DetNet IP Data Plane Encapsulation
draft-ietf-detnet-dp-sol-ip-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Jouni Korhonen , Balazs Varga | ||
| Last updated | 2018-07-05 (Latest revision 2018-07-01) | ||
| Replaces | draft-ietf-detnet-dp-sol | ||
| Replaced by | draft-ietf-detnet-ip, draft-ietf-detnet-data-plane-framework, RFC 8938, RFC 8939 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
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| Consensus boilerplate | Unknown | ||
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| Send notices to | (None) |
draft-ietf-detnet-dp-sol-ip-00
DetNet J. Korhonen, Ed.
Internet-Draft
Intended status: Standards Track B. Varga, Ed.
Expires: January 1, 2019 Ericsson
June 30, 2018
DetNet IP Data Plane Encapsulation
draft-ietf-detnet-dp-sol-ip-00
Abstract
This document specifies Deterministic Networking data plane operation
for IP encapsulated user data.
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 January 1, 2019.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Terms used in this document . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Requirements language . . . . . . . . . . . . . . . . . . 4
3. DetNet IP Data Plane Overview . . . . . . . . . . . . . . . . 4
3.1. DetNet IP Flow Identification . . . . . . . . . . . . . . 7
3.2. DetNet Data Plane Requirements . . . . . . . . . . . . . 8
4. DetNet IP Data Plane Considerations . . . . . . . . . . . . . 8
4.1. End-system specific considerations . . . . . . . . . . . 9
4.2. DetNet domain specific considerations . . . . . . . . . . 10
4.2.1. DetNet Routers . . . . . . . . . . . . . . . . . . . 11
4.3. Networks with multiple technology segments . . . . . . . 12
4.4. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.5. Class of Service . . . . . . . . . . . . . . . . . . . . 12
4.6. Quality of Service . . . . . . . . . . . . . . . . . . . 13
4.7. Cross-DetNet flow resource aggregation . . . . . . . . . 14
4.8. Time synchronization . . . . . . . . . . . . . . . . . . 15
5. Management and control plane considerations . . . . . . . . . 15
5.1. Explicit routes . . . . . . . . . . . . . . . . . . . . . 16
5.2. Service protection . . . . . . . . . . . . . . . . . . . 16
5.3. Congestion protection and latency control . . . . . . . . 16
5.4. Flow aggregation control . . . . . . . . . . . . . . . . 16
5.5. Bidirectional traffic . . . . . . . . . . . . . . . . . . 16
6. DetNet IP Encapsulation Procedures . . . . . . . . . . . . . 17
6.1. Multi-Path Considerations . . . . . . . . . . . . . . . . 17
7. Mapping IP DetNet Flows to IEEE 802.1 TSN . . . . . . . . . . 17
7.1. TSN Stream ID Mapping . . . . . . . . . . . . . . . . . . 18
7.2. TSN Usage of FRER . . . . . . . . . . . . . . . . . . . . 18
7.3. Management and Control Implications . . . . . . . . . . . 18
8. Security considerations . . . . . . . . . . . . . . . . . . . 18
9. IANA considerations . . . . . . . . . . . . . . . . . . . . . 18
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
12.1. Normative references . . . . . . . . . . . . . . . . . . 20
12.2. Informative references . . . . . . . . . . . . . . . . . 22
Appendix A. Example of DetNet data plane operation . . . . . . . 24
Appendix B. Example of pinned paths using IPv6 . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
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.
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General background and concepts of DetNet can be found in the DetNet
Architecture [I-D.ietf-detnet-architecture].
This document specifies the DetNet data plane operation for IP hosts
and routers that provide DetNet service to IP encapsulated data. No
DetNet specific encapsulation is defined to support IP flows, rather
existing IP header information is used to support flow identification
and DetNet service delivery. General background on the use of IP
headers, and "5-tuples", to identify flows and support Quality of
Service (QoS) can be found in [RFC3670]. [RFC7657] also provides
useful background on the delivery differentiated services (DiffServ)
and "6-tuple" based flow identification.
The DetNet Architecture decomposes the DetNet related data plane
functions into two layers: a service layer and a transport layer.
The service layer is used to provide DetNet service protection and
reordering. The transport layer is used to provides congestion
protection (low loss, assured latency, and limited reordering). As
no DetNet specific headers are added to support IP DetNet flows, only
the transport layer functions are supported using the IP DetNet
defined by this document. Service protection can be provided on a
per sub-net basis using technologies such as MPLS
[I-D.ietf-detnet-dp-sol-mpls] and IEEE802.1 TSN.
