Network Working Group Z. Li
Internet-Draft S. Peng
Intended status: Standards Track Huawei Technologies
Expires: March 11, 2021 D. Voyer
Bell Canada
C. Xie
China Telecom
P. Liu
China Mobile
Z. Qin
China Unicom
K. Ebisawa
Toyota Motor Corporation
S. Previdi
Individual
J. Guichard
Futurewei Technologies Ltd.
September 7, 2020
Problem Statement and Use Cases of Application-aware Networking (APN)
draft-li-apn-problem-statement-usecases-01
Abstract
Network operators are facing the challenge of providing better
network services for users. As the ever developing 5G and industrial
verticals evolve, more and more services that have diverse network
requirements such as ultra-low latency and high reliability are
emerging, and therefore differentiated service treatment is desired
by users. However, network operators are typically unaware of which
applications are traversing their network infrastructure, which means
that only coarse-grained services can be provided to users. As a
result, network operators are only evolving their infrastructure to
be large but dumb pipes without corresponding revenue increases that
might be enabled by differentiated service treatment. As network
technologies evolve including deployments of IPv6, SRv6, Segment
Routing over MPLS dataplane, the programmability provided by IPv6 and
Segment Routing can be augmented by conveying application related
information into the network. Adding application knowledge to the
network layer allows applications to specify finer granularity
requirements to the network operator.
This document analyzes the existing problems caused by lack of
application awareness, and outlines various use cases that could
benefit from an Application-aware Networking (APN) architecture.
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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 [RFC2119].
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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 March 11, 2021.
Copyright Notice
Copyright (c) 2020 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
Provisions Relating to IETF Documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Large but Dumb Pipe . . . . . . . . . . . . . . . . . . . 4
3.2. Network on Its Own . . . . . . . . . . . . . . . . . . . 4
3.3. Decoupling of Network and Applications . . . . . . . . . 5
3.4. Challenges of Traditional Differentiated Service
Provisioning . . . . . . . . . . . . . . . . . . . . . . 5
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3.5. Challenges of Supporting New 5G and Edge Computing
Technologies . . . . . . . . . . . . . . . . . . . . . . 6
4. Key Elements of Application-aware Networking (APN) . . . . . 6
4.1. Use cases for Application-aware Networking (APN) . . . . 8
4.1.1. Application-aware SLA Guarantee . . . . . . . . . . . 8
4.1.2. Application-aware network slicing . . . . . . . . . . 8
4.1.3. Application-aware Deterministic Networking . . . . . 9
4.1.4. Application-aware Service Function Chaining . . . . . 10
4.1.5. Application-aware Network Measurement . . . . . . . . 10
5. Application-aware IPv6 Networking (APN6) . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
Due to the requirement for differentiated traffic treatment driven by
diverse new services, the ability to convey the characteristics of an
application's traffic flow and program the network infrastructure
accordingly to provide fine-grained service assurance is becoming
increasingly necessary for network operators. The Application-aware
Networking (APN) architecture is being defined to address the
requirements and use cases described in this document. APN takes
advantage of network programmability by conveying application related
information in the data plane allowing applications to specify finer
grained requirements to the network infrastructure.
2. Terminology
ACL: Access Control List
APN: Application-aware Networking
APN6: Application-aware Networking for IPv6/SRv6
DPI: Deep Packet Inspection
PBR: Policy Based Routing
QoE: Quality of Experience
SDN: Software Defined Networking
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SLA: Service Level Agreement
MPLS: Multiprotocol Label Switching
SR: Segment Routing
SRv6: Segment Routing over IPv6 dataplane
SR-MPLS: Segment Routing over MPLS dataplane
VPN: Virtual Private Network
TE: Traffic Engineering
FRR: Fast Reroute
CAPEX: Capital expenditures
OPEX: Operating expenditures
3. Problem Statement
This section summarizes the challenges currently faced by network
operators when attempting to provide fine-grained traffic operations
to satisfy the various application-awareness requirements demanded by
new services that require differentiated service treatment.
3.1. Large but Dumb Pipe
In today's networks, the infrastructure through which user traffic is
forwarded is not able to determine information about the packet,
including which application the traffic belongs to, without the
introduction of middleware such as DPI, that is, the network and
applications are decoupled. It is therefore difficult for network
operators to provide fine-grained traffic operations for performance-
demanding applications. In order to satisfy the SLA requirements
network operators continue to increase the network bandwidth but only
carrying very light traffic load (around 30%-40% of its capacity).
This situation greatly increases the CAPEX and OPEX but only brings
very little revenue from the carried services.
