Operations, Administration and Maintenance (OAM) for Deterministic Networks (DetNet) with MPLS Data Plane
draft-ietf-detnet-mpls-oam-03
DetNet Working Group G. Mirsky
Internet-Draft ZTE Corp.
Intended status: Standards Track M. Chen
Expires: 1 October 2021 Huawei
30 March 2021
Operations, Administration and Maintenance (OAM) for Deterministic
Networks (DetNet) with MPLS Data Plane
draft-ietf-detnet-mpls-oam-03
Abstract
This document defines format and use principals of the Deterministic
Network (DetNet) service Associated Channel (ACH) over a DetNet
network with the MPLS data plane. The DetNet service ACH can be used
to carry test packets of active Operations, Administration, and
Maintenance protocols that are used to detect DetNet failures and
measure performance metrics.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 1 October 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology and Acronyms . . . . . . . . . . . . . . . . 3
2.2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Active OAM for DetNet Networks with MPLS Data Plane . . . . . 4
3.1. DetNet Active OAM Encapsulation . . . . . . . . . . . . . 5
3.2. DetNet Replication, Elimination, and Ordering Sub-functions
Interaction with Active OAM . . . . . . . . . . . . . . . 7
4. Use of Hybrid OAM in DetNet . . . . . . . . . . . . . . . . . 7
5. OAM Interworking Models . . . . . . . . . . . . . . . . . . . 8
5.1. OAM of DetNet MPLS Interworking with OAM of TSN . . . . . 8
5.2. OAM of DetNet MPLS Interworking with OAM of DetNet IP . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9
9.2. Informational References . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
[RFC8655] introduces and explains Deterministic Networks (DetNet)
architecture and how the Packet Replication and Elimination function
(PREF) can be used to ensure low packet drop ratio in DetNet domain.
Operations, Administration and Maintenance (OAM) protocols are used
to detect, localize defects in the network, and monitor network
performance. Some OAM functions, e.g., failure detection, work in
the network proactively, while others, e.g., defect localization,
usually performed on-demand. These tasks achieved by a combination
of active and hybrid, as defined in [RFC7799], OAM methods.
Also, this document defines format and use principals of the DetNet
service Associated Channel over a DetNet network with the MPLS data
plane [I-D.ietf-detnet-mpls].
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2. Conventions used in this document
2.1. Terminology and Acronyms
The term "DetNet OAM" used in this document interchangeably with
longer version "set of OAM protocols, methods and tools for
Deterministic Networks".
CW Control Word
DetNet Deterministic Networks
d-ACH DetNet Associated Channel Header
d-CW DetNet Control Word
DNH DetNet Header
GAL Generic Associated Channel Label
G-ACh Generic Associated Channel
OAM: Operations, Administration and Maintenance
PREF Packet Replication and Elimination Function
POF Packet Ordering Function
PW Pseudowire
RDI Remote Defect Indication
E2E End-to-end
CFM Connectivity Fault Management
BFD Bidirectional Forwarding Detection
TSN Time-Sensitive Network
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 (LSR).
S-Label A DetNet "service" label that is used between DetNet nodes
that implement also the DetNet service sub-layer functions. An
S-Label is also used to identify a DetNet flow at DetNet service sub-
layer.
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Underlay Network or Underlay Layer: The network that provides
connectivity between the DetNet nodes. MPLS network providing LSP
connectivity between DetNet nodes is an example of the underlay
layer.
DetNet Node - a node that is an actor in the DetNet domain. DetNet
domain edge node and node that performs PREF within the domain are
examples of DetNet node.
2.2. Keywords
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. Active OAM for DetNet Networks with MPLS Data Plane
OAM protocols and mechanisms act within the data plane of the
particular networking layer. And thus it is critical that the data
plane encapsulation supports OAM mechanisms in such a way to comply
with the OAM requirements listed in [I-D.tpmb-detnet-oam-framework].
One of such examples that require special consideration is
requirement #5:
DetNet OAM packets MUST be in-band, i.e., follow precisely the
same path as DetNet data plane traffic both for unidirectional and
bi-directional DetNet paths.
