Glossary

read-only memory

ROM. An information storage chip with permanent memory. Stored information cannot be changed or deleted except under special circumstances (D). Contrast with random access memory.

redundancy

Performance characteristic of a system or product whose integral components are backed up by identical components to which operations will automatically failover in the event of a component failure. Redundancy is a vital characteristic of virtually all high-availability (24 hours/7 days per week) computer systems and networks.

remote notification

A process by which a system is able to inform remote users and workstations of certain classes of events that occur on the system. E-mail notification and the configuration of simple network management protocol (SNMP) trap recipients are two examples of remote notification programs that can be implemented on director-class switches.

remote user workstation

Workstation, such as a personal computer (PC), using HAFM application and Product Manager application software that can access the HAFM server over a local area network (LAN) connection.

repeater

A device that generates and often amplifies signals to extend transmission distance.

rerouting delay

An option that ensures that frames are delivered in order through the fabric to their destination.

resource allocation time-out value

R_A_TOV. R_A_TOV is a value used to time-out operations that depend on the maximum possible time that a frame could be delayed in a fabric and still be delivered.

RFI

See radio frequency interference.

ROM

See read-only memory. Contrast with random access memory.

router

An attaching device that connects two local area network (LAN) segments, which use similar or different architectures, at the reference model network layer (D). Contrast with bridge.

RS-232

The Electronic Industry Association (EIA)-recommended specification for asynchronous serial interfaces between computers and communications equipment. It specifies both the number of pins and type of connection, but does not specify the electrical signals (D).