Internet DRAFT - draft-dang-detnet-deployment
draft-dang-detnet-deployment
DetNet J. Dang, Ed.
Internet-Draft Huawei
Intended status: Informational Z. Du
Expires: 12 April 2022 China Mobile
L. Li, Ed.
Huawei
9 October 2021
Services Deployment Guideline in DetNet Network
draft-dang-detnet-deployment-01
Abstract
Deterministic Networking (DetNet) defined in [RFC8655] provides a
capability for the delivery of data flows with extremely low packet
loss rates and bounded end-to-end delivery latency. DetNet network
administrators worldwide can deploy DetNet services into their
networks. This document aims to provide a guideline for DetNet
network administrators.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 12 April 2022.
Copyright Notice
Copyright (c) 2021 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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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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extracted from this document must include Simplified BSD License text
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provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Terminology & Abbreviations . . . . . . . . . . . . . . . . . 3
4. Preparation and Planning of DetNet networks . . . . . . . . . 3
4.1. Collecting and Planning information of DetNet system . . 4
4.2. Collecting and Planning parameters of DetNet service and
DetNet flow . . . . . . . . . . . . . . . . . . . . . . . 4
4.2.1. Explicit Path and Service Protection . . . . . . . . 5
4.2.2. Encapsulation Type of Networking Technology . . . . . 5
4.2.3. Type of Queuing Mechanism . . . . . . . . . . . . . . 6
4.3. DetNet Resource Evaluation . . . . . . . . . . . . . . . 6
4.3.1. DetNet Bandwidth Evaluation and Reservation . . . . . 7
4.3.2. DetNet Latency Evaluation . . . . . . . . . . . . . . 8
4.3.3. DetNet Jitter Evaluation . . . . . . . . . . . . . . 8
5. Controller Processing and Operation . . . . . . . . . . . . . 8
6. Performed Functions on DetNet Network Node . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Normative References . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
Deterministic Networking (DetNet) defined in [RFC8655] provides a
capability for the delivery of data flows with extremely low packet
loss rates and bounded end-to-end delivery latency. The diverse
industries in [RFC8578] have in common a need for "deterministic
flows". How to introduce deterministic flows to the DetNet network
is required.
While the DetNet technologies are becoming mature, it's the right
time for DetNet deployment to do the live network experiments and
even large-scale commercial deployments. The DetNet network is
actively managed by a network operations entity (the "administrator",
whether a single person or a department of administrators). A
network administrator is responsible for the deployment of DetNet
services, who can must master the skills of how to introduce
deterministic flows into DetNet networks and the related maintenance.
This document is intended as guidance for DetNet network
administrators. And the DetNet network belongs to the L3 layer
network.
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The processes of consists of deployment preparation, planning and
configuration. Session 4 illustrates what information needs to be
collected and how to use them and how to input the collected
parameters into the network planning system. In session 5, the
controller executes the operation instructions to generate
configurations and even calculates specific explicit paths. Session
6 and the network element node performs configuration and path
information received from the controller.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
3. Terminology & Abbreviations
DetNet UPE
A DetNet edge node, which connects DetNet flows into DetNet network.
DetNet P
A DetNet relay node or DetNet transit node.
DetNet PE
A DetNet edge node, where DetNet flows leave DetNet network.
DetNet source
An end system is capable of originating a DetNet flow.
DetNet Destination
An end system is capable of terminating a DetNet flow.
4. Preparation and Planning of DetNet networks
Before deployment, a DetNet network administrator must first fully
understand the concept of DetNet service defined in session 4.3 of
RFC 8655, DetNet flow defined in RFC 9016, and explicit route defined
in defined in session 3.2.3 of RFC8655. The essence of DetNet
service deployment is to map the DetNet service to the corresponding
DetNet flow, and then use the relevant explicit path to transmit on
the network.
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Next, the DetNet network administrator must investigate and
understand the status of the network. After that she/he should input
the information collected onto the DetNet planning tool, which may be
integrated in the controller or appears as an independent system.