The Det Net data plane encapsulation in transport network with MPLS
encapsulation specified in [I-D.ietf-detnet-mpls]. For the MPLS
underlay network, DetNet flows to be encapsulated analogous to
pseudowires (PW) over MPLS packet switched network, as described in
[RFC3985], [RFC4385]. Generic PW MPLS Control Word (CW), defined in
[RFC4385], for DetNet displayed in Figure 1.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DetNet Control Word Format
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PREF in the DetNet domain composed by a combination of nodes that
perform replication and elimination sub-functions. The elimination
sub-function always uses the S-Label and packet sequencing
information, e.g., the value in the Sequence Number field of DetNet
CW (d-CW). The replication sub-function uses the S-Label information
only. For data packets Figure 2 presents an example of PREF in
DetNet domain.
1111 11111111 111111 112212 112212 132213
CE1----EN1--------R1-------R2-------R3--------EN2----CE2
\2 22222/ 3 /
\2222222 /----+ 3 /
+------R4------------------------+
333333333333333333333333
Figure 2: DetNet Data Plane Based on PW
3.1. DetNet Active OAM Encapsulation
DetNet OAM, like PW OAM, uses PW Associated Channel Header defined in
[RFC4385]. Figure 3 displays the encapsulation of a DetNet MPLS
[I-D.ietf-detnet-mpls] active OAM packet.
+---------------------------------+
| |
| DetNet App-Flow |
| Payload Packet |
| |
+---------------------------------+ <--\
| DetNet Associated Channel Header| |
+---------------------------------+ +--> DetNet active OAM
| S-Label | | MPLS encapsulation
+---------------------------------+ |
| [ F-Label(s) ] | |
+---------------------------------+ <--/
| Data-Link |
+---------------------------------+
| Physical |
+---------------------------------+
Figure 3: DetNet Active OAM Packet Encapsulation in MPLS Data Plane
Figure 4 displays encapsulation of a test packet of an active DetNet
OAM protocol in case of MPLS-over-UDP/IP
[I-D.ietf-detnet-mpls-over-udp-ip].
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+---------------------------------+
| |
| DetNet App-Flow |
| Payload Packet |
| |
+---------------------------------+ <--\
| DetNet Associated Channel Header| |
+---------------------------------+ +--> DetNet active OAM
| S-Label | | MPLS encapsulation
+---------------------------------+ |
| [ F-label(s) ] | |
+---------------------------------+ <--+
| UDP Header | |
+---------------------------------+ +--> DetNet data plane
| IP Header | | IP encapsulation
+---------------------------------+ <--/
| Data-Link |
+---------------------------------+
| Physical |
+---------------------------------+
Figure 4: DetNet Active OAM Packet Encapsulation in MPLS-over-UDP/IP
Figure 5 displays the format of the DetNet Associated Channel Header
(d-ACH).
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version|Sequence Number| Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: DetNet Associated Channel Header Format
The meanings of the fields in the d-ACH are:
Bits 0..3 MUST be 0b0001. This value of the first nibble allows
the packet to be distinguished from an IP packet [RFC4928] and a
DetNet data packet [I-D.ietf-detnet-mpls].
Version: this is the version number of the d-ACH. This
specification defines version 0.
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Sequence Number: this is unsigned eight bits-long field. The
originating DetNet node MUST set the value of the Sequence Number
field to a non-zero before packet being transmitted. The
originating node MUST monotonically increase the value of the
Sequence Number field for the every next active OAM packet.
Channel Type: the value of DetNet Associated Channel Type is one
of values defined in the IANA PW Associated Channel Type registry.
The DetNet flow, according to [I-D.ietf-detnet-mpls], is identified
by the S-label that MUST be at the bottom of the stack. Active OAM
packet MUST have d-ACH immediately following the S-label.
3.2. DetNet Replication, Elimination, and Ordering Sub-functions
Interaction with Active OAM
At the DetNet service layer, special functions MAY be applied to the
particular DetNet flow - PREF to potentially lower packet loss,
improve the probability of on-time packet delivery and Packet
Ordering Function (POF) to ensure in-order packet delivery. As data
and the active OAM packets have the same Flow ID, S-label, sub-
functions that rely on sequencing information in the DetNet service
layer MUST process 28 MSBs of the d-ACH as the source of the
sequencing information for the OAM packet.
4. Use of Hybrid OAM in DetNet
Hybrid OAM methods are used in performance monitoring and defined in
[RFC7799] as:
Hybrid Methods are Methods of Measurement that use a combination
of Active Methods and Passive Methods.