This document provides an overview of the DetNet IP data plane in
Section 3, considerations that apply to providing DetNet services via
the DetNet IP data plane in Section 4 and Section 5. Section 6
provides the requirements for hosts and routers that support IP-based
DetNet services. Finally, Section 7 provides rules for mapping IP-
based DetNet flows to IEEE 802.1 TSN streams.
2. Terminology
2.1. Terms used in this document
This document uses the terminology and concepts established in the
DetNet architecture [I-D.ietf-detnet-architecture] the reader is
assumed to be familiar with that document.
2.2. Abbreviations
The following abbreviations used in this document:
CE Customer Edge equipment.
CoS Class of Service.
DetNet Deterministic Networking.
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DF DetNet Flow.
L2 Layer-2.
L3 Layer-3.
LSP Label-switched path.
MPLS Multiprotocol Label Switching.
OAM Operations, Administration, and Maintenance.
PE Provider Edge.
PREOF Packet Replication, Ordering and Elimination Function.
PSN Packet Switched Network.
PW Pseudowire.
QoS Quality of Service.
TE Traffic Engineering.
TSN Time-Sensitive Networking, TSN is a Task Group of the
IEEE 802.1 Working Group.
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 IP Data Plane Overview
This document 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.
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IP DetNet Relay Relay IP DetNet
End System Node Node End System
+---------+ +---------+
| Appl. |<--------------- End to End Service ---------->| Appl. |
+---------+ ........... ........... +---------+
| Service |<---: Service :-- DetNet flow ---: Service :-->| Service |
+---------+ +---------+ +---------+ +---------+
|Transport| |Transport| |Transport| |Transport|
+-------.-+ +-.-----.-+ +-.-----.-+ +---.-----+
: Link : \ ,-----. / / ,-----. \
+........+ +-----[ Sub ]----+ +-[ Sub ]-+
[Network] [Network]
`-----' `-----'
|<-DN IP->| |<----- DetNet IP ---->| |<-DN IP->|
Figure 1: A Simple DetNet (DN) Enabled IP Network
Figure 1 illustrates a DetNet enabled IP network. The DetNet enabled
end systems originate IP encapsulated traffic that is identified as
DetNet flows, relay nodes understand the transport requirements of
the DetNet flow and ensure that node, interface and sub-network
resources are allocated to ensure DetNet service requirements. The
dotted line around the Service component of the Relay Nodes indicates
that the transit routers are DetNet service aware but do not perform
any DetNet service layer function, e.g., PREOF. IEEE 802.1 TSN is an
example sub-network type which can provide support for DetNet flows
and service. The mapping of IP DetNet flows to TSN streams and TSN
protection mechanisms is covered in Section 7.
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IP DetNet Relay Transit Relay IP DetNet
End System Node Node Node End System
+---------+ +---------+
| Appl. |<--------------- End to End Service ---------->| Appl. |
+---------+ .....-----+ +-----..... +---------+
| Service |<---: Service |-- DetNet flow ---| Service :-->| Service |
+---------+ +---------+ +---------+ +---------+ +---------+
|Transport| |Trp| |Trp| |Transport| |Trp| |Trp| |Transport|
+-------.-+ +-.-+ +-.-+ +---.---.-+ +-.-+ +-.-+ +---.-----+
: Link : / ,-----. \ : Link : / ,-----. \
+........+ +-[ Sub ]-+ +........+ +-[ Sub ]-+
[Network] [Network]
`-----' `-----'
|<-DN IP->| |<---- DetNet MPLS ---->| |<-DN IP->|
Figure 2: DetNet (DN) IP Over MPLS Network
Figure 2 illustrates a more complex DetNet enabled IP network where
an IP flow is mapped to one or more PWs and MPLS (TE) LSPs. The end
systems still originate IP encapsulated traffic that is identified as
DetNet flows. The relay nodes follow procedures defined in
[I-D.ietf-detnet-dp-sol-mpls] to map each DetNet flow to MPLS LSPs.
While not shown, relay nodes can provide service layer functions such
as PREOF over the MPLS transport layer, and this is indicated by the
solid line for the MPLS facing portion of the Service component.
Note that the Transit node is MPLS (TE) LSP aware and performs
switching based on MPLS labels, and need not have any specific
knowledge of the DetNet service or the corresponding DetNet flow
identification. See [I-D.ietf-detnet-dp-sol-mpls] for details on the
mapping of IP flows to MPLS as well as general support for DetNet
services using MPLS.
