Internet DRAFT - draft-cheng-aponf-ddc-use-cases
draft-cheng-aponf-ddc-use-cases
Network Working Group Y. Cheng
Internet-Draft China Unicom
Intended status: Informational C. Zhou
Expires: January 5, 2015 Huawei Technologies
G. Karagiannis
University of Twente
JF. Tremblay
Viagenie
July 4, 2014
Use Cases for Distributed Data Center Applicatinos in APONF
draft-cheng-aponf-ddc-use-cases-00
Abstract
This document illustrates several distributed datacenter (DDC)
applications and explains how an operator could use APONF to provide
these applications.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Bandwidth Usage Optimization betwen DCs . . . . . . . . . . . 3
4. Server Synchronization between Datacenters . . . . . . . . . 4
5. Low Delay Link Selection between DCs . . . . . . . . . . . . 5
6. On-demand Path Creation between Datacenters . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The APONF (Application-based Policy for Network Functions) work aims
at providing the network management application-based policy
protocol(s), mechanisms and models required by network management
applications to easily, accurately, and efficiently select and use
the available communication network capabilities through the use of
network management policies. A Network Management Application is
used by an a communications service provider and/or operator to
monitor, control, analyze and manage a communication network. An
example of a Network Management Application is a set of actions used
by an Operational Support System (OSS) entity to perform network
configuration. Several APONF use cases have been introduced in the
problem statement document. This document reviews various use cases
for Distributed Data Center (DDC) applications.
Take a large-scale Internet Data Center (IDC) operator as an example,
it provides server hosting, bandwidth, value-added services to
enterprises and ISPs, and has more than 10 data centers using over
one Tbps of bandwidth in a capital city. In this IDC network,
traffic at each site is routed via configuring policy routes and
adjusting routes prioritization to choose an outgoing link. This
type of static provisioning comes with high costs and poor
operability. Furthermore, the link bandwidth resources in the data
centers are not efficiently utilized.
Services usually do not have consistent bandwidth requirements at all
times of the day, e.g. a video service provider usually requires less
bandwidth during business hours and more during evenings. Some
applications have relative high QoS requirements that may change over
time., For example provisioning bandwidth and QoS for all clients of
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an Instant Messaging (IM) app is not reasonable and not a cost-
effective solution. The operator would like to be able to optimize
traffic routes dynamically so as to have the ability to load balance
between data centers and links, and direct customer traffic via
policies (e.g., models, software programs routines) based on customer
grade and QoS requirements.It will also be useful to monitor the
real-time traffic flow and have a visualized report.
Traffic engineering applications can provide dynamic traffic
adjustment demands to the network based on link statuss reported by
the network.
APONF will define network management application-based policy
protocol(s), mechanisms and models required to map application's
demands to network management policies en procedures (e.g. traffic
redirection based on customer's grade and link status), which can be
directly enforced by a network management system on network devices,
to meet the operator's demands.
This document illustrates several distributed datacenter (DDC)
applications and explains how an operator could use APONF to provide
these applications.
2. Terminology
The terminology used in the APONF problem statement draft
[ID.karagiannis-aponf-problem-statement-00] applies also to this
draft.
3. Bandwidth Usage Optimization betwen DCs
A large-scale data center may have more than one hundred links. The
network between data centers is often leased and the applied
bandwidth is very expensive. if the traditional shortest path
algorithm is used to calculate a path based on static cost, then the
path calculation cannot be dynamically adjusted based on real-time
bandwidth usage. This will result in bandwidth waste.
Figure 1 shows how to improve the bandwidth usage efficiency beween
data centers. There are two paths from DC A to DC B, for example,
A-->B (path 1) and A-->C-->B (path 2). When the bandwidth between A
and B is not sufficient, A will automatically transmit the traffic
via C. The network management applications will configure a
threshold T (e.g., 80%) for the path bandwidth usage ratio and send
it to A. When an application request is received, A will detect the
bandwidth usage of both paths. When the bandwidth usage ratio of
path 1 (T1) has exceeded value T (e.g., 90%), while the bandwidth
usage ratio of path 2 (T2) is much less than T (e.g., 10%), it will
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transmit the traffic to B via C, even though P1 is the shortest path
between A and B.
In this case, the available bandwidth between A and B will be used
efficiently, and risks of congestion between the datacenters will be
avoided.