3.2. Network on Its Own
As the network evolves, technologies such as VPN, TE, FRR, SFC,
Network Slicing, etc play important roles in satisfying service
isolation, SLA guarantee, and high reliability, etc. These network
technologies have themselves been evolving, introducing new features
that forces the network operator to be continuously upgrading their
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network infrastructure. However, none of these network technologies
make the network aware of which application traffic belongs to and
the fine granularity requirements of the application. Therefore,
such continuous network infrastructure upgrade doesn't always enable
true fine-grained traffic operation, therefore reducing the ability
to bring corresponding revenue increase.
3.3. Decoupling of Network and Applications
MPLS played a very important role in helping the network enter the
generation of All-IP successfully. However, MPLS alone doesn't allow
a close interworking with the application layer since MPLS
encapsulation is, typically, not used by the packet source.
As new services continuously evolve, more encapsulations are
required, and this isolation and decoupling has further become the
blockage towards the seamless convergence of the network and
applications.
3.4. Challenges of Traditional Differentiated Service Provisioning
Several IETF activities have been reviewed which are primarily
intended to evolve the IP architecture to support new service
definitions which allow preferential or differentiated treatment to
be accorded to certain types of traffic. The challenge when using
traditional ways to guarantee an SLA is that the packets are not able
to carry enough information for indicating applications and
expressing their service/SLA requirements. The network devices
mainly rely on the 5-tuple of the packets or DPI. However, there are
some challenges for these traditional methods in differentiated
service provisioning:
1. Five Tuples used for ACL/PBR: five tuples are widely used for
ACL/PBR matching of traffic. However, these features cannot
provide enough information for the fine-grained service process,
and can only provide indirect application information which needs
to be translated in order to indicate a specific application.
2. Deep Packet Inspection (DPI): If more information is needed, it
must be extracted using DPI which can inspect deep into the
packets for application specific information. However, this will
introduce more CAPEX and OPEX for the network operator and impose
security challenges.
3. Orchestration and SDN-based Solution: In the era of SDN,
typically, an SDN controller is used to manage and operate the
network infrastructure and orchestrator elements introduce
application requirements so that the network is programmed
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accordingly. The SDN controller can be aware of the service
requirements of the applications on the network through the
interface with the orchestrator, and the service requirement is
used by the controller for traffic management over the network.
However, this method raises the following problems:
A. The whole loop is long and time-consuming which is not
suitable for fast service provisioning for critical
applications;
B. Too many interfaces are involved in the loop, as shown in
Figure 1, which introduce challenges of standardization and
inter-operability.
+--------------+
+-----| Orchestrator | -------------------+
| +--------------+ Resource |
APP Req. | | Management |
+---------+ +---------+ & +---------+
|SDN Ctrl1| |SDN Ctrl2| Service |SDN Ctrl3|
+---------+ +---------+ Provisioning +---------+
App Req./ | | \ | \
/ | | \ | \
/ | | \ | \
+---+ +-----+ +--------+ +-------+ +-------+ +-------+
|APP| | DCN | |Network |..|Network| |Network|..|Network|
+---+ +-----+ | D1 | | D3 | | D4 | | D6 |
+--------+ +-------+ +-------+ +-------+
Figure 1: Multiple interfaces involved in the long service-
provisioning loop
3.5. Challenges of Supporting New 5G and Edge Computing Technologies
New technologies such as 5G, IoT, and edge computing, are
continuously developing leading to more and more new types of
services accessing the network. Large volumes of network traffic
with diverse requirements such as low latency and high reliability
are therefore rapidly increasing. If traditional methods for
differentiation of traffic continue to be utilized, it will cause
much higher CAPEX and OPEX to satisfy the ever-developing
applications' diverse requirements.
4. Key Elements of Application-aware Networking (APN)
Application-aware Networking (APN) aims to address the problems
mentioned in Section 3, associated with fine-grained traffic
operations that are required in order to satisfy the various
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application-awareness requirements demanded by new services that need
differentiated service treatment. APN aims to implement a mechanism
through which application information is conveyed into the network
infrastructure and that describes characteristics of the application
associated with a traffic flow (e.g., application identification,
network performance requirements), allowing the network to quickly
adapt and perform the necessary resource adjustments so to maintain
SLA performance guarantees, and hence better serve application fine-
grained service requirements.
APN has the following key elements:
1. Application information is conveyed in the data plane through
augmentation of existing encapsulations such as IPv6, SRv6 and
MPLS. The conveyed application characteristic information
(application-aware information) includes application
identification and/or its network performance requirements. This
element is not intended to be enforced but rather it provides an
open option for applications to decide whether to input this
application-aware information into their data stream. When a
data packet uses APN and conveys the application information, it
is referred in this document as an APN packet.
2. Application information and network service provisioning matching
providing fine-granularity network service provisioning (traffic
operations) and SLA guarantee based on the application-aware
information carried in APN packets. This element provides the
network capabilities to applications. According to the
application-aware information, appropriate network services are
selected, provisioned, and provided to the demanding applications
to satisfy their performance requirements.
