Network Working Group D. Liu
Internet-Draft China Mobile
Intended status: Informational K. Yap
Expires: April 27, 2015 Google
C. Perkins
Huawei
T. Sun
H. Deng
China Mobile
October 26, 2014
Cloud Based Mobile Core Network Problem Statement
draft-liu-cloud-mobile-core-02
Abstract
This document introduces a IP cloud based mobile core network
architecture. The motivation and the key problems that need to be
further studied by the community are analyzed. The purpose of this
document is to call the community's attention and interest to study
the key technologies and protocols to realize this cloud based mobile
core network.
Status of This Memo
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This Internet-Draft will expire on April 27, 2015.
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Copyright (c) 2014 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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. The motivation for cloud based mobile core network . . . . . 3
4. Cloud based mobile core network architecture overview . . . . 4
5. Problem statement of cloud based mobile core architecture . . 5
5.1. Control and data plane separation . . . . . . . . . . . . 5
5.2. Mobility management . . . . . . . . . . . . . . . . . . . 5
5.3. Network slicing . . . . . . . . . . . . . . . . . . . . . 6
5.4. Network auto-configuration . . . . . . . . . . . . . . . 7
6. Open API . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
12. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The mobile network has been evolved from 2G, 3G and now the 4G
network is being deployed by many operators. Traditionally, the
mobile core network equipment is dedicated telecom equipment, many of
them are based on dedicated hardware platform, e.g. CPCI. The core
network equipment's software is normally tightly coupled with the
hardware. The purpose of this dedicate hardware and software
integrated approach is to achieve telecom level high performance and
high reliability. But the consequence of this design approach is the
lack of flexibility of the network. Current mobile network is facing
the challenge of the booming of the mobile Internet. The mobile
network not only facing the very fast increasing of the data traffic
and also have to face the challenge from OTT applications. Those
challenges require the mobile core network having more flexibilitys.
This document proposes a cloud based mobile network architecture to
meet those challenges.
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2. Conventions used in this document
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 [RFC2119].
3. The motivation for cloud based mobile core network
Current mobile network is facing the following challenge:
1. The fast increasing of the data traffic. According to Cisco's
visual networking prediction,the mobile Internet traffic will
increase 66% CAGR from 2012 to 2017. Such high volume of data
traffic will not only put a lot of pressure to the wireless access
network side but also give a lot of challenge to the mobile core
network side. For example, in current mobility management
architecture, both the Mobile IP protocol developed by IETF and the
GTP protocol developed by 3GPP share a common idea that there will be
one or more IP anchoring points that maintain the home address of the
mobile node and its topological routable IP address. The fast
increasing of the mobile data traffic will give much pressure to the
mobile anchor point. IETF DMM working group was formed to tackle
this problem by distributing of the anchor point. A more radical
approach is that there is no anchoring point in the network, it will
relay on the routing system or SDN to take care of the mobility
management.
2. The lack of flexibility of network functionality. Although the
telecom industry is trying to decouple the service and the network
but we still can see that in current mobile network architecture it
is very difficult to deploy a new service or upgrade the network's
capability. Since currently, most of the mobile core equipment is
build on the CPCI hardware platform and the software normally tightly
coupled with the hardware platform. It is very difficult to change
or upgrade the network equipment's functionality in an agile way. On
the other hand, the mobile operators want to provide more intelligent
and value added service other than to be a just dumb pipe providers.
That will also require the mobile core network has the flexibility.
3. The lack of flexibility of service deployment. When the operator
wants to deploy a new service, it is needed to make the network
upgrade plan carefully and need to do the trial deployment in a small
area to guaranty that the new service and network upgrading will not
affect the production network. The whole process of a new service to
be deployed normally takes several months even years.
4. The challenge of reducing the CAPEX and OPEX cost. The mobile
operators need to lower both the CAPEX and the OPEX of their network,
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especially when they are facing the fast increasing of the data
traffic. Dedicated hardware and tightly coupled software also makes
the CAPEX and OPEX at a high level.
4. Cloud based mobile core network architecture overview
This section discuss the cloud based mobile core network
architecture.
Cloud
...........
(' ')
( )))
((( +-----------+ )))
(( |Mobile Core| )))
((( +-----------+ )))
('..............')
|
| IP Transmit Network
(.........)
( )) MN-Internet communication
( ^ ))
^ > > >( ^ ))> > > > > > > > >
^ (( ^ ) v
^ (.........^.) v
^ +-------| | ^| v
^ | | ^+--------------+ v
^ | | < < | v MN-MN communication
^ | | ^ | v
+--------------+ +--------------+ +--------------+
|Access Network| |Access Network| |Access Network|
+--------------+ +--------------+ +--------------+
^ ^ v
^ ^ v
+---------+ +---------+ +---------+
| MN | | MN | | MN |
+---------+ +---------+ +---------+
Figure 1: Cloud based mobile core network architecture
In this architecture, the mobile core network is located in the
cloud/data center. That could be the operator's private cloud. The
access network is connected to the mobile core network through IP
transmit network. The mobile core network could run in a virtualized
platform in the cloud/datacenter.