A hybrid measurement method may produce metrics as close to passive,
but it still alters something in a data packet even if that is the
value of a designated field in the packet encapsulation. One example
of such a hybrid measurement method is the Alternate Marking method
described in [RFC8321]. Reserving the field for the Alternate
Marking method in the DetNet Header will enhance available to an
operator set of DetNet OAM tools.
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5. OAM Interworking Models
Interworking of two OAM domains that utilize different networking
technology can be realized either by a peering or a tunneling model.
In a peering model, OAM domains are within the corresponding network
domain. When using the peering model, state changes that are
detected by a Fault Management OAM protocol can be mapped from one
OAM domain into another or a notification, e.g., an alarm, can be
sent to a central controller. In the tunneling model of OAM
interworking, usually, only one active OAM protocol is used. Its
test packets are tunneled through another domain along with the data
flow, thus ensuring the fate sharing among test and data packets.
5.1. OAM of DetNet MPLS Interworking with OAM of TSN
Active DetNet OAM is required to provide the E2E fault management and
performance monitoring for a DetNet flow. Interworking of DetNet
active OAM with MPLS data plane with the IEEE 802.1 Time-Sensitive
Networking (TSN) domain based on [I-D.ietf-detnet-mpls-over-tsn].
In the case of the peering model is used in the fault management OAM,
then the node that borders both TSN and DetNet MPLS domains MUST
support [RFC7023]. [RFC7023] specified the mapping of defect states
between Ethernet Attachment Circuits (ACs) and associated Ethernet
PWs that are part of an end-to-end (E2E) emulated Ethernet service.
Requirements and mechanisms described in [RFC7023] are equally
applicable to using the peering model to achieve E2E FM OAM over
DetNet MPLS and TSN domains. The Connectivity Fault Management (CFM)
protocol [IEEE.CFM] or in [ITU.Y1731] can provide fast detection of a
failure in the TSN segment of the DetNet service. In the DetNet MPLS
domain BFD (Bidirectional Forwarding Detection), specified in
[RFC5880] and [RFC5885], can be used. To provide E2E failure
detection, the TSN segment might be presented as a concatenated with
the DetNet MPLS and the Section 6.8.17 [RFC5880] MAY be used to
inform the upstream DetNet MPLS node of a failure of the TSN segment.
Performance monitoring can be supported by [RFC6374] in the DetNet
MPLS and [ITU.Y1731] in the TSN domains, respectively. Performance
objectives for each domain should refer to metrics that additive or
be defined for each domain separately.
The following considerations are to be realized when using the
tunneling model of OAM interworking between DetNet MPLS and TSN
domains:
* Active OAM test packet MUST be mapped to the same TSN Stream ID as
the monitored DetNet flow.
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* Active OAM test packets MUST be treated in the TSN domain based on
its S-label and CoS marking (TC field value).
Note that the tunneling model of the OAM interworking requires that
the remote peer of the E2E OAM domain supports the active OAM
protocol selected on the ingress endpoint. For example, if BFD is
used for proactive path continuity monitoring in the DetNet MPLS
domain, a TSN endpoint of the DetNet service has also support BFD as
defined in [RFC5885].
5.2. OAM of DetNet MPLS Interworking with OAM of DetNet IP
Interworking between active OAM segments in DetNet MPLS and DetNet IP
domains can also be realized using either the peering or the
tunneling model, as discussed in Section 5.1. Using the same
protocol, e.g., BFD, over both segments, simplifies the mapping of
errors in the peering model. To provide the performance monitoring
over a DetNet IP domain STAMP [RFC8762] and its extensions
[I-D.ietf-ippm-stamp-option-tlv] can be used.
6. IANA Considerations
This document does not have any requests for IANA allocation. This
section can be deleted before the publication of the draft.
7. Security Considerations
Additionally, security considerations discussed in DetNet
specifications: [RFC8655], [I-D.ietf-detnet-security],
[I-D.ietf-detnet-mpls] are applicable to this document. Security
concerns and issues related to MPLS OAM tools like LSP Ping
[RFC8029], BFD over PW [RFC5885] also apply to this specification.
8. Acknowledgment
Authors extend their appreciation to Pascal Thubert for his
insightful comments and productive discussion that helped to improve
the document.
