Daisy chain (information technology)

For other uses, see Daisy chain.

Daisy chain is a term used variously in information technology. Its meaning differs according to technology domain, although each preserves the traditional meaning of connecting like items to each other in a series or chain.

Computer software

A daisy chain software installation can continue in piecemeal fashion. This is of particular use with downloaded software. If the connection to the download server is lost during the installation process, daisy chaining allows installation to restart from where it stopped. Google Pack provides this capability.

Computer hardware

Some hardware can be attached to a computing system in a daisy chain configuration by connecting each component to another similar component, rather than directly to the computing system that uses the component. Only the last component in the chain directly connects to the computing system. For example chaining multiple components that each have a UART port to each other. The components must also behave cooperatively. e.g., only one seizes the communications bus at a time. SCSI and Firewire devices can also be daisy chained.

Network topology

Main article: Network topology#Daisy chain

System access

Users can daisy chain computing sessions together. Using services such as telnet or SSH, the user creates a session on a second computer via telnet, and from the second session, telnets to a third and so on. Another typical example is the "terminal session inside a terminal session" using RDP. Reasons to create daisy chains include connecting to a system on a non-routed network via a gateway system, preserving sessions on the initial computer while working on a second computer, to save bandwidth or improve connectivity on an unstable network by first connecting to a better connected machine. A less wholesome purpose is camouflaging activity while engaged in cybercrime.