Also see SQUID, a UNIX-based program for caching Web pages and other Internet content closer to the user. The abbreviation SQUID also stands for superconducting quantum interference device.
Source Quench Introduced Delay (SQuID) is the use of some algorithms by a computer that is sending messages too fast to a destination computer that will allow
the source computer to slow the timing of its transmissions down to a level acceptable to the destination. On the Internet, when packets arrive at a destination host (computer) faster than the host can handle them, they are discarded and a reply may be sent back indicating that they should be resent. Although a destination host may have a message buffer, the buffer may become full before new packets can be read by a higher-layer application. Having a way to slow down the pace at which packets are sent would not only make work more efficient for both sender and receiver but would reduce unnecessary network traffic. SQuID describes a kind of packet that is returned as a source quench message. The source host would use an algorithm to react to one or a sequence of source quench messages.
SQuID is described in a Request for Comments paper of the Internet Engineering Task Force (IETF).