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IP Edge Edge IP
End System Node Node End System
+---------+ +.........+ +.........+ +---------+
| Appl. |<---:Svc Proxy:-- E2E Service ---:Svc Proxy:-->| Appl. |
+---------+ +---------+ +---------+ +---------+
| IP | |IP | |Svc|<-- DetNet flow ->|Svc| |IP | | IP |
+---------+ +---+ +---+ +---+ +---+ +---------+
|Transport| |Trp| |Trp| |Trp| |Trp| |Transport|
+-------.-+ +-.-+ +-.-+ +-.-+ +-.-+ +---.-----+
: Link : \ ,-----. / / ,-----. \
+........+ +-----[ Sub ]---+ +-[ Sub ]-+
[Network] [Network]
`-----' `-----'
|<----IP --->| |<----- DetNet IP ------>| |<----IP --->|
Figure 3: Non-DetNet aware IP end systems with IP DetNet Domain
Figure 3 illustrates a variant of Figure 1 where the end systems are
not DetNet aware. In this case, edge nodes sit at the boundary of
the DetNet domain and act as DetNet service proxies for the end
applications by initiating and terminating DetNet service for the
non-DetNet aware IP flows. The existing header information or an
approach such as described in Section 4.7 can be used to support
DetNet flow identification.
3.1. DetNet IP Flow Identification
DetNet IP flows are identified based on IP, both IPv4 [RFC0791] and
IPv6 [RFC8200], header information. 6 header fields are used and
this set of fields is commonly referred to as the IP header
"6-tuple". The 6 fields include the IP source and destination
address fields, the next level protocol or header field, the next
level protocol (e.g. TCP or UDP) source and destination ports, and
the IPv4 Type of Service or IPv6 Traffic Class field (i.e., DSCP).
As part of single DetNet flow identification, any of the fields can
be ignored (wildcarded), and bit masks, prefix based longest match,
and ranges can also be used.
DetNet flow aggregation may be enabled via the use of wildcards,
masks, prefixes and ranges. IP tunnels may also be used to support
flow aggregation. In these cases, it is expected that DetNet aware
intermediate nodes will provide DetNet service assurance on the
aggregate through resource allocation and congestion control
mechanisms.
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3.2. DetNet Data Plane Requirements
Two major groups of scenarios can be distinguished which require flow
identification during transport:
1. DetNet function related scenarios:
Congestion protection and latency control:
Usage of allocated resources (queuing, policing, shaping) to
ensure that the congestion-related loss and latency/jitter
requirements of a DetNet flow are met.
Explicit routes: a reservation that maps a flow to a specific
path, which also limits miss-ordering and jitter. The
spreading of a single DetNet flow across multiple paths, e.g.,
via ECMP, also impacts ordering and end-to-end jitter, and as
such use of multiple paths for support of a single DetNet flow
is is out of scope this document.
Service protection:
Which in the case of this document translates to changing the
explicit path after a failure is detected while maintaining
the required DetNet service characteristics. Path changes,
even in the case of failure recovery, can lead to the out of
order delivery of data. Note: DetNet PREOF is not provided by
the mechanisms defined in this document.
2. OAM function related scenarios:
Troubleshooting:
For example, identify misbehaving flows.
Recognize flow(s) for analytics:
For example, increase counters.
Correlate events with flows:
For example, volume above threshold.
4. DetNet IP Data Plane Considerations
This section provides informative considerations related to providing
DetNet services via IP.
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4.1. End-system specific considerations
Data-flows requiring DetNet service are generated and terminated on
end systems. The specific protocols used by an end system are
specific to an application. This said, DetNet's use of 6-tuple IP
flow identification means that DetNet must be aware of not only the
format of the IP header, but also of the next protocol carried within
an IP packet.
When IP end systems are DetNet aware, no application-level or
service-level proxy functions are needed inside the DetNet domain, so
end systems peer with end systems using the same application
encapsulation format (see Figure 4).
+-----+
| X | +-----+
+-----+ | X |
| IP | ________ +-----+
+-----+ _____ / \ | IP |
\ / \__/ \___ +-----+
\ / \ /
0========= flow-1 =========0_
| \
\ |
0========== flow-2 ==========0
/ \ __/ \
+-----+ \__ DetNet domain / \
| X | \ __ / +-----+
+-----+ \_______/ \_____/ | X |
| IP | +-----+
+-----+ | IP |
+-----+
Figure 4: End-systems and the DetNet domain
End systems need to ensure that DetNet service requirements are met
when processing packets associated with a DetNet flow. When
transporting packets, this generally means that packets are
appropriately shaped on transmission and received appropriate traffic
treatment on the connected sub-network, see Section 4.6 and
Section 4.2.1 for more details. When receiving packets, this
generally means that there are appropriate local node resources,
e.g., buffers, to receive and process a DetNet flow packets.
