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SDN and Dual Control Planes on One Switch
INTERNAL
SDN and Dual Control Planes on One Switch
— What Advantages Does an Agile Network Bring? (Issue 5)
By Swift Liu, President
Enterprise Networking Product Line
Huawei Enterprise Business Group
Agile means quick and nimble.
New services such as mobility, cloud computing, social media, Big Data, and the Internet of Things (IoT) bring
higher requirements for real-time service transmission, network mobility and scalability, as well as improved user
experience. Huawei Agile Network Solution focuses on ways to cope with the challenges brought by these new
services and quickly solve problems they create for traditional networks.
This article discusses Software-Defined Networking (SDN) and the dual-plane solution for easy SDN migration.
SDN
SDN is a hot topic. Originally, it was used only in data centers. Virtual Machines (VMs) migrate when services on
data center networks change; therefore, you need to be able to adjust the network structure. Before the emergence
of SDN, it was difficult to do that. After SDN was developed, the network was considered a resource that could
support a variety of services. When VMs migrate or the IT (computing) layer changes, the network topology
changes correspondingly. In this article, a network refers to a physical network and a virtual network refers to a
network of virtual switches.
When talking about SDN today, most people think about data centers. Despite divergent views of SDN, this article
discusses what problems can be solved by SDN but not what SDN is.
SDN Brings About Network Architecture Innovation
Initially, SDN was used in data centers because VM migration frequently occurred on data center networks.
However, SDN's architectural innovation is also required on campus networks because wireless users and STAs
frequently move from one place to another. Based on this thinking, we introduced the Campus Controller to
campus networks. This is the first time we used the SDN architecture on campus networks.
2013-12-16
Huawei confidential. No spreading without permission.
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SDN and Dual Control Planes on One Switch
INTERNAL
SDN Is Supported in the Hardware Platform
There are many SDN schools and OpenFlow is one of them. In the past two years, four OpenFlow versions,
OpenFlow 1.0, 1.1, 1.2, and 1.3 have been released. Whenever a new version is released, the earlier ones cannot
be used on devices. When OpenFlow 1.3 was released, some people claimed that the earlier versions were still
supported. However, only partial functions are supported.
Previously, we designed special tables for network devices to facilitate packet forwarding. The tables include the
Forward Information Base (FIB) table for route forwarding and the MAC address table for Layer 2 forwarding.
These tables are independent from each other and searched in a predefined order. Each table is designed for a
specific use, but they are not big enough for OpenFlow. OpenFlow defines forwarding control interfaces,
forwarding models, and actions based on services, and adds traffic flows to a flow table. The flow table defines
the actions needed to process each traffic flow. If you want to classify all the traffic flows based on service type,
the flow table must be big. However, a switch supports only hundreds of thousands of FIB entries and 20,000
MAC address entries. FIB and MAC address tables are not large enough when you apply OpenFlow to service
networks.
In practical use, OpenFlow requires a large table size. Since a switch built with an Application-specific Integrated
Circuit (ASIC) architecture cannot provide a large-sized table, we install Huawei's Enterprise Network Processor
(ENP) chip on our switches to solve the problem. The table is now large enough to cover entries demanded by
traditional services and the flow entries of OpenFlow.
Dual Control Planes Support Easy Migration to SDN
At present, many enterprise users want to use SDN technology, but they do not want to change their entire
network to SDN because they must ensure normal service operation on a live network. How can users employ
SDN technology to meet new service requirements and ensure normal service operation at the same time? If this
can be achieved, they can easily migrate their network to an SDN network. Huawei uses one physical network to
provide two logical networks: original protocols and services run on one logical network and SDN runs on the
other to provide new services. An ENP switch supports all the network protocols and SDN. ENP switches with
dual control planes help smooth migration to the SDN network.
SDN Is Supported on the WAN
SDN can be used on Wide Area Networks (WANs). Google was the first to apply SDN technology to the WAN.
Generally, the utilization of enterprise WAN dedicated lines is lower than 40 percent. After using SDN technology,
Google improved its bandwidth utilization to higher than 90 percent.
2013-12-16
Huawei confidential. No spreading without permission.
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SDN and Dual Control Planes on One Switch
INTERNAL
Huawei worked with a customer in China to deploy SDN in the dedicated interconnection line of the customer's
data center. The customer spent several billions on the dedicated line each year, but its usage efficiency was only
about 30 percent. The customer considered that 60 percent of the investment was wasted and wanted to improve
its bandwidth utilization. We used the WAN Controller to improve WAN link utilization to more than 90 percent,
and reduced the customer's WAN link leasing costs.
SDN Provides Openness for Partners and Customers
The SDN network enables a high-level of openness during innovation and design.
The Campus Controller provided for mobile service is highly open and permits redefinition by customers and
partners. Using the Campus Controller, they can define rights- and domain-based policies and QoS policies for
industrial services such as medical, education, and energy.
Security collaboration opens policy definition for Big Data analysis. Customers and partners can define the
policies and content to be analyzed in their own industries for secondary development, and promote and use the
policies they have defined.
It is difficult to design the configuration model of five-level QoS scheduling provided by NE routers. SDN
switches and the SDN network provide open interfaces to enable customers and partners to design the
configuration model by themselves.
The SDN network provides forwarding-level, device-level, NMS-level, and Controller-based Application
Programming Interfaces (APIs), plus APIs for service orchestration that provides a platform for secondary
development.
Summary
SDN will be a useful technology well into the future. So long as it is used in an appropriate way, users will
experience excellent service.
2013-12-16
Huawei confidential. No spreading without permission.
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