+-------------------+
|Network Management |
| |
|Applications |
+--------+----------+
| +----------+
Policy | | |
(Threshold,T) | -> B |
| / | |
| T1 / +----^-----+
| / |
+---v-----+ / |
| |/ |
| A + | T2
| |\ |
+---------+ \ |
\ |
T2 \ +----+-----+
\ | |
-> C |
| |
+----------+
Figure 1: Bandwidth usage optimization for DC Interconnection
4. Server Synchronization between Datacenters
A Data center involves many systems and the server synchronization is
specifically important for DCs. Once there is error in server
synchronization, the system will not run regularly, which brings
mistakes and failures. However, the server synchronization is not
easy to be realized during the daytime when the Data Center servers
are fully loaded services. Instead, many operators choose to make
the synchronization in the evening at some regular intervals.
Figure 2 shows how server synchronization between datacenters can be
realized. Two servers separately in DC A and DC B are required to
synchronize daily. The Network Management Applications, as defined
in the APONF architecture, are configured with several Policies,
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e.g., syn time (2am to 3am everyday for instance) on when to
synchronize the servers, BW (a required bandwidth to be maintained
between the period), and the path information (which path between the
two DCs costs lower). The Network Management Applications will send
these policy information to both DC A and DC B. In this case, the
two servers synchronize automatically everyday from 2am to 3am, which
will guarantee the normal operation of the servers.
+--------------------+
|Network Management |
| |
|Applications |
| |
+---------+----------+
/ \
/ \
/ \
/ Policy \
/ (Syn Time,BW, \
/ Path) \
| |
+-----v----+ +---v------+
| | | |
| A +--------------+ B |
| | | |
+----------+ +----------+
Figure 2: Server Synchronization between DCs
5. Low Delay Link Selection between DCs
Traditional routing algorithms do not consider real-time link
conditions, some requirements of specific applications cannot be met
timely, e.g., delay is a key requirement for the audio services
(Skype for example). How to select a better link based on the delay
of each link becomes important for the application.
Figure 3 shows an example of link selection between datacenters
according to the delay of each link. A value "d" is configured in
the Network Management Applications for the specific applications,
e.g., less than 100 ms. The value "d" will be sent to the ingress
data center A for the A to detect the delays in both links between A
and B. A will transmit the traffic via the link 1 to B if d1 is less
than d and d2 is larger than d. In this case, the service quality
and QoE user experience will be enhanced.
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+--------------------+
|Network Management |
| |
|Applications |
| |
+--------+-----------+
|
|
| Policy (delay value "d")
|
|
| d2
+----v----+ ------------ +----------+
| |/ \ | |
| A |-----------------> B |
| | d1 | |
+---------+ +----------+
Figure 3: Low Delay Link Selection between Datacenters
6. On-demand Path Creation between Datacenters
Figure 4 illustrates a problem related to bandwidth fragmentation.
From DC A to DC B, two paths (A-->B, A-->C-->B) can be reached. From
A to B, only 2Gbps bandwidth is left and 8Gbps is used, and from A to
B via C, the link capacity is 2Gbps. So there is no bandwidth to
transmit the traffic when there is a 4Gbps requirement from A to B,
which causes that the bandwidth is not effectively used.
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There is no
bandwidth to
+----------+ transmit 4G +----------+
| | traffic | |
| A +------------------+ B |
| |10G link (8G used,| |
+----------+ 2G left) +----------+
\ /
\ /
\2G 2G/
\ /
\ /
+----------+
| |
| C |
| |
+----------+
Figure 4: Bandwidth Fragmentation Problem
Figure 5 provides a method to create on-demand path and bundle the
path capabilities between datacenters. The bandwidth bundle
capability is configured and sent to the DC A by the network
management applications. When the bandwidth is not sufficient to
meet the requirements for a specific application, A could bundle the
bandwidth in the two links. The network capability, e.g., bandwidth
bundle capability, is firstly negotiated between network management
applications and the network element via other methods, which are out
of the scope of this document.
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+--------------------+
|Network Management |
| |
|Applications |
| |
+---------+----------+
|
|Policy (Bundle two paths)
|
|
+-----v----+ +----------+
| | 2G | |
| A +--------------> B |
| | | |
+----------+ +----^-----+
\ /
\ /
\ 2G 2G /
\ /
\ /
+----------+
| |
| C |
| |
+----------+
Figure 5: On-demand Path Creation between DCs
7. Security Considerations
Security is a key aspect of any protocol that allows state
installation and extracting of detailed configuration states. More
investigation remains to fully define the security requirements, such
as authorization and authentication levels.
8. IANA Considerations
Not applicable.
9. Acknowledgements
N/A.
Authors' Addresses
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Ying Cheng
China Unicom
P.R. China
Email: chengying10@chinaunicom.cn
Cathy Zhou
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R. China
Email: cathy.zhou@huawei.com
Georgios Karagiannis
University of Twente
Email: g.karagiannis@utwente.nl
JF Tremblay
Viagenie
Email: jean-francois.tremblay@viagenie.ca
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