When devices discover each other, to make the devices know more about each other, they exchange information in XML format. When two devices discover each other, they exchange discovery messages, which contain basic information such as the device type and its services.SSDP also allows devices to passively listen to SSDP alive messages from other devices on the network.After the device is added to the network, it can send SSDP alive messages to enable the device to advertise its services to other devices on the network.SSDP (Simple Service Discovery Protocol) is a protocol used by UPnP devices to discover each other. If during the DHCP transaction, the device obtains the domain name through the Domain Name Server (DNS), it uses that domain name, otherwise, it uses the IP.If no DHCP server is found, the device uses a process called AutoIP to assign an IP to itself, which assigns a unique IP to its local network.Therefore, at startup, it acts as a Dynamic Host Configuration Protocol (DHCP) client to assign an IP to itself and searches for a DHCP server. UPnP uses UDP port 1900, and all used TCP ports come from SSDP activity and response messages. HTTPU and HTTPMU were originally submitted as Internet Drafts, but expired in 2001 these specifications have been integrated into the actual UPnP specifications. UDP does not need to confirm the received data and retransmit damaged packets. UPnP uses UDP because of its lower overhead. Related post: How to Find Your IP Address on Windows 10 S/10? (Four Ways) The response to the search request is also sent via UDP, but using unicast (called HTTPU).

By using multicast (called HTTPMU) to run HTTP over UDP (port 1900), device search requests and advertisements can be supported. UPnP assumes that the network runs Internet Protocol (IP), and then uses HTTP on top of IP to offer device/service description, actions, data transfer, and eventing. UPnP devices are “plug and play” because they automatically establish working configurations with other devices when connected to the network. Tip: If you want to know other networking protocols, then you can go to the MiniTool website.Ĭonceptually, UPnP extends plug and play (a technology used to dynamically connect devices directly to computers) to zero-configuration networking for residential and SOHO wireless networks.

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