Preliminary understanding of SDN switch-Vecloud

According to the southbound protocol supported by SDN switches, SDN switches can be divided into pure SDN switches (only support OpenFlow protocol), hybrid switches (support Open
Flow protocol and traditional network protocol), self-box SDN switches, and bare switches.
　　From the perspective of virtualization, SDN switches are mainly divided into hardware SDN switches and software SDN switches (virtual switches). The software SDN switch does not include white box SDN switches and bare switches.
　　The most influential SDN virtual switch is the OVS (Open vSwitch) switch, which has good working performance and has been widely used in business. OVS is a
multi-layer virtual switch using Apache 2.0 license. Through programmable expansion, OVS can support
large-scale network automation while supporting standard management interfaces and protocols (such as NetFlow, sFlow, IPFIX, RSPAN, CLI, LACP). The self-standard of OVS is to realize an industrial-grade switch that supports standard tube interfaces and opens forwarding functions to realize programmable expansion and control. OVS can well realize the function of virtual switch in the VM environment. In addition to opening standard control and visual interfaces to the virtual network layer, OVS can well support distributed virtual switches across physical servers.
　　SDN hardware switches have poor performance in the early stages of manufacturing, and usually can only achieve half of the functions of software switches. However, with the development of SDN, the scenarios in which SDN hardware switches are used in production environments continue to grow. They are powerful and suitable for extreme work pressure. Large SDN hardware switches have been widely produced.
　　Pure SDN switches are only responsible for the forwarding service of data packets. The SDN switch maintains a flow table, and all flow entries in the flow table are issued by the SDN controller that controls it. When a data packet enters the switch, the switch searches the flow table to confirm whether there is a flow entry match. If there is a flow entry that matches successfully, it executes the operation specified by the flow entry (such as modifying the data packet); if not, it checks whether Discard has been set; if it has been set, the data packet will be discarded; if it is not set, the data packet will be completely forwarded according to the setting or partial information of the data packet will be forwarded to the controller. After the controller sends the flow entry, it will be based on this flow table Item to perform related operations. This is the biggest difference from traditional switches.
VeCloud is headquartered in Hong Kong and has branches in Beijing and Shenzhen, China. It is a technological innovation enterprise that provides cloud exchange network services as its core business to enterprises. Based on innovative cloud network technology, as well as high-quality global network and IDC data center resources, the VeConnect platform, which is directly connected to the world and quickly accessible, is launched to realize the direct connection of network service providers, IDC data centers, cloud service providers, and enterprise application service providers. Connect and communicate to provide enterprises with efficient, safe, stable and reliable network connection services. http://www.vecloud.com/products/ip-transit.html