The DetNet planning tool should have a certain degree of automation
capabilities.
In this document, we do not introduce the connectivity deployment
(such as IGP, BGP) of the basic network, and assume that the basic
network connections are ready.
4.1. Collecting and Planning information of DetNet system
The DetNet network administrator must figure out the related DetNet
system where DetNet service to be deployed. The DetNet system should
include DetNet Edge and Transit Nodes, which node the DetNet flow
will passes through via explicit paths. The DetNet network
administrator must know the specific location of the relevant network
nodes of DetNet system, which should be single-domain or cross-
domain. If the DetNet network is cross-domain, some Transit Nodes
may also perform the functions of ASBR.
4.2. Collecting and Planning parameters of DetNet service and DetNet
flow
The DetNet network administrator should collect the parameters of
DetNet service and DetNet flow.
According to session 6 of RFC 9016, the management ID, delivery type,
delivery profile, connectivity type and BiDir requirement and rank of
the Detnet services should be collected.
According to session 5 of RFC9016, the management ID, payload type,
format, identification and specification, endpoints, rank,
requirement and BiDir Requirement of the Detnet flows should be
collected. The flow identification for MPLS and IP Data Planes are
described in [RFC8939] , [RFC8964], and Ethernet information (such as
MAC address, VLAN) respectively.
The DetNet network administrator must plan how to map the DetNet
services into a DetNet flow. If a DetNet service wants to join
DetNet flow, the premise is that the encapsulation types of both of
them must be the same and DetNet Edges to be used are same. About
the encapsulation types, that is, the Delivery Type of the DetNet
Service must be equal to the Payload Type of the DetNet Flow. Then
it is necessary to determine whether the Requirements of the DetNet
Flow can meet the requirements of the Delivery Profile of the DetNet
Service. First, it is seen if MaxLatency, MaxLatencyVariation,
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MaxLoss, MaxConsecutiveLossTolerance, MaxMisordering are satisfied.
If they are satisfied, it is judged whether MinBandwidth can be
satisfied. The above work should be done using automation functions.
It is finally determined that the DetNet services will join a DetNet
flow, then a Management ID of the DetNet Flow is assigend to this
DetNet services. To explain further, Management ID of the DetNet
Flow, which is a unique identifier for identifying each DetNet flow,
can be used to define the N:1 mapping of DetNet flows to a DetNet
service.
If a DetNet flow deployed needs to be canceled, the network
administrator will execute the corresponding undo operation through
the controller, and the network will release the corresponding
resources.
4.2.1. Explicit Path and Service Protection
In the follow-up work, the DetNet network administrator creates
explicit route defined in section 3.2.3 of [RFC8655] according to the
information which node the DetNet flow is accessed from and which
node the DetNet flow leaves from.
The endpoints, where the Detnet service will access to and explicit
paths will be running between, must be within the scope of the DetNet
system. Based on the endpoints of the DetNet flow, the related
DetNet Ingress PE and Egress PE are determined. The DetNet Ingress
PE and Egress PE can run more than one explicit path to implement
service protection and reordering on DetNet Edge nodes.
The DetNet network administrator can consider how to do with service
protection to meet MaxLoss, MaxConsecutiveLossTolerance and
MaxMisordering of a deterministic flow. The premise of service
protection is that there are multiple available explicit paths for a
DetNet flow. These types of packet loss can be greatly reduced by
spreading the data over multiple disjointed forwarding paths. The
PREOF embeded in the PE node ensures that packets are not out of
order.
4.2.2. Encapsulation Type of Networking Technology
The DetNet network administrator must pay attention to the
encapsulation type of the explicit route, which is added to the
DetNet flows when DetNet flow enters the UPE node. The DetNet
network administrator may freely choose encapsulation type of the
networking technology according to his/her preferences. The way of
IP over SR or [IP-Over-MPLS] or IP over SR is recommended.
