You can set up virtual serial port connections for vSphere virtual machines in several ways. The connection method that you select depends on the task that you need to accomplish.
You can set up virtual serial ports to send data in the following ways.
Physical serial port on the host
Sets the virtual machine to use a physical serial port on the host computer. This method lets you use an external modem or a hand-held device in a virtual machine.
Output to file
Sends output from the virtual serial port to a file on the host computer. This method lets you capture the data that a program running in the virtual machine sends to the virtual serial port.
Connect to a named pipe
Sets a direct connection between two virtual machines or a connection between a virtual machine and an application on the host computer. With this method, two virtual machines or a virtual machine and a process on the host can communicate as if they were physical machines connected by a serial cable. For example, use this option for remote debugging of a virtual machine.
Connect over the network
Enables a serial connection to and from a virtual machine's serial port over the network. The Virtual Serial Port Concentrator (vSPC) aggregates traffic from multiple serial ports onto one management console. vSPC behavior is similar to physical serial port concentrators. Using a vSPC also allows network connections to a virtual machine's serial ports to migrate seamlessly when you use vMotion to migrate the virtual machine. For requirements and steps to configure the Avocent ACS v6000 virtual serial port concentrator, see http://kb.vmware.com/kb/1022303.
Server and Client Connections for Named Pipe and Network Serial Ports
You can select a client or server connection for serial ports. Your selection determines whether the system waits for a connection or initiates it. Typically, to control a virtual machine over a serial port, you select a server connection. This selection lets you control the connections, which is useful if you connect to the virtual machine only occasionally. To use a serial port for logging, select a client connection. This selection lets the virtual machine connect to the logging server when the virtual machine starts and to disconnect when it stops.
Supported Serial Ports
When you use a physical serial port for serial port passthrough from an ESXi host to a virtual machine, serial ports that are integrated into the motherboard are supported. A virtual machine can use up to 32 serial ports.
Unsupported Serial Ports
When you use a physical serial port for serial port passthrough from an ESXi host to a virtual machine, the serial ports connected through USB are not supported for serial port passthrough. They might be supported by USB passthrough from an ESXi host to a virtual machine. See USB Configuration from an ESXi Host to a Virtual Machine.
In addition, you cannot use Migration with VMotion when you use a physical serial port for serial passthrough.