VCenter Server network management

VCenter Server network management is a key part of VMware vSphere 5.1. All virtual machines and physical hosts need to communicate over the network. A real physical network needs to be connected to network devices such as NICs and switches. However, in a virtualized environment, these devices can be achieved through virtualization, which leads to a virtual network. The virtual network runs on the VMware ESXi host, while the ESXi environment runs on the physical machine. At the same time, communication and data transmission between the ESXi host must be supported by the physical network, that is to say, the virtual network is built on the physical network. If you leave the physical network, the virtual network has no meaning. The virtual network runs on a single ESXi physical host. It provides a logical network for the connection between the sending and receiving data of the virtual machines on the ESXi host, then, the data is transmitted to the physical network so that the virtual machine can provide external services. As we all know, in a physical network, a switch can manage network traffic between computers. A switch provides multiple ports, and each port can be connected to a computer or another switch, the administrator can configure the behavior of each port. At this time, the switch will automatically learn the host information connected to the port and use this information to correctly forward network traffic. In a VMware vSphere virtual environment, a virtual network is composed of Virtual Switches. The virtual switch runs in a similar way as a physical switch. However, virtual machines on ESXi are connected to the virtual switch, then, the vswitch checks the information of the virtual machine that is logically connected to its virtual port and uses this information to forward traffic to the correct virtual machine. A vswitch is created by a physical Nic on the host and is connected to the physical network through the physical Nic for external communication and services. VMWare vSphere has two types of Virtual Switches: Standard switches and distributed switches. Standard switch: it is the simplest in the vSphere infrastructure. It runs only inside the ESXi host and connects to the external network through the physical Nic, the connection type of each vswitch determines the network traffic of the vswitch. There are two connection types: Virtual Machine and VMkernel. The virtual machine refers to the vswitch used to process the network traffic of the virtual machine, VMkernel refers to the traffic of the ESXi function services, including vMotion (Real-Time Migration Network), iSCSI and NFS (Storage Access Network), and host management network, when we set these network types and connect them to the uplink adapter (physical Nic), the virtual network is connected to the physical network, in this way, the ESXi host will correctly forward and isolate traffic generated by different operations without affecting each other. Note: Standard switches do not have the advanced functions of physical switches. Distributed switches: they not only have the functions of standard switches, in addition, all associated ESXi hosts in the specified data center act as a single switch, so that the virtual machine can ensure unified network configuration, policies, and statistical information during migration across multiple hosts. This simplifies the management of ESXi hosts in the cluster. Note: If you do not connect to a physical Nic when creating a vswitch, The vswitch is used for internal traffic of the virtual machine, unable to communicate with other hosts on the physical network or virtual machines on other vswitches Port Group: refers to the virtual switch provides a Virtual Machine Access Network Positioning point. Uplink port group (Up-Link): connects a vswitch to the physical Nic of an ESXi host. The maximum number of uplink connections is the maximum number of physical connections established between each ESXi host and the vswitch.