman, E., Ed., Mizrahi, T., and A. Hacker,
"Deterministic Networking (DetNet) Security
Considerations", draft-ietf-
detnet-security-13 (work Work in progress), December 2020. Progress, Internet-Draft, draft-
ietf-detnet-security-16, March 2021,
<https://tools.ietf.org/html/draft-ietf-detnet-security-
16>.
[IEEE802.1AE-2018]
IEEE Standards Association,
IEEE, "IEEE Std 802.1AE-2018 MAC
Security (MACsec)", Standard for Local and metropolitan area
networks--Media Access Control (MAC) Security", IEEE
802.1AE-2018, DOI 10.1109/IEEESTD.2018.8585421, December
2018, <https://ieeexplore.ieee.org/document/8585421>.
[IEEE8021Q]
IEEE 802.1, "Standard
IEEE, "IEEE Standard for Local and metropolitan area
networks--Bridges Metropolitan Area
Network--Bridges and Bridged Networks (IEEE Networks", IEEE Std 802.1Q-
2018)",
2018, <http://standards.ieee.org/about/get/>. DOI 10.1109/IEEESTD.2018.8403927, July 2018,
<https://ieeexplore.ieee.org/document/8403927>.
[IEEEP8021CBcv]
Kehrer, S., "FRER
IEEE 802.1, "Draft Standard for Local and metropolitan
area networks--Frame Replication and Elimination for
Reliability--Amendment: Information Model, YANG Data Model
and Management Information Base Module", IEEE P802.1CBcv
/D0.4 P802.1CBcv, August 2020,
<https://www.ieee802.org/1/files/private/cv-drafts/d0/802-
1CBcv-d0-4.pdf>.
Draft 1.1, February 2021,
<https://1.ieee802.org/tsn/802-1cbcv/>.
Acknowledgements
The authors wish to thank Norman Finn, Lou Berger, Craig Gunther,
Christophe Mangin, and Jouni Korhonen for their various contributions
to this work.
Authors' Addresses
Balazs
Balázs Varga (editor)
Ericsson
Budapest
Magyar Tudosok krt. 11.
Budapest
1117
Hungary
Email: balazs.a.varga@ericsson.com
Janos
János Farkas
Ericsson
Budapest
Magyar Tudosok krt. 11.
Budapest
1117
Hungary
Email: janos.farkas@ericsson.com
Andrew G. Malis
Malis Consulting
Email: agmalis@gmail.com
Stewart Bryant
Futurewei Technologies
Email: stewart.bryant@gmail.com sb@stewartbryant.com