9. References
9.1. Normative References
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[I-D.ietf-detnet-mpls]
Varga, B., Farkas, J., Berger, L., Malis, A. G., Bryant,
S., and J. Korhonen, "Deterministic Networking (DetNet)
Data Plane: MPLS", Work in Progress, Internet-Draft,
draft-ietf-detnet-mpls-13, 11 October 2020,
<https://tools.ietf.org/html/draft-ietf-detnet-mpls-13>.
[I-D.ietf-detnet-mpls-over-udp-ip]
Varga, B., Farkas, J., Berger, L., Malis, A. G., and S.
Bryant, "DetNet Data Plane: MPLS over UDP/IP", Work in
Progress, Internet-Draft, draft-ietf-detnet-mpls-over-udp-
ip-08, 14 December 2020, <https://tools.ietf.org/html/
draft-ietf-detnet-mpls-over-udp-ip-08>.
[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>.
[RFC7023] Mohan, D., Ed., Bitar, N., Ed., Sajassi, A., Ed., DeLord,
S., Niger, P., and R. Qiu, "MPLS and Ethernet Operations,
Administration, and Maintenance (OAM) Interworking",
RFC 7023, DOI 10.17487/RFC7023, October 2013,
<https://www.rfc-editor.org/info/rfc7023>.
[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>.
9.2. Informational References
[I-D.ietf-detnet-mpls-over-tsn]
Varga, B., Farkas, J., Malis, A. G., and S. Bryant,
"DetNet Data Plane: MPLS over IEEE 802.1 Time-Sensitive
Networking (TSN)", Work in Progress, Internet-Draft,
draft-ietf-detnet-mpls-over-tsn-07, 19 February 2021,
<https://tools.ietf.org/html/draft-ietf-detnet-mpls-over-
tsn-07>.
[I-D.ietf-detnet-security]
Grossman, E., Mizrahi, T., and A. J. Hacker,
"Deterministic Networking (DetNet) Security
Considerations", Work in Progress, Internet-Draft, draft-
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ietf-detnet-security-16, 2 March 2021,
<https://tools.ietf.org/html/draft-ietf-detnet-security-
16>.
[I-D.ietf-ippm-stamp-option-tlv]
Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A.,
and E. Ruffini, "Simple Two-Way Active Measurement
Protocol Optional Extensions", Work in Progress, Internet-
Draft, draft-ietf-ippm-stamp-option-tlv-10, 15 November
2020, <https://tools.ietf.org/html/draft-ietf-ippm-stamp-
option-tlv-10>.
[I-D.tpmb-detnet-oam-framework]
Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., and C. J.
Bernardos, "Framework of Operations, Administration and
Maintenance (OAM) for Deterministic Networking (DetNet)",
Work in Progress, Internet-Draft, draft-tpmb-detnet-oam-
framework-00, 15 January 2021,
<https://tools.ietf.org/html/draft-tpmb-detnet-oam-
framework-00>.
[IEEE.CFM] IEEE, "Connectivity Fault Management clause of IEEE
802.1Q", IEEE 802.1Q, 2013.
[ITU.Y1731]
ITU-T, "OAM functions and mechanisms for Ethernet based
Networks", ITU-T Recommendation G.8013/Y.1731, November
2013.
[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985,
DOI 10.17487/RFC3985, March 2005,
<https://www.rfc-editor.org/info/rfc3985>.
[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385,
February 2006, <https://www.rfc-editor.org/info/rfc4385>.
[RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal
Cost Multipath Treatment in MPLS Networks", BCP 128,
RFC 4928, DOI 10.17487/RFC4928, June 2007,
<https://www.rfc-editor.org/info/rfc4928>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
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[RFC5885] Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional
Forwarding Detection (BFD) for the Pseudowire Virtual
Circuit Connectivity Verification (VCCV)", RFC 5885,
DOI 10.17487/RFC5885, June 2010,
<https://www.rfc-editor.org/info/rfc5885>.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374,
DOI 10.17487/RFC6374, September 2011,
<https://www.rfc-editor.org/info/rfc6374>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate-Marking Method for Passive and Hybrid
Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
January 2018, <https://www.rfc-editor.org/info/rfc8321>.
[RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
Two-Way Active Measurement Protocol", RFC 8762,
DOI 10.17487/RFC8762, March 2020,
<https://www.rfc-editor.org/info/rfc8762>.
Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com, gregory.mirsky@ztetx.com
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
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