O

OC Optical Carrier The optical specification over SONET. An OC level is the optical equivalent of an STS signal. Transmission rates are based on 51.84 Mbps (OC-1). A c following a OC level identifies concatenation of payload (i.e., OC-3c).

ODI (Open Data-link Interface) Novell specification providing standardized access to networks.

OHR Overnight Hardware Replacement (3Com)

OSI (Open Systems Interconnection) The goal for internetworking computers from different vendors, to be achieved by full adherence to international standards. See OSI Reference Model.

OSI Reference Model Seven-layer network architecture model of data communication protocols developed by ISO and CCITT. Each layer specifies particular network functions such as addressing, flow control, error control, encapsulation and reliable message transfer.

OSF Open Software Foundation

OSPF (Open Shortest Path First) Routing protocol for TCP/IP networks.

Output packet filtering Filtering applied to packets after they have been through the router's internal forward processing.