OpenFlow is not the only way to change the network.

APIs and various message protocols, including some standards, allow users to build today's Software Defined Network (SDN ). However, the key issue is that not all people can achieve the same network, or they can achieve it in the same way. So,OpenFlowCan we lead all of us to the SDN Park in the same way?

OpenFlow is an open-source API that allows you to program the network of switches and routers from multiple vendors by using software running on a centralized control unit to implement a "software-defined network. OpenFlow separates the programming of routers and switches from the underlying hardware, and defines the traffic of routers and switches of multiple manufacturers using software to achieve traffic management and network design consistency.

OpenFlow advocates said that this API and related protocols, as well as SDN, will provide an abstraction layer, or set a virtualization layer between network control and physical infrastructure, it will make the network more open and more innovations can be achieved.

Derek Silva, analyst at Info-Tech research group in London, said, "we have all realized that to manage networks across multiple data centers, and this network is not owned by the enterprise, this management difficulty is very complex, even though we are making progress in all other aspects. "The simpler the network management requirements, the better. I think the future vision proposed by the SDN movement and OpenFlow promoter Open Network Foundation may be the best way to achieve this goal.

But other factors are also playing a role, such as the physical location where the traffic controller should be placed. These factors are allowing us to look at some problems beyond OpenFlow.

Peter Christy, co-founder of the Internet research group, a consulting firm, said, "The discussion about OpenFlow assumes that controllers are placed on a separate device. A reasonable SDN configuration is to distribute the controller software to each switch. In this case, it makes no sense to implement a normal communication protocol within the switch.

Christy believes that distributing the controller software to each vswitch will improve the communication performance between the vswitch and the Controller and improve the SDN operation. In his opinion, Juniper's QFabric architecture is an example of sdn of the distribution controller.

The Arista Network believes that its switch customers can use controllers or distributed network control to implement SDN. Arista said that the two methods have their own advantages and disadvantages, but to implement a comprehensive SDN, both methods are required.

Arista defines four pillars of software-defined cloud networks: cloud topology, distributed control, network virtualization, and management/automation. OpenFlow is only one of multiple methods to implement controller-based SDN management/Automation pillars. Other implementation methods include CLI, SNMP, XMPP, Netconf, OpenStack, and VMware vSphere virtualization software.

Jay Shree Ullal, CEO of Arista, believes that each method has an implementation case. In her opinion, the implementation case of OpenFlow is dynamic grouping redirection, which can be used for Network Routing aggregation, legal listening/electronic monitoring (lawful intercept/CALEA) and segment deployment of topology unknown networks.

It remains to be observed which implementation cases will be widely accepted.

She strongly agrees with the opportunity to fully popularize software-defined networks. However, it is difficult to predict whether OpenFlow will become an API, OpenStack, Netconf, XMPP, VMware, or another hypervisor. Ullal said that all these methods promise topology-Unknown network virtualization and can be optimized for the mobility of applications and workloads.

At this year's VMworld conference, Arista demonstrated how to use simple pre-configuration of virtual machines to build the cloud, and use its EOS operating system software and CloudVision interface to achieve a maximum of 50 thousand network nodes. XMPP is an API in its CloudVision.

"There is no reason to think that there will be no OpenFlow or OpenStack API tomorrow," Ullal said. "But now there is a well-defined interface. We use Netconf and XMPP today because it is easy to implement and has a variety of well-defined specifications, and some of our customers are very interested in this.

Ullal said that Arista's EOS will support a set of APIs that can be used for different "implementation cases" based on user needs. Currently, Arista is investigating the initial market demand of OpenFlow and testing the traffic in the data center to redirect traffic to the shard and shard aggregation devices.

"A New Technology certainly won't exclude other practical methods that can also improve existing technologies," she commented on SDN. "In a widely used legacy operating environment, improving existing technologies is even more important than innovation.

In Ullal's view, not OpenFlow is promoting SDN, but SDN is promoting OpenFlow.

"The combination of OpenFlow and a wider range of sdn apis is crucial for the wider deployment of OpenFlow," she said.

Kyle Forster, co-founder of the Big Switch network, an OpenFlow controller manufacturer, believes that SDN is not so popular in today's market as it can drive OpenFlow. Many APIs must be tailored to adapt to a special "implementation case", which also shows that the market has little need for network programming.

"Among the many programming methods, vendors are trying to make the API very specific. As a result, it is not easy for third-party vendors to write programs on these very specific APIs to make profits, he said. "Many people have realized that, unless there is a standard bottom line, it is almost impossible to create a third-party application ecosystem for OpenFlow.

"OpenFlow is very important, but it cannot be the only choice," said Forrester analyst Andre Kindness. "It is just one of the many choices. It attracts many manufacturers because a large number of communities are developing for them and many talents are working for them. It is initiating numerous discussions and new ways of thinking.