【双语频道】6分钟了解ONOS

本视频来自ONOS首席架构师Thomas Vachuska的讲解，视频在短短6分钟左右的时间内深入浅出的对ONOS的架构进行了阐述和分析，并对其功能进行了演示。该视频对于ONOS用户宏观的掌握ONOS很有帮助。下面我们就来快速看看里面的重要细节。

自我介绍开门见山，演讲者字正腔圆，穿的衣服都那么有品位，国外的程序猿升级成架构师之后都这么帅吗？

ONOS说文解字，言简意赅，三句话概括了ONOS的优秀特性

ONOS is a network operating system that was specially built for service providers. ONOS是一款专门为服务提供商打造的网络操作系统

It has been architected to support scalability, high availability and performance. 其架构具备可扩展性、高可用性和高性能

It presents innovative abstractions and these northbound and southbound interfaces. ONOS开创性地引入了一个抽象层，并提供北向和南向接口

It is also modular to allow for ease of support and customization. ONOS还采用模块化结构来轻松实现功能扩展与定制

好了，开始介绍架构了

ONOS is a distributed system and runs as a cluster. ONOS是一个分布式系统，作为一个集群运行

The distributed core manages the state across instances, and is the key component enabling scaling and high availability. ONOS的分布式核心管理所有实例的状态，是实现可扩展性和高可用性的关键组件

A pluggable southbound allows OpenFlow or other protocols to interact with network elements; northbound abstractions and APIs ease application programming. ONOS提供了一个可插拔南向接口来实现OpenFlow或其他协议与网元之间的交互；还提供了北向抽象层和API来简化应用编程

ONOS abstractions include a global network view, allowing applications to program their view of the network, and an application intent framework allowing them to specify what service they want from the network. ONOS抽象层包含一个全局网络视图，允许应用程序对各自的网络视图进行编程；还包含一个应用意图框架，可让应用程序指定其想要从网络上获得的服务

Applications specify what they want and do not have to worry about all of the details of how to achieve it.应用程序只需要指定其需要的服务，而不必考虑诸如怎样实现此服务的细节问题

Their intents are compiled into actionable objectives which are installed into the network. 应用程序的意图会编译成可实施目标，并部署到网络上

For example, an end-to-end connectivity intent compiles into two path intents. 例如，一个端到端的连接意图会编译成两个路径意图

The resources used by the objectives are then monitored and maintained on behalf of the application. ONOS会替应用程序监控和维护用于实现上文所述目标的资源

Links may go down, but ONOS will automatically reroute without application intervention. 如果链路Down掉，ONOS会自动重路由，无需应用干预

开始介绍图形化界面，整体风格还是区域扁平化的，时尚时尚最时尚。

Today, I'm going to show you the user interface to ONOS, and some of its features for scaling and high availability. 今天，我将向大家展示ONOS的用户界面，以及它的一些可扩展性和高可用性功能

On the center of the user interface, you see the network that ONOS has discovered. It is laid out according to GPS information. 在用户界面的中心，可以看到ONOS发现的网络，该网络根据GPS信息排布

The view area can be adjusted by using pan and zoom gestures. 视图区域可以平移和缩放

If I want to move an element, I can easily unpin it and repin it. 想移动网元时，可以轻松地解锁并重新锁定网元

These icons represent switches, and these lines are the links connecting them. 这些图标表示交换机，这些线是连接交换机的链路

These switches have labels, and they can be cycled to present the most useful information about them or no information at all. 这些交换机有标签，可循环显示最有用的信息，也可隐藏所有信息

Icons that represent endstation hosts can be toggled on or off. By default, they are suppressed 表示终端站主机的图标可以显示或隐藏，默认是隐藏的。

In the upper left of the view, we see ONOS instances. 在该视图的左上角，可以看到ONOS实例。

It is easy to see which instance controls which switch by looking at the color. 可以简单地根据颜色来区分各实例分别控制的交换机

For example, these blue switches are controlled by this blue instance. 比如，这些蓝色交换机由蓝色实例控制

In the upper right of the view pane, we see some high level summary information, including the number of intents and flows that are active. 在视图框的右上角，可以看到一些基本的摘要信息，包括意图数量、有效数据流数量等

Presently, there are over 2000 flow rules. You can also see the number of flows active on a link by looking at the number next to the link. These flows will proactively provisioned. 当前，有2000多个流表。链路旁边的数字表示此链路的当前有效数据流数量。这些数据流将被主动发放

Let me add another flow. It is easy to do, simply multi-select two endstation hosts, and press the appropriate action in the multi-select pane. 现在我们添加一个新数据流。操作很简单，只需要选中两个终端站主机，然后在多选框中点击相应操作

ONOS supports both proactive and reactive flows. ONOS支持主动和被动数据流

If you want to see more information about an element on the screen, you can click on it, and this flyout appears. This applies for any network element. 如果想要查看屏幕上某个网元的详细信息，可以点击该网元，旁边会弹出其详细信息页面。该操作适用所有网元

对OpenFlow协议的支持

You will know that this switch is an OpenFlow 1.3 switch, while this one it supports 1.0. ONOS can work with either version of OpenFlow. 可以看到这是一个OpenFlow 1.3交换机，而这个支持OpenFlow 1.0。ONOS兼容上述两个版本的OpenFlow

Also note that by selecting a switch I can see how many flows are egressing each link on that device. 还要注意一点，选择一个交换机后，我们还可以看到从该交换机输出的每条链路上的数据流数量

灵活的选择流量监控方式

We can also choose to monitor all traffic traversing the network. 另外，我们可以选择监控网络上的所有流量

If you want to view only the optical plane, we can select here. To go back to both IP and optical, we select here. 如果只想查看光层拓扑，可以选这里。要回到同时显示IP和光的视图，选这里

Alternatively, for a better perspective on the packet and optical connectivity, we can select the oblique view. 或者，要从更好的角度查看数据包和光路连通性，我们可以选择斜视图

Now, let's take down at link. 现在，我们去掉一条链路

You can see that the flows were automatically rerouted. 可以看到数据流自动重路由

When we set up flows, we are using the intent framework. This northbound interface allows applications to ask for something from the network, without specifying all of the details of how to get it. You can see the active intents for any selected network element. 建立数据流时，我们使用意图框架。此北向接口可让应用程序向网络发起请求，而不用说明获得这些请求内容的全部细节。大家可以看到任意所选网元的工作意图

Now, let's add one more ONOS instance and rebalance the existing switches. 现在我们再添加一个ONOS实例，并重新均衡当前交换机分布

In this manner, ONOS easily scales as you add more switches to your network. 按照这种方式，当大家向网络中添加更多交换机时，ONOS可以轻易实现扩容

Now, let's kill the current ONOS instance. 现在，我们删除一个当前ONOS实例

You can see that all the switches have changed to an alternate ONOS instance and no flows were disrupted. 可以看到该实例下的所有交换机都换到了另一个ONOS实例下，没有数据流中断

Also, the user interface has seamlessly switched over to another instance. 同样，用户界面也可以无缝切换到另一个实例

多么有亲和力的结束语，好帅呢（嘻嘻嘻）。

下面给大家带来完整视频内容，另外我们会附上全文双语版，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。