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5. Problem statement of cloud based mobile core architecture
5.1. Control and data plane separation
The cloud based mobile core network architecture implies the
separation of the control and data plane. The control plane is
located in the cloud and the data plane should be distributed.
Otherwise, all the data traffic will go through to the cloud which is
obviously not optimized for the mobile node to mobile node
communication.
For the mobile node to Internet communication, the Internet access
point normally is located in the metro IP transmit network. In this
case, the mobile node to Internet traffic should also go through from
the Internet access point instead of go to the mobile core in the
cloud.
However, in some deployment scenario, the operator may choose to put
the mobile core cloud in the convergency layer of IP metro network.
In this case, the Internet access point may co-located with the
mobile core cloud. In this case, the mobile node to Internet traffic
may go through the mobile core cloud.
5.2. Mobility management
Since the control plane and data plane are separated and the data
plane is distributed, traditional mobility management can not meet
this requirement.
Distributed mobility management or SDN based mobility management may
be used in this architecture to meet the traffic routing requirement
(e.g. MN to MN and MN to Internet traffic should not go through from
the mobile core cloud.).
IETF DMM working group is currently specifying distributed mobility
management protocol which maybe suitable for this cloud based mobile
network architecture. The key features of distributed mobility
management are as follows:
Seperation of control plane and data plane of mobility management.
This feature enable the operator to concentrate the mobile core
network's control plane function. Those control plane functions
can be virtulized and running on generic cheaper hardware.
Data plane distribution. This feature allows the data plane
traffic be distributed according to the geographic topology.
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5.3. Network slicing
Network slicing is a technology that can 'slice' a physical network
into different pieces. Each piece is logically independent from each
other. One example of network slicing technology is FlowVisor.
FlowVisor [FlowVisor] is based on open flow protocol, multiple open
flow controller could be connected to the FlowVisor and the FlowVisor
connect to the physical switches. The FlowVisor can translate the
flow control command from the controller above the FlowVisor in to
the flow control command specific to the network slice that allocated
to this controller. For example, in figure 2, from controller A's
perspective, it believes that it has the full control of all the
physical network. Also from controller B's perspective, it also
believe that it has the full control of all the physical network.
Multiple controllers do not interfere from each other.By this way,
multiple controller can share the same physical network and the
physical network is sliced into multiple pieces.
+----------+ +----------+ +----------+
|Controller| |Controller| |Controller|
| A | | B | | C |
+----------+ +----------+ +----------+
| | |
+-----------------------------------------+
| |
| Flow Visor |
| |
+-----------------------------------------+
|
+-----------------------------------------+
| |
| Physical Network |
| |
+-----------------------------------------+
Figure 2: FlowVisor
Network slicing can provide a flexible network capability for the
operator. For example, the operator can deploy a new service in a
new network slice without worry about affecting the production
network's service.
FlowVisor is only one example for network slicing and network
virtualization. Furthermore, how to combine network slicing and
mobility management in the cloud based mobile core architecture is an
important topic need to be further studied.
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5.4. Network auto-configuration
Network auto-configuration is a way to simplify the network operation
and reduce the network OPEX. In an ideal case, the mobile access
network should be registered automatically to the mobile core network
without manual configuration. IETF has defined CAPWAP for wireless
access point control and configuration. However, how to keep the
auto-configuration protocol compatible with existing mobile network
protocols need to be further studied.
6. Open API
The cloud based mobile core network can provide open API to the
service provider and other third party developers. This feature will
faciliate the developers to use the ability of the network.
7. Conclusion
This document discusses the motivation and challenges of the cloud
based mobile core network. There are several key points that need to
be further studied by the community.
1. Innovative mobility management scheme that fulfils with the
distributed data plane traffic routing and network slicing
requirement.
2. Network slicing. FlowVisor is one example of network slicing
technology that based on openflow. Further study should be made
regarding how to virtualize the mobile core network.
3. Network auto-configuration. How to define a mobile network auto-
configuration protocol while keeps the backward compatibility with
current mobile network need to be further studied.
8. Security Considerations
Security should be studied when design the cloud based mobile core
network.
9. IANA Considerations
10. Contributors
11. Acknowledgements
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12. Normative References
[FlowVisor]
"FlowVisor: A Network Virtualization Layer", 2009.
[IEEE-802.11.2012]
March 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[openflow]
"OpenFlow Switch Specification", 2012.
Authors' Addresses
Dapeng Liu
China Mobile
No.32 Xuanwumen West Street
Beijing 100053
China
Email: liudapeng@chinamobile.com
Kok-kiong Yap
Google
Email: yapkke@gmail.com
Charles E. Perkins
Huawei
Email: charliep@computer.org
Tao Sun
China Mobile
No.32 Xuanwumen West Street
Beijing 100053
China
Email: suntao@chinamobile.com
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Hui Deng
China Mobile
No.32 Xuanwumen West Street
Beijing 100053
China
Email: denghui@chinamobile.com
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