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4.2. DetNet domain specific considerations
As a general rule, DetNet domains need to be able to forward any
DetNet flow identified by the IP 6-tuple. Doing otherwise would
limit end system encapsulation format. From a practical standpoint
this means that all nodes along the end-to-end path of a DetNet flows
need to agree on what fields are used for flow identification, and
the transport protocols (e.g., TCP/UDP/IPsec) which can be used to
identify 6-tuple protocol ports.
[Editor's note: Update accordingly. BV to take a pass at update.]
From a connection type perspective three scenarios are identified:
1. Directly attached: end system is directly connected to an edge
node.
2. Indirectly attached: end system is behind a (L2-TSN / L3-DetNet)
sub-networks.
3. DN integrated: end system is part of the DetNet domain.
L3 end systems may use any of these connection types, however L2 end
systems may use only the first two (directly or indirectly attached).
DetNet domain MUST allow communication between any end-systems of the
same type (L2-L2, L3-L3), independent of their connection type and
DetNet capability. However, directly attached and indirectly
attached end systems have no knowledge about the DetNet domain and
its encapsulation format at all. See Figure 5 for L3 end system
connection scenarios.
____+----+
+----+ _____ / | ES3|
| ES1|____ / \__/ +----+___
+----+ \ / \
+ |
____ \ _/
+----+ __/ \ +__ DetNet domain /
| ES2|____/ L2/L3 |___/ \ __ __/
+----+ \_______/ \_______/ \___/
Figure 5: Connection types of L3 end systems
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4.2.1. DetNet Routers
Within a DetNet domain, the DetNet enabled IP Routers interconnect
links and sub-networks to support end-to-end delivery of DetNet
flows. From a DetNet architecture perspective, these routers are
DetNet relays, as they must be DetNet service aware. Such routers
identify DetNet flows based on the IP 6-tuple, and ensure that the
DetNet service required traffic treatment is provided both on the
node and on any attached sub-network.
This solution provides DetNet functions end to end, but does so on a
per link and sub-network basis. Congestion protection and latency
control and the resource allocation (queuing, policing, shaping) are
supported using the underlying link / sub net specific mechanisms.
However, service protections (packet replication and packet
emilination functions) are not provided at the DetNet layer end to
end. But such service protection can be provided on a per underlying
L2 link and sub-network basis.
+------+ +------+
| X | | X |
+======+ +------+
End-system | IP | | IP |
-----+------+-------+======+--- --+======+--
DetNet |L2/SbN| |L2/SbN|
+------+ +------+
Figure 6: Encapsulation of DetNet Routing in simplified IP service L3
end-systems
Note: the DetNet Service Flow MUST be mapped to the link / sub-
network specific resources using an underlying system specific means.
This implies each DetNet aware node on path MUST look into the
transported DetNet Service Flow packet and utilize e.g., a 5- (or 6-)
tuple to find out the required mapping within a node. As noted
earlier, the Service Protection is done within each link / sub-
network independently using the domain specific mechanisms (due the
lack of a unified end to end sequencing information that would be
available for intermediate nodes). If end to end service protection
is desired that can be implemented, for example, by the DetNet end
systems using Layer-4 (L4) transport protocols or application
protocols. However, these are out of scope of this document.
[Editor's note: the service protection to be clarified further.]
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4.3. Networks with multiple technology segments
There are network scenarios, where the DetNet domain contains
multiple technology segments (IEEE 802.1 TSN, MPLS) and all those
segments are under the same administrative control (see Figure 7).
Furthermore, DetNet nodes may be interconnected via TSN segments.
DetNet routers ensure that detnet service requirements are met per
hop by allocating local resources, both receive and transmit, and by
mapping the service requirements of each flow to appropriate sub-
network mechanisms. Such mapping is sub-network technology specific.
The mapping of IP DetNet Flows to MPLS is covered
[I-D.ietf-detnet-dp-sol-mpls]. The mapping of IP DetNet Flows to
IEEE 802.1 TSN is covered in Section 7.
______
_____ / \__
____ / \__/ \___ ______
+----+ __/ +======+ +==+ \ +----+
|src |__/ Seg1 ) | | \ Seg3 \__| dst|
+----+ \_______+ \ Segment-2 | \+_____/ +----+
\======+__ _+===/
\ __ __/
\_______/ \___/
Figure 7: DetNet domains and multiple technology segments
4.4. OAM
[Editor's note: This section is TBD]
4.5. Class of Service
[Editor's note: this section is TBD]
Class and quality of service, i.e., CoS and QoS, are terms that are
often used interchangeably and confused. In the context of DetNet,
CoS is used to refer to mechanisms that provide traffic forwarding
treatment based on aggregate group basis and QoS is used to refer to
mechanisms that provide traffic forwarding treatment based on a
specific DetNet flow basis. Examples of existing network level CoS
mechanisms include DiffServ which is enabled by IP header
differentiated services code point (DSCP) field [RFC2474] and MPLS
label traffic class field [RFC5462], and at Layer-2, by IEEE 802.1p
priority code point (PCP).
