This illustration shows a server, labeled "server," and a desktop computer, labeled "Client," connected by a communications link with two routers between them. In this illustration, the elements are positioned vertically rather than horizontally. From top to bottom, we see: a server connected by a communications link to a router, with the transmission rate given as "Rs." This router is connected to a second router, and the transmission rate between them is given as "..." The second router is connected to the client, and the transmission rate is given as "Rc."

This illustration, which is also oriented vertically rather than horizontally, shows that bottleneck that can occur when multiple clients download files from multiple servers over a shared network. From top to bottom, we see: Three servers, meant to represent a group of ten servers, and labeled "10 Servers." Each server is connected by a communications link to a router, and each router is connected to a second router. Between these routers, the communications links converge and pass through a pipe, which represents the link in the core through which all ten downloads must travel. This pipe is labeled "Bottleneck link of capacity R." The communications links pass through the pipe and connect with their respective routers. These routers are connected to three desktop computers meant to represent the ten clients, and labeled "10 Clients."