If you want your ESXi server to be of any use, there's a small matter of making sure you can get network traffic flowing to and from the VMs it hosts. To ensure there isn't a slowdown associated with your configuration, it is essential to learn how to manage a vSphere Standard Switch.
Although the name might imply it's lacking some functionality, the vSphere Standard Switch (vSwitch) has a bevy of features that fit the needs of most IT shops. Christopher Wahl and Steven Pantol go more in depth in Chapter 8 of their book Networking for VMware Administrators. The authors talk about the basics of the vSwitch, such as differentiating the control plane from the data plane, and how to configure security, which has three settings that can be configured.
Wahl and Pantol also talk about how to use the Cisco Discovery Protocol to discover other vSwitches that are in close proximity, and how to control the quantity of traffic that flows through the vSwitch with traffic shaping.
Excerpt from Chapter 8:
Traffic shaping is the ability to control the quantity of traffic that is allowed to flow across a link. That is, rather than letting the traffic go as fast as it possibly can, you can set limits to how much traffic can be sent.
Within a standard vSwitch, you can only enforce traffic shaping on outbound traffic that is being sent out of an object -- such as a VM or VMkernel port -- toward another object. This is referred to by VMware as "ingress traffic" and refers to the fact that data is coming into the vSwitch by way of the virtual ports. Later, we cover how to set "egress traffic" shaping, which is the control of traffic being received by a port group headed toward a VM or VMkernel port, when we start talking about the distributed switch in the next chapter.