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CoS for DetNet flows carried in PWs and MPLS is provided using the
existing MPLS Differentiated Services (DiffServ) architecture
[RFC3270]. Both E-LSP and L-LSP MPLS DiffServ modes MAY be used to
support DetNet flows. The Traffic Class field (formerly the EXP
field) of an MPLS label follows the definition of [RFC5462] and
[RFC3270]. The Uniform, Pipe, and Short Pipe DiffServ tunneling and
TTL processing models are described in [RFC3270] and [RFC3443] and
MAY be used for MPLS LSPs supporting DetNet flows. MPLS ECN MAY also
be used as defined in ECN [RFC5129] and updated by [RFC5462].
CoS for DetNet flows carried in IPv6 is provided using the standard
differentiated services code point (DSCP) field [RFC2474] and related
mechanisms. The 2-bit explicit congestion notification (ECN)
[RFC3168] field MAY also be used.
One additional consideration for DetNet nodes which support CoS
services is that they MUST ensure that the CoS service classes do not
impact the congestion protection and latency control mechanisms used
to provide DetNet QoS. This requirement is similar to requirement
for MPLS LSRs to that CoS LSPs do not impact the resources allocated
to TE LSPs via [RFC3473].
4.6. Quality of Service
[Editor's note: Keep this section. We should document the used
technologies but the detailed discussion may go somewhere else. We
should start having it here and then decide whether to move to some
other document.]
Quality of Service (QoS) mechanisms for flow specific traffic
treatment typically includes a guarantee/agreement for the service,
and allocation of resources to support the service. Example QoS
mechanisms include discrete resource allocation, admission control,
flow identification and isolation, and sometimes path control,
traffic protection, shaping, policing and remarking. Example
protocols that support QoS control include Resource ReSerVation
Protocol (RSVP) [RFC2205] (RSVP) and RSVP-TE [RFC3209] and [RFC3473].
The existing MPLS mechanisms defined to support CoS [RFC3270] can
also be used to reserve resources for specific traffic classes.
In addition to explicit routes, and packet replication and
elimination, DetNet provides zero congestion loss and bounded latency
and jitter. As described in [I-D.ietf-detnet-architecture], there
are different mechanisms that maybe used separately or in combination
to deliver a zero congestion loss service. These mechanisms are
provided by the either the MPLS or IP layers, and may be combined
with the mechanisms defined by the underlying network layer such as
802.1TSN.
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A baseline set of QoS capabilities for DetNet flows carried in PWs
and MPLS can provided by MPLS with Traffic Engineering (MPLS-TE)
[RFC3209] and [RFC3473]. TE LSPs can also support explicit routes
(path pinning). Current service definitions for packet TE LSPs can
be found in "Specification of the Controlled Load Quality of
Service", [RFC2211], "Specification of Guaranteed Quality of
Service", [RFC2212], and "Ethernet Traffic Parameters", [RFC6003].
Additional service definitions are expected in future documents to
support the full range of DetNet services. In all cases, the
existing label-based marking mechanisms defined for TE-LSPs and even
E-LSPs are use to support the identification of flows requiring
DetNet QoS.
QoS for DetNet service flows carried in IP MUST be provided locally
by the DetNet-aware hosts and routers supporting DetNet flows. Such
support will leverage the underlying network layer such as 802.1TSN.
The traffic control mechanisms used to deliver QoS for IP
encapsulated DetNet flows are expected to be defined in a future
document. From an encapsulation perspective, the combination of the
"6 tuple" i.e., the typical 5 tuple enhanced with the DSCP code,
uniquely identifies a DetNet service flow.
Packets that are marked with a DetNet Class of Service value, but
that have not been the subject of a completed reservation, can
disrupt the QoS offered to properly reserved DetNet flows by using
resources allocated to the reserved flows. Therefore, the network
nodes of a DetNet network must:
o Defend the DetNet QoS by discarding or remarking (to a non-DetNet
CoS) packets received that are not the subject of a completed
reservation.
o Not use a DetNet reserved resource, e.g. a queue or shaper
reserved for DetNet flows, for any packet that does not carry a
DetNet Class of Service marker.
