Glossary
O
OSI model | Open System Interconnection model. A reference standard describing the required |
| performance of devices for data communication. Produced by the International |
| Standards Organization. |
P
packet | The unit of data sent across a network. |
PING | Packet Internet Groper. A program used to test whether a destination on a network |
| can be reached. |
port | An access point for data entry or exit within a host using TCP services. |
protocol | Describes message formats and a set of rules used by two or more devices to |
| communicate using those formats. |
PLC | Programmable Logic Controller |
R
repeater | A device that connects two sections of a network and conveys signals between |
| them without making routing decisions or filtering packets. |
router | A device that connects two or more sections of a network and allows information to |
| flow between them. A router examines every packet it receives and decides |
| whether to block the packet from the rest of the network or transmit it. The router |
| will attempt to send the packet through the network by the most efficient path. |
S
server | Provides services to clients. This term may also refer to the computer on which the |
| service is based. |
90 | 840 USE 115 00 Version 1.0 |
