You are reading:
Protecting Your Data: A Guide to Windows Firewall

User Datagram Protocol (UDP)

Unlike TCP, UDP packets aren't concerned with a data verification process. When data is sent via UDP from one computer to another, the information is sent and forgotten. An acknowledgment of the UDP data is neither required nor expected. Applications that use voice over IP (VoIP) often use UDP, since voice communication doesn.t allow enough time to recover from a lost or corrupted packet.

Of course, there will be some applications that use UDP but still want to recover when data doesn.t make the trip across the network. In these cases, it's the responsibility of the individual application to handle the data recovery process.

Similarities between TCP and UDP
Although TCP and UDP have many operational differences, they also have a number of similarities. Both TCP and UDP use the IP protocol to traverse the network, and both TCP and UDP use port numbers to separate themselves from other applications on the same computer.

In Windows Firewall, there are advanced configuration options that require the specification of port numbers using either TCP or UDP, but not both. Windows Firewall properly separates TCP and UDP into their own independent categories.