先决条件 –局域网和广域网
1. 软件定义网络(SDN)：
SDN 的构建是为了支持在局域网 (LAN) 中以及在委托提供商网络中发现的计算机需求。目标是开发动态、灵活、可扩展的连接，以支持 DC(数据中心)和核心网络上不断变化的需求。 SDN 是直接可编程的，提供了一个敏捷的集中管理平台，该平台将控制平面(关于流量路由位置的决策)与信息平面(决定流量如何转发)分离。
2. 软件定义的广域网 (SD-WAN)：
SD-WAN 可能是一种常用的替代解决方案，它允许组织通过利用宽带和 MPLS 将众多分布式位置链接在一起。 SDN 和 SD-WAN 之间的最大区别在于 SD-WAN 专注于提供将多个站点连接在一起的良好区域网络 (WAN)。
区别 ：
SDN 和 SD-WAN 都支持将控制平面与信息平面分离以形成更智能的网络的等效方法。就像同卵双胞胎一样，他们看起来和听起来很相似，但他们彼此完全不同。 SDN 和 SD-WAN 之间的主要区别在于它们的用途。
SDN和SDN-WAN的区别：
| S.NO | SDN | SDN-WAN |
| 1. | Software Defined Networking. | Software-Defined Wide Area Networks. |
| 2. | Operates a LAN or a service provider’s core network. | Enables connections between networks and users across geographies. |
| 3. | Programmable by the user to deliver bandwidth on-demand. | It is programmed to give operational simplification, integrated security and traffic prioritization. |
| 4. | Offers visibility into the real-time analytics and also in the core network performance. | Offers visibility into the real-time analytics and also in the WAN environment. |
| 5. | Provides a centralized view for automation of network services. | Focuses on software-defined application routing capabilities. |
| 6. | Designed by the user. | Configured by the vendor. |
| 7. | Variations of commodity and specialized switching hardware. | Off-the-shelf x86 appliances – physical, virtual, cloud. |
| 8. | Technology has taken a long time to mature. | Recent technology but maturing very rapidly. |
| 9. | Similarities of separating the control and data plane. | Similarities of separating the control and data plane. |