3. Network measurement of network performance and update the match
between the applications and corresponding network services for
better fine-granularity SLA compliance. The network measurement
methods include in-band and out-of-band, passive, active, per-
packet, per-flow, per node, end-to-end, etc. These methods can
also be integrated.
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Applications | Network
Element 1: Conveying ------------------->
/|\
Application Info | Network capabilities
| (SLA guarantee)
| /|\
Element 2: Matching |
|
Element 3: Network Measurement
Figure 2: Illustration of the key elements of APN
4.1. Use cases for Application-aware Networking (APN)
This section provides the use cases that can benefit from the
application awareness introduced by APN. The corresponding
requirements for APN are also outlined.
4.1.1. Application-aware SLA Guarantee
One of the key objectives of APN is for network operators to provide
fine-granularity SLA guarantees instead of coarse-grain traffic
operations. This will enable them to provide differentiated services
for different applications and increase revenue accordingly. Among
various applications being carried and running in the network, some
revenue-producing applications such as online gaming, video
streaming, and enterprise video conferencing have much more demanding
performance requirements such as low network latency and high
bandwidth. In order to achieve better Quality of Experience (QoE)
for end users and engage customers, the network needs to be able to
provide fine-granularity and even application-level SLA guarantee.
Differentiated service provisioning is also desired.
The APN architecture MUST address the following requirements:
o APN needs to perform the three key elements as described in
Section 4.
o Support application-level fine-granularity traffic operation that
may include finer QoS scheduling.
4.1.2. Application-aware network slicing
More and more applications/services with diverse requirements are
being carried over and sharing the network operators' network
infrastructure. However, it is still desirable to have customized
network transport that can support some application's specific
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requirements, taking into consideration service and resource
isolation, which drives the concept of network slicing.
Network slicing provides ways to partition the network infrastructure
in either the control plane or data plane into multiple network
slices that are running in parallel. These network slices can serve
diverse services and fulfill their various requirements at the same
time. For example, the mission critical application that requires
ultra-low latency and high reliability can be provisioned over a
separate network slice.
The APN architecture MUST address the following requirements:
o APN needs to perform the three key elements as described in
Section 4 in the context of network slicing.
o For the element 2, the APN architecture MUST allow to assign a
given traffic flow to specific network slice according to the
application information carried in the APN packet.
o For the element 3, the APN architecture MUST allow the network
measurement of each network slice.
4.1.3. Application-aware Deterministic Networking
[RFC8578] documents use cases for diverse industry applications that
require deterministic flows over multi-hop paths. Deterministic
flows provide guaranteed bandwidth, bounded latency, and other
properties relevant to the transport of time-sensitive data, and can
coexist on an IP network with best-effort traffic. It also provides
for highly reliable flows through provision for redundant paths.
The APN architecture MUST address the following requirements:
o APN needs to perform the three key elements as described in
Section 4 in the context of deterministic networking.
o For the element 2, the APN architecture MUST allow to assign a
given traffic flow to a specific deterministic path according to
the application information carried in the APN packet.
o For the element 3, the APN architecture MUST allow the network
measurement of each application-aware deterministic path.
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4.1.4. Application-aware Service Function Chaining
End-to-end service delivery often needs to go through various service
functions, including traditional network service functions such as
firewalls, DPIs as well as new application-specific functions, both
physical and virtual. The definition and instantiation of an ordered
set of service functions and subsequent steering of the traffic
through them is called Service Function Chaining (SFC) [RFC7665].
SFC is applicable to both fixed and mobile networks as well as data
center networks.
Generally, in order to manipulate a specific application traffic
along the SFC, a DPI needs to be deployed as the first service
function of the chain to detect the application, which will impose
high CAPEX and consume long processing time. For encrypted traffic,
it even becomes impossible to inspect the application.
The APN architecture MUST address the following requirements:
o APN needs to perform the three key elements as described in
Section 4 in the context of service function chaining.
o For the element 1, class information can be conveyed.
o For the element 2, the APN architecture MUST allow to assign a
given traffic flow to a specific service function chain and MUST
allow the subsequent steering according to the application
information carried in the APN packets.
o For the element 3, the APN architecture MUST allow the network
measurement of each application-aware service function chain.
4.1.5. Application-aware Network Measurement
Network measurement can be used for locating silent failure and
predicting QoE satisfaction, which enables real-time SLA awareness/
proactive OAM. Operations, Administration, and Maintenance (OAM)
refers to a toolset for fault detection and isolation, and network
performance measurement. In-situ Operations, Administration, and
Maintenance (IOAM) records operational and telemetry information in
the packet while the packet traverses a path between two points in
the network.
The APN architecture MUST address the following requirements:
o APN needs to perform the two key elements as described in
Section 4 in the context of network measurement. The network
measurement in the element 3 does not need to be considered here.