4.7. Cross-DetNet flow resource aggregation
[Editor's note: Aggregation is FFS. The addregation can be provided
via encapsulation or header wildcards]
The ability to aggregate individual flows, and their associated
resource control, into a larger aggregate is an important technique
for improving scaling of control in the data, management and control
planes. This document identifies the traffic identification related
aspects of aggregation of DetNet flows. The resource control and
management aspects of aggregation (including the queuing/shaping/
policing implications) will be covered in other documents. The data
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plane implications of aggregation are independent for PW/MPLS and IP
encapsulated DetNet flows.
DetNet flows transported via IP have more limited aggregation
options, due to the available traffic flow identification fields of
the IP solution. One available approach is to manage the resources
associated with a DSCP identified traffic class and to map (remark)
individually controlled DetNet flows onto that traffic class. This
approach also requires that nodes support aggregation ensure that
traffic from aggregated LSPs are placed (shaped/policed/enqueued) in
a fashion that ensures the required DetNet service is preserved.
In both the MPLS and IP cases, additional details of the traffic
control capabilities needed at a DetNet-aware node may be covered in
the new service descriptions mentioned above or in separate future
documents. Management and control plane mechanisms will also need to
ensure that the service required on the aggregate flow (H-LSP or
DSCP) are provided, which may include the discarding or remarking
mentioned in the previous sections.
4.8. Time synchronization
While time synchronization can be important both from the perspective
of operating the DetNet network itself and from the perspective of
DetNet-based applications, time synchronization is outside the scope
of this document. This said, a DetNet node can also support time
synchronization or distribution mechanisms.
For example, [RFC8169] describes a method of recording the packet
queuing time in an MPLS LSR on a packet by per packet basis and
forwarding this information to the egress edge system. This allows
compensation for any variable packet queuing delay to be applied at
the packet receiver. Other mechanisms for IP networks are defined
based on IEEE Standard 1588 [IEEE1588], such as ITU-T [G.8275.1] and
[G.8275.2].
A more detailed discussion of time synchronization is outside the
scope of this document.
5. Management and control plane considerations
[Editor's note: This section needs to be different for MPLS and IP
solutions. Most solutions are technology dependant.]
While management plane and control plane are traditionally considered
separately, from the Data Plane perspective there is no practical
difference based on the origin of flow provisioning information.
This document therefore does not distinguish between information
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provided by a control plane protocol, e.g., RSVP-TE [RFC3209] and
[RFC3473], or by a network management mechanisms, e.g., RestConf
[RFC8040] and YANG [RFC7950].
[Editor's note: This section is a work in progress. discuss here
what kind of enhancements are needed for DetNet and specifically for
PREOF and DetNet zero congest loss and latency control. Need to
cover both traffic control (queuing) and connection control (control
plane).]
5.1. Explicit routes
[Editor's note: this is TBD.]
5.2. Service protection
[Editor's note: this is TBD.]
5.3. Congestion protection and latency control
[Editor's note: this is TBD.]
5.4. Flow aggregation control
[Editor's note: this is TBD.]
5.5. Bidirectional traffic
[Editor's note: This is managed at the management plane or controller
level.]
Some DetNet applications generate bidirectional traffic. While the
DetNet data plane must support bidirectional DetNet flows, there are
no special bidirectional features with respect to the data plane
other than need for the two directions take the same paths. That is
to say that bidirectional DetNet flows are solely represented at the
management and control plane levels, without specific support or
knowledge within the DetNet data plane. Fate sharing and associated
vs co-routed bidirectional flows can be managed at the control level.
Note, that there is no stated requirement for bidirectional DetNet
flows to be supported using the same 6-tuple in each direction.
Control mechanisms will need to support such bidirectional flows but
such mechanisms are out of scope of this document. An example
control plane solution for MPLS can be found in [RFC7551].
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6. DetNet IP Encapsulation Procedures
[Editor's note: RFC2119 conformance language goes here Need to
support flow identification Based on 4 IP header fields {ip addrs,
dscp, nct protocol} need to support port identification for TCP/UDP,
IPsec spi (?), what else? Service proxies -- basically same from
data plane, different from management map to local resources]
6.1. Multi-Path Considerations
[Note: talk about implications of ECMP/LAG/parallel links -- perhaps
just say support for such is not covered in the document.]
7. Mapping IP DetNet Flows to IEEE 802.1 TSN
[Editor's note: This section is TBD - it covers how IP DetNet flows
operate over an IEEE 802.1 TSN sub-network. BV to take a pass at
filling in this section]
The Time-Sensitive Networking (TSN) Task Group of the IEEE 802.1
Working Group have defined (and are defining) a number of amendments
to IEEE 802.1Q [IEEE8021Q] that provide zero congestion loss and
bounded latency in bridged networks. IEEE 802.1CB [IEEE8021CB]
defines packet replication and elimination functions that should
prove both compatible with and useful to, DetNet networks.