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4.2.3. Type of Queuing Mechanism
Based on the traffic specification and rank of the DetNet flow, the
buffer settings of the queue, including Guaranteed-Service IntServ,
Cyclic Queuing and Forwarding and so on, need to refer to Internal,
MaxPacketsPerInterval, MaxPayloadSize, MinPacketsPerInterval and
DnFlowRank within them.
The DetNet network administrator obtains or sets the queuing type
used by the network. For examplem, if the cyclic queuing mechanism
is used in the network, the parameters of the queuing. This
mechanism must allow multiple deterministic flows to share a periodic
buffer.
* CyclicBufferSize: the length of the cyclic buffer
* CyclicInterval: duration of periodic scheduling
* BufferNumber: the number of the cyclic buffer
* MinBurstSize: the minimum burst size that can be tolerated by
cyclic queue mechanism, which is specified in octets per second
and excludes additional DetNet header (if any).Bandwidth used
above the Committed Information rate is called Burst traffic. It
is used when the bandwidth available is more than CIR.
MinBurstSize is the minimum burst size that has to be guaranteed
for the DetNet traffic. The queuing mechanism needs to pay
attention to how to shape burst size traffic into buffers.
4.3. DetNet Resource Evaluation
The DetNet network administrator can enable network resource
evaluation and reservation of the controller. The requirements of
DetNet flow in section 5.9 of [RFC9016] include MinBandwidth,
MaxLatency, MaxLoss, MaxConsecutiveLossTolerance and MaxMisordering.
If the deterministic flow has requirement for Jitter, a new parameter
named jitter needs to be added.
In fact, the network may support a distributed protocol similar to
RSVP defined in [draft-trossen-detnet-rsvp-tsn], so this function can
rely on the distributed protocol.
Based on Requirements of DetNet flow, the resource reservation
algorithm must completely satisfy them. Regarding MaxLatency, there
are different precision degree of mechanisms, one is to seek a
maximum degree of approximation, the other is to ensure accuracy.
The CFQ mechanism is recommended when resource reservation works
well.
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The DetNet SLA requirements to the DetNet flow generally have
deterministic bandwidth, bounded latency and bounded jitter. But in
fact these three parameters are interrelated. For example, the
insufficient bandwidth reservation might introduce the additional
delay or the additional jitter. Therefore, the bandwidth reservation
should consider the latency and jitter requirements.
There are three methods here to do with, one is to get it through
centralized calculation provided by controller or other centralized
systems, the other is to get it through negotiation between DetNet
Nodes along the explicit routes, and the third is to rely on the
human brain. When the scale of the network becomes larger or the
types of services become more, the third method is difficult to
handle. Therefore, the first and the second methods are recommended.
These centralized and distributed solutions can cooperate with each
other, for example, if the centralized system is offline, the
distributed system functions will be enabled. Or in order to support
rapid network decision-making, the priority is given to using
distributed systems for deployment, and the centralized systems are
responsible for global optimization.
The algorithm on the network resource reservation is not discussed
now in this document.
4.3.1. DetNet Bandwidth Evaluation and Reservation
The DetNet network administrator must know the bandwidth resource
evaluation and reservation can be divided into service access
interface part on the DetNet UPE node and explicit route part.
* Service access interface part on the DetNet UPE node: The
bandwidth of service access interface part on the DetNet UPE is
reserved according to the MinBandwidth of the DetNet flow.
* Explicit route part: This mechanism ensures that the available
bandwidth along the explicit path can meet MinBandwidth of DetNet
flow.
The P node should take into account that there are multiple explicit
routes passing in the same direction. For example, if one interface
of P node accesses 3 explicit paths, the reserved bandwidth of the
interface is the total required bandwidth of the 3 explicit paths.
It is emphasized that the remaining bandwidth of the interface on the
DetNet nodes can also be used for non-DetNet flows.
