Internet DRAFT - draft-zhou-alto-dbors-requirement-usecase
draft-zhou-alto-dbors-requirement-usecase
ALTO F. Zhou
Internet-Draft S. Wang
Intended status: Standards Track D. Yuan
Expires: 25 April 2023 ZTE Corporation
22 October 2022
Requirements and Use Cases of DB-ORS (Database-based Open Resource
Service)
draft-zhou-alto-dbors-requirement-usecase-00
Abstract
This draft introduces the new challenges for the network brought by
massive access services under the background of the convergence of
the cloud and the network which acquires the network to identify and
convey the information of fine-grain user and application
requirements, aiming to fulfill differentiated service provisioning
and improve the comprehensive utilization of network resources. The
draft raises the scope of current solution gap analysis and further
proposes the definition of DB-ORS in which network capabilities are
abstracted as atomic services and can be orchestrated by
applications. Scenarios of cloud access and DCI are outlined to
clarify the concepts and principles of DB-ORS in overcoming
challenges.
Status of This Memo
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Copyright Notice
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Table of Contents
1. Requirement Analysis . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Solution Gap Analysis . . . . . . . . . . . . . . . . . . . . 3
5. Scope of DB-ORS . . . . . . . . . . . . . . . . . . . . . . . 5
6. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Cloud Access Scenario . . . . . . . . . . . . . . . . . . 6
6.2. DCI Scenario . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Requirement Analysis
Currently, network always provides best-effort services for
application endpoints. When the network generally stays a light-
weight load status, most requirements from the clients can be
satisfied within best-effort traffic.
With the rapid development and comprehensive utilization of cloud
computing and mobile Internet, cloud becomes a popular and major
platform for various enterprises and government departments to host
data and applications. Data explosion and massive access to the
cloud have been proved to be an inevitable inclination, resulting in
accelerating growth of traffic traversing through the network domain
to the cloud. Conventional networks which provide carrier-class
connections are confronted with serious challenges which can be
concluded as follows:
Fine-granularity services provisioning :
Conventional networks only provide customers with coarse-grained
connection services. However, massive access services have proposed
different requirements of multiple attributes including network
delays, jitters, and bandwidths. An existing 5-tuple-based network
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service differentiation manner is not able to provide fine-
granularity SLAs satisfying specific requirements. Services which
are insensitive to network qualities may be served overly, however,
diversified and flexible requirements cannot be guaranteed, resulting
in a waste of network resources. Thus, network capabilities should
be orchestrated in accordance with acquired requirements to achieve
fine-granularity services provisioning.
Network resources utilization enhancement :
Since the growth of traffic traversing through the network domain
into the cloud and the accelerating number of deployed, sufficient
network capacity and bandwidth resources are urgently demanded.
However, the network resources are not orchestrated appropriately and
the resource utilization proves to be relatively low for about 30%
-50%. Therefore, enhancing network resources utilization requires
other solutions.
2. 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. Terminology
* DB-ORS: Database-based Open Resource Service
* SRv6: Segment Routing over IPv6
* MPLS: Multi-Protocol Label Switching
* DCI: Data Center Interconnection
4. Solution Gap Analysis
With the increase of cloud services, various applications with
diversity put forward differentiated requirements. Popular
applications such as VR/AR, cloud games, and industrial Internet
require high-quality network experiences. Therefore, quick access to
the cloud has proved to be a basic requirement. Under these
circumstances, cloud service providers always establish multiple POP
access points in different areas to improve the convenience for
clients, and configures MPLS dedicated lines from POP points to the
data center for satisfying network performance. However, existing
problems in the current strategy are clarified below:
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* Complexity in configuration and maintenance.
* Long period of provisioning cycle.
* Access constrained by fixed POP points and dependency on network
operators.
* Coarse-granularity services provisioning.
* SD-WAN: Software Defined Wide Area Network
SD-WAN handles this problem by monitoring the latency of multiple
backup paths by applying a dynamic multipath optimization algorithm,
which enables traffic to be automatically steered into the most
appropriate path at any given time.
However, dynamic multipath optimization algorithms require traffic
detection techniques to obtain information such as bandwidth, delay,
and jitter of multiple reachable paths, so as to support SD-WAN to
implement path orchestration and routing calculation. Accuracy and
immediacy can hardly be guaranteed simply by statistics collected by
current traffic detection techniques. Thus, when instantaneous
jitter occurs on a monitored link, the current traffic is usually
switched over to a standby path, which results in a waste of network
resources. Furthermore, the introduction of network probing schemes
also exerts extra burden on the network.
SD-WAN is also capable of configuring different priorities in
accordance with requirements from the client, and further generate
and publish the corresponding QoS policies to ensure service
delivery. Latency-sensitive traffic such as VoIP and web
conferencing are configured with higher priority and is further
steered into specific paths with better performance, while services
like file backups are assigned lower priority since they are less
time-sensitive and may even result in blocks on network links.
Conventional service identification and diversion policies based on
5-tuple (source IP address, destination IP address, source port,
destination port, and protocol), configured priorities, or VlanID
have respective defects attributed to the lack of fine-granularity
information.
To sum up, the deficiencies of the current solutions lie in the fact
that the network presents a "black box" status for applications,
which results in the failure to make optimal utilization of network
capabilities. Although option-based extensible capabilities of SRv6
are introduced to enhance the perception ability of the network and
Segment List based orchestration methods are performed to extend the
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routing capability, problems stay unsolved since the cloud and the
network are administered independently and SRv6 policies can not
traverse the boundaries between different domains.