As is the case for DetNet, a Layer 2 network node such as a bridge
may need to identify the specific DetNet flow to which a packet
belongs in order to provide the TSN/DetNet QoS for that packet. It
also will likely need a CoS marking, such as the priority field of an
IEEE Std 802.1Q VLAN tag, to give the packet proper service.
Although the flow identification methods described in IEEE 802.1CB
[IEEE8021CB] are flexible, and in fact, include IP 5-tuple
identification methods, the baseline TSN standards assume that every
Ethernet frame belonging to a TSN stream (i.e. DetNet flow) carries
a multicast destination MAC address that is unique to that flow
within the bridged network over which it is carried. Furthermore,
IEEE 802.1CB [IEEE8021CB] describes three methods by which a packet
sequence number can be encoded in an Ethernet frame.
Ensuring that the proper Ethernet VLAN tag priority and destination
MAC address are used on a DetNet/TSN packet may require further
clarification of the customary L2/L3 transformations carried out by
routers and edge label switches. Edge nodes may also have to move
sequence number fields among Layer 2, PW, and IPv6 encapsulations.
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7.1. TSN Stream ID Mapping
[Editor's Note: This section covers the data plane aspects of mapping
an IP DetNet flow to one or more TSN Stream-IDs.]
7.2. TSN Usage of FRER
[Core point] TSN Streams support DetNet flows may use Frame
Replication and Elimination for Redundancy (FRER) [802.1CB] 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 the FRER is not modified by the use of DetNe
and follows IEEE 802.1CB [IEEE8021CB].
7.3. Management and Control Implications
[Editor's note: This section is TBD Covers Creation, mapping, removal
of TSN Stream IDs, related parameters and,when needed, configuration
of FRER. Supported by management/control plane.]
8. Security considerations
The security considerations of DetNet in general are discussed in
[I-D.ietf-detnet-architecture] and [I-D.ietf-detnet-security]. Other
security considerations will be added in a future version of this
draft.
9. IANA considerations
TBD.
10. Contributors
RFC7322 limits the number of authors listed on the front page of a
draft to a maximum of 5, far fewer than the 20 individuals below who
made important contributions to this draft. The editor wishes to
thank and acknowledge each of the following authors for contributing
text to this draft. See also Section 11.
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Loa Andersson
Huawei
Email: loa@pi.nu
Yuanlong Jiang
Huawei
Email: jiangyuanlong@huawei.com
Norman Finn
Huawei
3101 Rio Way
Spring Valley, CA 91977
USA
Email: norman.finn@mail01.huawei.com
Janos Farkas
Ericsson
Magyar Tudosok krt. 11
Budapest 1117
Hungary
Email: janos.farkas@ericsson.com
Carlos J. Bernardos
Universidad Carlos III de Madrid
Av. Universidad, 30
Leganes, Madrid 28911
Spain
Email: cjbc@it.uc3m.es
Tal Mizrahi
Marvell
6 Hamada st.
Yokneam
Israel
Email: talmi@marvell.com
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
11. Acknowledgements
The author(s) ACK and NACK.
The following people were part of the DetNet Data Plane Solution
Design Team:
Jouni Korhonen
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Janos Farkas
Norman Finn
Balazs Varga
Loa Andersson
Tal Mizrahi
David Mozes
Yuanlong Jiang
Carlos J. Bernardos
The DetNet chairs serving during the DetNet Data Plane Solution
Design Team:
Lou Berger
Pat Thaler
Thanks for Stewart Bryant for his extensive review of the previous
versions of the document.
12. References
12.1. Normative references
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[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>.
[RFC2211] Wroclawski, J., "Specification of the Controlled-Load
Network Element Service", RFC 2211, DOI 10.17487/RFC2211,
September 1997, <https://www.rfc-editor.org/info/rfc2211>.
[RFC2212] Shenker, S., Partridge, C., and R. Guerin, "Specification
of Guaranteed Quality of Service", RFC 2212,
DOI 10.17487/RFC2212, September 1997,
<https://www.rfc-editor.org/info/rfc2212>.
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[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, DOI 10.17487/RFC3168, September 2001,
<https://www.rfc-editor.org/info/rfc3168>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen,
P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
Protocol Label Switching (MPLS) Support of Differentiated
Services", RFC 3270, DOI 10.17487/RFC3270, May 2002,
<https://www.rfc-editor.org/info/rfc3270>.
[RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing
in Multi-Protocol Label Switching (MPLS) Networks",
RFC 3443, DOI 10.17487/RFC3443, January 2003,
<https://www.rfc-editor.org/info/rfc3443>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003,
<https://www.rfc-editor.org/info/rfc3473>.
[RFC5129] Davie, B., Briscoe, B., and J. Tay, "Explicit Congestion
Marking in MPLS", RFC 5129, DOI 10.17487/RFC5129, January
2008, <https://www.rfc-editor.org/info/rfc5129>.
[RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching
(MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
Class" Field", RFC 5462, DOI 10.17487/RFC5462, February
2009, <https://www.rfc-editor.org/info/rfc5462>.
[RFC6003] Papadimitriou, D., "Ethernet Traffic Parameters",
RFC 6003, DOI 10.17487/RFC6003, October 2010,
<https://www.rfc-editor.org/info/rfc6003>.
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[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>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
12.2. Informative references
[G.8275.1]
International Telecommunication Union, "Precision time
protocol telecom profile for phase/time synchronization
with full timing support from the network", ITU-T
G.8275.1/Y.1369.1 G.8275.1, June 2016,
<https://www.itu.int/rec/T-REC-G.8275.1/en>.
[G.8275.2]
International Telecommunication Union, "Precision time
protocol telecom profile for phase/time synchronization
with partial timing support from the network", ITU-T
G.8275.2/Y.1369.2 G.8275.2, June 2016,
<https://www.itu.int/rec/T-REC-G.8275.2/en>.
[I-D.ietf-detnet-architecture]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-05 (work in progress), May 2018.
[I-D.ietf-detnet-dp-sol-mpls]
Korhonen, J., Varga, B., "DetNet MPLS Data Plane
Encapsulation", 2018.
[I-D.ietf-detnet-security]
Mizrahi, T., Grossman, E., Hacker, A., Das, S., Dowdell,
J., Austad, H., Stanton, K., and N. Finn, "Deterministic
Networking (DetNet) Security Considerations", draft-ietf-
detnet-security-02 (work in progress), April 2018.
[IEEE1588]
IEEE, "IEEE 1588 Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems Version 2", 2008.
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[IEEE8021CB]
Finn, N., "Draft Standard for Local and metropolitan area
networks - Seamless Redundancy", IEEE P802.1CB
/D2.1 P802.1CB, December 2015,
<http://www.ieee802.org/1/files/private/cb-drafts/
d2/802-1CB-d2-1.pdf>.
[IEEE8021Q]
IEEE 802.1, "Standard for Local and metropolitan area
networks--Bridges and Bridged Networks (IEEE Std 802.1Q-
2014)", 2014, <http://standards.ieee.org/about/get/>.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <https://www.rfc-editor.org/info/rfc2205>.
[RFC3670] Moore, B., Durham, D., Strassner, J., Westerinen, A., and
W. Weiss, "Information Model for Describing Network Device
QoS Datapath Mechanisms", RFC 3670, DOI 10.17487/RFC3670,
January 2004, <https://www.rfc-editor.org/info/rfc3670>.
[RFC7551] Zhang, F., Ed., Jing, R., and R. Gandhi, Ed., "RSVP-TE
Extensions for Associated Bidirectional Label Switched
Paths (LSPs)", RFC 7551, DOI 10.17487/RFC7551, May 2015,
<https://www.rfc-editor.org/info/rfc7551>.
[RFC7657] Black, D., Ed. and P. Jones, "Differentiated Services
(Diffserv) and Real-Time Communication", RFC 7657,
DOI 10.17487/RFC7657, November 2015,
<https://www.rfc-editor.org/info/rfc7657>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8169] Mirsky, G., Ruffini, S., Gray, E., Drake, J., Bryant, S.,
and A. Vainshtein, "Residence Time Measurement in MPLS
Networks", RFC 8169, DOI 10.17487/RFC8169, May 2017,
<https://www.rfc-editor.org/info/rfc8169>.
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Appendix A. Example of DetNet data plane operation
[Editor's note: Add a simplified example of DetNet data plane and how
labels etc work in the case of MPLS-based PSN and utilizing PREOF.
The figure is subject to change depending on the further DT decisions
on the label handling..]
Appendix B. Example of pinned paths using IPv6
TBD.
Authors' Addresses
Jouni Korhonen (editor)
Email: jouni.nospam@gmail.com
Balazs Varga (editor)
Ericsson
Magyar Tudosok krt. 11.
Budapest 1117
Hungary
Email: balazs.a.varga@ericsson.com
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