What's Universal Plug and Play?
Universal Plug and Play, or UPnP, is a set of networking protocols that allows different devices in your home network to seamlessly discover each other and communicate and share data. Think of it as a language that your networking devices use to speak to each other, helping to simplify the process of network configuration.
Many popular routers use UPnP, as does the Slingbox -- this greatly simplifies the process of properly configuring the two for Internet Viewing. Some routers use this logo:
Consult your router's documentation if you're uncertain whether it supports the UPnP protocol.