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4.3.2. DetNet Latency Evaluation
The DetNet network administrator can let the controller collect the
network-wide delay information for calculation and evaluation, and
obtain the queuing type.
Given that DetNet nodes have a finite amount of buffer space, the
resource allocation necessarily results in a maximum end-to-end
latency. The overall latency of the explicit route can be calculated
based on the queue scheduling mechanism on the data plane of the
DetNet nodes. The queue scheduling mechanisms have various types,
such as DiffServ,Qch[IEEE802.1QCH] and so on.
[DetNet-Bounded-Latency] provides end-to-end delay bound and backlog
bound computations for such mechanisms that can be used by the
control plane to provide DetNet QoS. If the CQF is used,
CyclicBufferSize, CyclicInterval and BufferNumber of queuing
mechanism can be included in the calculation factors that affect the
E2E delay.
The controller evaluates the path delay based on the resources of the
entire network, and judges whether it meets the MaxLatency of the
deterministic flow.
4.3.3. DetNet Jitter Evaluation
The DetNet network administrator can figure out that there are two
aspects to reduce network jitter. The first is through resource
reservation in section 4.4.1 to 4.4.2 , and the second is through
effective queuing control methods. The former is not easy to
evaluate jitter, but the latter is very convenient. The DetNet
network administrator also can know the queuing type, because not all
queuing mechanisms have a jitter control mechanism. The CQF is
recommend to effectively solve the uncertainty of jitter. Under this
mechanism, the end to end jitter can be controlled within 2 *
CyclicInterval.
5. Controller Processing and Operation
The DetNet network administrator should let the planning tool connect
to DetNet controller defined in draft-ietf-detnet-controller-plane-
framework ,or the planning tool should automatically to notisfy the
DetNet controller after the work finised in the planning tool. As
draft-ietf-detnet-controller-plane-framework describes, the DetNet
control plane is responsible for the instantiation and maintenance of
DetNet services and DetNet flows and explicit path, for the functions
of resource reservation, path caculation and service protection.
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Finally, the DetNet controller should generate configuration and path
information and download them on demand to the related DetNet network
nodes.
After the information is input by the DetNet network administrator,
the controller will convert the information into the network
configuration and send it to the DetNet network element node, using a
protocol such as NETCONF [RFC6241]/YANG[RFC6020]. Deterministic
Networking (DetNet) YANG Model defined in [DetNet-YANG] contains the
specification for the Deterministic Networking YANG Model for
configuration and operational data for DetNet Flows.
6. Performed Functions on DetNet Network Node
The DetNet network administrator should check the operation of the
DetNet network nodes.
The dynamic signaling protocols most commonly used for label
distribution are LDP [RFC5036], RSVP-TE, and BGP [RFC8277] (which
enables BGP/ MPLS-based Layer 3 VPNs [RFC4384] and Layer 2 VPNs
[RFC7432]).
After DetNet network node receives the information from the
controller, the function will be executed.
Basic Network Configuration among DetNet Network nodes:
* MPLS TE or Segment Routing configuration RSVP configuration for
resource reservation(optional)
* Configuration Enabling DetNet capability Configuration of Queuing
mechanism
Ingress Node DetNet services Configuration:
* DetNet flow Configuration Explicit path configuration
* Configuration of Mapping DetNet flow to explicit path
Configuration of Service Protection
* Configuration of Queuing mechanism EgressConfiguration of Queuing
mechanism Configuration of Service Protection
Egress Node DetNet services Configuration:
* DetNet flow Configuration Explicit path configuration
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* Configuration of Mapping DetNet flow to explicit path
Configuration of Service Protection
* Configuration of Queuing mechanism EgressConfiguration of Queuing
mechanism Configuration of Service Protection
After DetNet network equipment receives the configuration, it starts
to execute. As Figure 2 is shown, the functions of each DetNet
network element is clearly visible.
