SSDP - the Simple Service Discovery Protocol is used for advertisement and discovery of network services and presence information. It is often enabled in customer end devices (CPEs) such as modems, WLAN modems.
Impact of running open SSDP devices
Since SSDP runs over UDP, again, it can be used for UDP reflection attacks. Details SSDP's amplification factor is ~ 30. It is less powerful than NTP.