本视频来自ON.Lab工程师Luca的讲解，主要介绍了ONOS应用SDN-IP。

Hi, I'm Luca, from ON.Lab. In this video, I will introduce you to SDN-IP.

大家好，我是ON.Lab的卢卡，接下来我将为大家介绍一款ONOS应用：SDN-IP

SDN-IP is an ONOS application that allows your software-defined network to scale and connect to the rest of the Internet.

您可以利用该应用扩展自己的SDN网络并让您的SDN网络与互联网上其他网络进行通信

SDN is a great new way to think about the networking. But, till today, it was difficult for a software-defined network to communicate with the external world.

SDN重新定义了网络架构，但是直到今天，SDN网络仍很难与外部网络进行通信

In the Internet, autonomous systems use BGP as the standard to communicate together and exchange information between the networks. That's why we decided to integrate it into ONOS through the SDN-IP application.

在互联网上，自治系统使用BGP作为标准协议进行通信和信息交换，为了让SDN网络与互联网上其他网络更好地互通，我们通过SDN-IP把BGP集成到了ONOS

In a typical scenario, the SDN network is composed of different OpenFlow switches controlled by ONOS.

在一个典型SDN网络上，ONOS管理着很多OpenFlow交换机

ONOS runs as a cluster comprised of multiple instances cooperating, providing high performances, HA, and scalability.

ONOS运行在由多个实例组成的集群里，该集群提供高性能、高可用性、可扩展性

The external network connects through their BGP routers on the SDN data plane. Also, the SDN controller, expose different BGP speakers that are directly attached to the data plane, just as the external routers.

外部网络通过BGP路由器连接到SDN数据平面，SDN控制器提供很多BGP speaker，这些BGP speaker也像外部路由器那样连接到数据平面

SDN-IP runs on top of each ONOS instance and is connected to the BGP speakers.

SDN-IP运行在每个ONOS实例上并与BGP speaker相连

Only one instance of SDN-IP is active at a time. Other instances are in standby mode and can take over in case the primary fails.

在同一时间，只有一个SDN-IP实例处于主用状态，其他SDN-IP实例处于备用状态，当主用SDN-IP实例故障时，其中一个备用SDN-IP实例升主

When SDN-IP starts up, it parses the configuration files to discover the details of the peering session and install the ONOS instance to let the external routers and the BGP speakers communicate.

SDN-IP在启动时通过解析配置文件来发现对等体会话的详细信息并激活ONOS实例，实现外部路由器和BGP speaker之间的通信

External routers advertise their routes to the BGP speakers, which propagate them to SDN-IP.

外部路由器向BGP speaker通告自己的路由，收到路由后，BGP speaker把这些路由转发给SDN-IP

SDN-IP transforms the route advertisements into intent requests. ONOS, translate the intents into OpenFlow entries on the switches thus enabling the communication between the networks.

SDN-IP把收到的路由通告转换为意图请求后，ONOS进一步把意图转换为OpenFlow表项，下发给交换机，从而实现SDN网络与外部网络之间的通信

Today, I'm gonna show you a demo of the overall working system. During the demo, you will see hosts of external networks communicating together and the reaction of the system to different failure scenarios, like ONOS instances' failures, BGP speakers' failures, and data plane failures of links and routers.

接下来我将为大家演示整个系统的工作情况，在演示过程中，大家将会看到外部网络的主机如何通过SDN网络进行通信以及系统如何应对不同的故障情形，如ONOS实例故障、BGP speaker故障、以及链路和路由器故障造成的数据平面故障

In this demo, we decided to take advantage of the features provided by Mininet cluster edition to geographically distribute the network elements of the testbed into the cloud.

这里我通过Mininet集群模拟云端分散部署的测试床网元

Both the control and the data plane devices have been placed all around the country. The ONOS GUI, can help us visualize the network just described.

控制平面和数据平面设备遍及全国各地，通过ONOS图形化界面我们可以很直观地看到刚才所说的网络

We have controllers on the top and all the data plane components geographically distributed located on the map. This icon represents an external router, while this one represents a BGP speaker.

控制器位于顶部，数据平面组件在地理空间上呈分散式分布，这个图标代表一个外部路由器，而这个代表一个BGP speaker

When SDN-IP is activated, the necessary intents are installed. The BGP sessions are established and the routing information is exchanged.

当SDN-IP激活时，所需意图自动安装，BGP会话自动建立，路由信息自动发送

As you can see, different hosts of the external networks located in Oregon and Virginia are immediately able to communicate together through the SDN network.

正如大家所看到的这样，位于俄勒冈州和弗吉尼亚州的外部网络主机可以立即通过SDN网络进行通信

But, what happens if we start to kill different components? Let's let the ping command continue.

如果我们把不同的组件停掉会发生什么情况呢？让我们继续运行这个ping命令

When we kill the first ONOS instance, as you see, the communication between the hosts is still active. Of course, we can observe the same behavior when a BGP speaker is killed.

第一个ONOS实例停掉之后，主机之间的通信仍然正常保持；当一个BGP speaker停掉之后，主机之间的通信还是正常保持

Through its BGP support, SDN-IP can also recover after data plane failures.

利用BGP，SDN-IP还可以从数据平面故障中快速恢复

Let's simulate a cut on one of the two links connecting the external network in Oregon to our AS. And let's also shut down one of the two routers connecting the external network in Virginia.

现在我们中断俄勒冈州外部网络与我们自治系统之间的两条链路之一，同时我们再来停掉弗吉尼亚州外部网络上的两台路由器之一

As shown in the graphic, thanks to ONOS and SDN-IP, the traffic keeps flowing between the hosts through the SDN network.

如图所示，由于ONOS和SDN-IP所提供的故障保护机制，外部主机之间仍然可以通过SDN网络正常通信

In this video, we demonstrated SDN-IP peering for a transit network as well as the seamless recovery of the application from control and data plane failures.

通过这个演示我们可以了解到SDN-IP在网络转接过程中发挥的对等互联作用及当控制层或数据层发生故障时SDN-IP的快速恢复功能

SDN-IP can transform your software-defined network into a transit network, enabling communication between hosts of different administrative domains.

SDN-IP可以把SDN网络变成一个转接网络，实现不同管理域主机之间的通信

ONOS and SDN-IP enable communication between software-defined network and the rest of the Internet. They make it easier to incrementally migrate from an existing network to SDN. And they can help you to scale your SDN control plane.

ONOS和SDN-IP使得SDN网络可以与因特网上的其他网络进行通信，降低了现有网络向SDN网络进行增量迁移的难度，同时还可以帮我们扩展SDN控制平面。

SDN-IP and ONOS are open source projects, so you are encouraged and welcome to contribute to them at any time.

SDN-IP和ONOS都是开源项目，欢迎大家参与到项目中来

Check out their features and more on the ONOS website.

欲了解更多特性和其他信息，请访问ONOS网站

下面给大家带来完整视频内容，希望你能和SDNLAB双语君在技术学习的过程中一起提升英语能力。

https://v.qq.com/x/page/q03317cnok0.html