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5. Application-aware IPv6 Networking (APN6)
As mentioned in Section 3.3, MPLS dataplane is not (or rarely) used
at the packet origin (i.e., where the packet is sourced) and
therefore it is not possible to assume the MPLS encapsulation is
available end-to-end in the traffic flow journey. This scenario is
still supported by APN with the ability to classify the packet at the
ingress node of the MPLS domain. Of course, it reduces the seamless
inter-working between applications and network layer but still APN
will improve the resources utilization of the network layer.
APN is intended to be dataplane agnostic. Hence, APN architecture,
functions and elements are applicable to both IPv6/SRv6 and MPLS
dataplanes. However, it is obvious that IPv6/SRv6 dataplane delivers
a better option for APN due to its flexibility, address space and
later developments of SRv6 as of
[I-D.ietf-6man-segment-routing-header] and
[I-D.ietf-spring-srv6-network-programming]. Therefore, this document
is mostly focused on the IPv6/SRv6 dataplane. MPLS dataplane is also
supported by APN but with some limitations such as backward
compatibility and limited address space (20 bits label size).
In this document we refer to APN6 when APN applies to the IPv6/SRv6
dataplane. Application-aware IPv6 Networking (APN6) aims to address
APN problems described in Section 3 in the IPv6/SRv6 dataplane. APN6
conveys information into the network infrastructure about the
characteristics of the application associated with a traffic flow
(including application identification and network performance
requirements), using IPv6/SRv6 encapsulation allowing the network to
quickly adapt and perform the necessary network resource adjustments
to maintain SLA performance guarantees, and hence better serve
application fine-grained service requirements.
The advantages of using IPv6/SRv6 to support APN include,
1. Simplicity: Conveying application information with IPv6
encapsulation can just be based on IP reachability.
2. Seamless convergence: Much easier to achieve seamless convergence
between applications and network since both are based on IPv6.
3. Great extensibility: IPv6 encapsulation including its extension
headers can be used to carry very rich information relevant to
applications.
4. Backward compatibility: On-demand network upgrade and service
provisioning. If the application information is not recognized
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by the node, the packet will be forwarded based on pure IPv6,
which ensure backward compatibility.
5. Little dependency: Information conveying and service provisioning
are only based on the forwarding plane of devices, which is
different from the Orchestration and SDN-based solution which
involves multiple elements and diverse interfaces.
6. Quick response: Flow-driven and direct response from devices
since it is based on the forwarding plane.
6. IANA Considerations
This document does not include an IANA request.
7. Security Considerations
Since the application information is conveyed into the network, it
does involve some security and privacy issues.
First, APN only provides the capability to the applications to
provide their profiles and requirements to the network, but it leaves
the applications to decide whether to input this information. If the
applications decide not to provide any information, they will be
treated in the same way as today's network and cannot get the
benefits from APN.
Once the application information has been carried in the IPv6 packets
and conveyed into the network, the IPv6 extension headers, AH and
ESP, can be used to guarantee the authenticity of the added
application information.
Any scheme involving an information exchange between layers
(application and network layers in this case) will obviously require
an accurate valuation of security mechanism in order to prevent any
leak of critical information. Some additional considerations may be
required for multi-domain use cases. For example, how to agree upon
which application information/ID to use and guarantee authenticity
for packets traveling through multiple domains (network operators).
8. Acknowledgements
The authors would like to acknowledge Robert Raszuk (Bloomberg LP)
and Yukito Ueno (NTT Communications Corporation) for their valuable
review and comments.
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9. Contributors
Daniel Bernier
Bell Canada
Canada
Email: daniel.bernier@bell.ca
Liang Geng
China Mobile
China
Email: gengliang@chinamobile.com
Chang Cao
China Unicom
China
Email: caoc15@chinaunicom.cn
Chang Liu
China Unicom
China
Email: liuc131@chinaunicom.cn
Cong Li
China Telecom
China
Email: licong@chinatelecom.cn
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
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[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>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>.
10.2. Informative References
[]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-18 (work in
progress), August 2020.
Authors' Addresses
Zhenbin Li
Huawei Technologies
China
Email: lizhenbin@huawei.com
Shuping Peng
Huawei Technologies
China
Email: pengshuping@huawei.com
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
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Chongfeng Xie
China Telecom
China
Email: xiechf@chinatelecom.cn
Peng Liu
China Mobile
China
Email: liupengyjy@chinamobile.com
Zhuangzhuang Qin
China Unicom
China
Email: qinzhuangzhuang@chinaunicom.cn
Kentaro Ebisawa
Toyota Motor Corporation
Japan
Email: ebisawa@toyota-tokyo.tech
Stefano Previdi
Individual
Italy
Email: stefano@previdi.net
James N Guichard
Futurewei Technologies Ltd.
USA
Email: jguichar@futurewei.com
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