SDN +----+ 1.Entrance to the above information
Controller | | 2.Network Resource Evaluation and Reservation(Optional)
+----+ 3.Converting the information into the network configuration
|
+--------+-------+------+
| | | |
+----+ +---+ +---+ +---+
U PE +---+ P +---+...+---+ PE+
+----+ +---+ +---+ +---+
| | |
| | +-->+-----------------------------+
| | |1. Enabling queuing mechanism|
| | |2. End Explicit Path |
| | +-----------------------------+
| +-->+--------------------------+
| |Enabling queuing mechanism|
| +--------------------------+
+--> +-------------------------------------------------------+
|1.Identifying a deterministic flow |
|2.Establishing explicit path for the deterministic flow|
|3.Enabling queuing mechanism |
+-------------------------------------------------------+
Figure-2: DetNet Network Functions
7. Security Considerations
The DetNet network administrator should work accroding to RFC 9055
which addresses security considerations specific to the IP and MPLS
data plane technologies, thereby complementing the Security
Considerations sections of those documents.
8. Normative References
[DetNet-Bounded-Latency]
"DetNet Bounded Latency", <https://www.rfc-
editor.org/info/draft-ietf-detnet-bounded-latency>.
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[DetNet-YANG]
"Deterministic Networking (DetNet) YANG Model",
<https://www.rfc-editor.org/info/draft-ietf-detnet-yang-
12>.
[draft-trossen-detnet-rsvp-tsn]
"RSVP for TSN Networks", <https://www.rfc-editor.org/info/
draft-trossen-detnet-rsvp-tsn>.
[IEEE802.1QCH]
"IEEE Standard for Local and metropolitan area networks--
Bridges and Bridged Networks--Amendment 29: Cyclic Queuing
and Forwarding",
<https://ieeexplore.ieee.org/document/7961303>.
[IP-Over-MPLS]
"DetNet Data Plane: IP over MPLS", <https://www.rfc-
editor.org/info/draft-ietf-detnet-ip-over-mpls>.
[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>.
[RFC3209] "RSVP-TE: Extensions to RSVP for LSP Tunnels",
<https://www.rfc-editor.org/info/rfc3209>.
[RFC6020] "YANG - A Data Modeling Language for the Network
Configuration Protocol (NETCONF)",
<https://www.rfc-editor.org/info/RFC6020>.
[RFC6241] "Network Configuration Protocol (NETCONF)",
<https://www.rfc-editor.org/info/RFC6241>.
[RFC8402] "Segment Routing Architecture",
<https://www.rfc-editor.org/info/RFC8402>.
[RFC8578] "Deterministic Networking Use Cases",
<https://www.rfc-editor.org/info/rfc8578>.
[RFC8655] "Deterministic Networking Architecture",
<https://www.rfc-editor.org/info/rfc8655>.
[RFC8934] "Deterministic Networking (DetNet) Data Plane: MPLS",
<https://www.rfc-editor.org/info/rfc8934>.
[RFC8939] "Deterministic Networking (DetNet) Data Plane: IP",
<https://www.rfc-editor.org/info/rfc8939>.
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[RFC8964] "Deterministic Networking (DetNet) Data Plane: MPLS",
<https://www.rfc-editor.org/info/rfc8964>.
[RFC9016] "Flow and Service Information Model for Deterministic
Networking (DetNet)",
<https://www.rfc-editor.org/info/RFC9016>.
[RFC9023] "Deterministic Networking (DetNet) Data Plane: IP over
IEEE 802.1 Time-Sensitive Networking (TSN)",
<https://www.rfc-editor.org/info/rfc9023>.
Authors' Addresses
Joanna Dang (editor)
Huawei
No.156 Beiqing Road
Beijing
P.R. China, 100095
China
Email: dangjuanna@huawei.com
Zongpeng Du
China Mobile
32 Xuanwumen West St
Beijing
P.R. China, 100053
China
Email: duzongpeng@chinamobile.com
Yizhou (editor)
Huawei
P.R. China,
China
Email: liyizhou@huawei.com
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