Universal Plug and Play (UPnP) is a set of networking protocols that permits networked devices, such as personal computers, printers, Internet gateways, Wi-Fi access points and mobile devices to seamlessly discover each other's presence on the network and establish functional network services for data sharing, communications, and entertainment. UPnP is intended primarily for residential networks without enterprise-class devices.
The UPnP technology was promoted by the UPnP Forum, a computer industry initiative to enable simple and robust connectivity to stand-alone devices and personal computers from many different vendors. The Forum consisted of over eight hundred vendors involved in everything from consumer electronics to network computing. Since 2016, all UPnP efforts are now managed by the Open Connectivity Foundation (OCF).
UPnP assumes the network runs Internet Protocol (IP) and then leverages HTTP, on top of IP, in order to provide device/service description, actions, data transfer and eventing. Device search requests and advertisements are supported by running HTTP on top of UDP (port 1900) using multicast (known as HTTPMU). Responses to search requests are also sent over UDP, but are instead sent using unicast (known as HTTPU).
Conceptually, UPnP extends plug and play—a technology for dynamically attaching devices directly to a computer—to zero configuration networking for residential and SOHO wireless networks. UPnP devices are "plug and play" in that, when connected to a network, they automatically establish working configurations with other devices.
UPnP is generally regarded as unsuitable for deployment in business settings for reasons of economy, complexity, and consistency: the multicast foundation makes it chatty, consuming too many network resources on networks with a large population of devices; the simplified access controls don't map well to complex environments; and it does not provide a uniform configuration syntax such as the CLI environments of Cisco IOS or JUNOS.