Under current circumstances, besides bandwidth resources, the network
is granted with multiple capabilities such as deterministic
capability, service function chaining, and network slicing. Suppose
the network exposes these capabilities as services and is assisted
with the programmable abilities by SRv6, applications which subscribe
a specific service can orchestrate these services of the network.
With the network capabilities abstracted and services subscription,
the utilization of the entire network resources can be greatly
improved and the applications can be served in a fine-granularity
manner.
5. Scope of DB-ORS
Definitions of network capabilities, such as bandwidth link,
determinism, security abilities, and network slicing, methods to open
these abilities and to subscribe the services are covered and
included in the framework of DB-ORS, aiming to enable applications to
understand the current "black box" status of the network domain.
Implementations and components in DB-ORS include network capabilities
abstraction, service subscription and service orchestration.
* Network capabilities abstraction: Abstract the information
including underlay network topology, delay, bandwidth, and
deterministic attributes, end-to-end service determinism of the
network for instance.
* Network service publication and subscription: Network services are
abstracted in a key-value scheme to a distributed database while
applications can subscribe specific services in need.
* Network service orchestration: Third party devices, controllers,
or orchestrators can be informed of the updated information of
corresponding services from the distributed database and further
orchestrates the services.
6. Use Cases
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6.1. Cloud Access Scenario
As shown in Figure 1, suppose APP1 has strict requirements of low
network delay while APP2 can tolerate relatively unsatisfied network
conditions. The traffic from APP2 traverses the underlay network and
reaches the data center through the edge device. Ideally, traffic
from APP1 is steered into underlay network 1 to cloud gateway of
SaaS_A1 since the network path of underlay network 1 has low latency
and high bandwidth. For APP2, traffic is commonly steered into
SaaS_A2. However, the mentioned scheduling strategy is difficult to
fulfill by existing issues. With the introduction of DB-ORS and SRv6
policies, not only the traffic from APP1 can be steered to
corresponding cloud gateway along the underlay network 1, but also
the traffic from APP2 can be guided with the identical path when
network resources are sufficient in network 1, thus improving the
resource utilization. Suppose underlay network 1 experiences a short
jitter and delay of the path increases, to ensure the access
experience of the APP1, on one hand, traffic from APP1 is switched to
a standby path, and at the same time, traffic from APP2 is switched
immediately to another data center along the path of underlay network
2. In conclusion, the framework of DB-ORS improves the utilization
of network resources in cloud access scenarios.
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.-----. .-----.
( ) ( )
.--( )--. .--( )--.
( ) ( )
( SaaS_A1 ) ( SaaS_A2 )
( ) ( )
( ) ( )
.-----------------. .-----------------.
^ ^
| |
| |
+-----+-----+ +--------------+ +-----+-----+
| gateway +<--------+ Orchestrator +-------->+ gateway |
+-----+-----+ +---+---+---+--+ +-----+-----+
^ | | | ^
| +----------+ | | | +----------+ |
| | database +<-+ | +->+ database | |
.-----. +----^-----+ | +----^-----+ .-----.
( ) | | | ( )
.--( )-----+ v +-----( )--.
( ) +------+ ( )
( underlay network1 )<--------+ edge |-------->( underlay network2 )
( ) +------+ ( )
.--( )--. ^ ^ .--( )--.
( ) | | ( )
.-----. | | .-----.
| |
+-------+ | | +-------+
| APP_1 +--+ +--+ APP_2 |
+-------+ +-------+
Figure 1: Cloud Access Scenario
6.2. DCI Scenario
In order to achieve high availability and better access performance
of services, SaaS providers usually deployed multiple data centers
among distributed regions, districts or cities and thus data
synchronization between remote data centers proves to be
indispensable. Commonly, dedicated lines are configured between data
centers to ensure network quality. Furthermore, attempts are made to
avoid remote accessing services from different places. MPLS
dedicated lines are relatively costly, and the period of service
deployment and provisioning is comparatively long. In addition,
delays, packet losses and interruptions also still occur. Enhancing
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and improving infrastructures blindly or expanding the bandwidth of
configured dedicated line may give rise to a waste of resources. The
granularity for processing services can not achieved only based on
conventional 5-tuple-based methods. As shown in Figure 2, with the
introduction of DB-ORS, previously organized network atomic services
are written into distributed databases. The cloud controllers
subscribe accordingly, so that the logical topology (including
network paths and relevant information of latency and bandwidth) of
interconnections between data centers can be grasped. Network paths
can be re-orchestrated and binded in accordance with fine-granularity
services, achieving differentiated service provisioning.
+------------+
+----->+ database +<-----+
| +------------+ |
| |
| |
| |
| .--------.
.-----. ( ) .-----.
( ) .--( )--. ( )
.--( )--. ( SRv6 Core ) .--( )--.
( ) ( ) ( )
( SaaS_A1 )------( DCI Network )------( SaaS_A2 )
( ) .--( )--. ( )
.---------------. ( ) .---------------.
.--------.
Figure 2: DCI Scenario
7. Security Considerations
TBA
8. Acknowledgements
TBA
9. IANA Considerations
TBD.
10. Normative References
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[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>.
[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>.
Authors' Addresses
Fenlin Zhou
ZTE Corporation
No.50 Software Avenue
Nanjing
Jiangsu, 210012
China
Email: zhou.fenlin@zte.com.cn
Sheng Wang
ZTE Corporation
No.50 Software Avenue
Nanjing
Jiangsu, 210012
China
Email: wang.sheng7@zte.com.cn
Dongyu Yuan
ZTE Corporation
No.50 Software Avenue
Nanjing
Jiangsu, 210012
China
Email: yuan.dongyu@zte.com.cn
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