Table of Contents



OAM cell

operation, administration, and maintenance cell. ATM Forum specification for cells used to monitor virtual circuits. OAM cells provide a virtual circuit-level loopback in which a router responds to the cells, demonstrating that the circuit is up, and the router is operational.


operations administration maintenance and provisioning.


Ohio Academic Resources Network. Internet service provider that connects a number of U.S. sites, including the Ohio supercomputer center in Columbus, Ohio.

object instance

Network management term referring to an instance of an object type that has been bound to a value.


optical carrier. Series of physical protocols (OC-1, OC-2, OC-3, and so forth), defined for SONET optical signal transmissions. OC signal levels put STS frames onto multimode fiber-optic line at a variety of speeds. The base rate is 51.84 Mbps (OC-1); each signal level thereafter operates at a speed divisible by that number (thus, OC-3 runs at 155.52 Mbps). See also SONET, STS-1, and STS-3c.


originating call control.


Online Computer Library Catalog. Nonprofit membership organization offering computer-based services to libraries, educational organizations, and their users.


8 bits. In networking, the term octet is often used (rather than byte) because some machine architectures employ bytes that are not 8 bits long.


Open Document Architecture. ISO standard that specifies how documents are represented and transmitted electronically. Formerly called Office Document Architecture.


Open DataBase Connectivity. Standard application programming interface for accessing data in both relational and nonrelational database management systems. Using this application programming interface, database applications can access data stored in database management systems on a variety of computers even if each database management system uses a different data storage format and programming interface. ODBC is based on the call level interface specification of the X/Open SQL Access Group and was developed by Digitial Equipment Corporation, Lotus, Microsoft, and Sybase. Contrast with JDBC.


Open Data-Link Interface. Novell specification providing a standardized interface for NICs (network interface cards) that allows multiple protocols to use a single NIC. See also NIC.

OEMI channel

See block multiplexer channel.

Office Document Architecture

See ODA.

Ohio Academic Resources Network

See OARnet.


OSI Internet Management. Group tasked with specifying ways in which OSI network management protocols can be used to manage TCP/IP networks.


online insertion and removal. Feature that permits the addition, replacement, or removal of cards without interrupting the system power, entering console commands, or causing other software or interfaces to shut down. Sometimes called hot swapping or power-on servicing.


other local operator.


Object Management Group.


Open Network Computing. Distributed applications architecture designed by Sun Microsystems, currently controlled by a consortium led by Sun. The NFS protocols are part of ONC. See also NFS.

ones density

Scheme that allows a CSU/DSU to recover the data clock reliably. The CSU/DSU derives the data clock from the data that passes through it. In order to recover the clock, the CSU/DSU hardware must receive at least one 1 bit value for every 8 bits of data that pass through it. Also called pulse density.

online insertion and removal

See OIR.

on-the-fly packet switching

See cut-through packet switching.


1. Out-of-Service.

2. Telecommunications: Out-of-Service signaling.


own point code. Point code of the Cisco SC2200 signaling controller.

open architecture

Architecture with which third-party developers can legally develop products and for which public domain specifications exist.

open circuit

Broken path along a transmission medium. Open circuits will usually prevent network communication.

open database connectivity


Open Data-Link Interface

See ODI.

Open Document Architecture

See ODA.

Open Group

Group formed in February 1996 by the consolidation of the two leading open systems consortia: X/Open Company Ltd (X/Open) and the Open Software Foundation (OSF).

Open Network Computing

See ONC.

Open Shortest Path First


Open System Interconnection

See OSI.

Open System Interconnection reference model

See OSI reference model.

Operation, Administration, and Maintenance cell

See OAM cell.


Operations Provisioning System/lntelligent Network Element. Bellcore OSS that provides provisioning services for intelligent network elements. See also OSS.

Optical Carrier

See OC.

optical fiber

See fiber-optic cable.

Optimized Bandwidth Management

Cisco wide-area switches ensure fair and cost-efficient bandwidth utilization using various techniques. ABR and Optimized Banwidth Management are used for ATM and Frame Relay traffic. ABR is a standards-based ATM traffic management mechanism, and ForeSight is Cisco's implementation that mirrors ABR capabilities for Frame Relay traffic. ABR and Optimized Bandwidth Management optimize real-time traffic performance and throughput, and minimize data loss. Bandwidth management for voice is achieved through the use of standards-based voice compression and silence suppression mechanisms for circuit data services. Formerly called ForeSight.

Organizational Unique Identifier

See OUI.


Open Software Foundation. Group responsible for the Distributed Computing Environment (DCE) and the Distributed Management Environment (DME). See DCE.


Open System Interconnection. International standardization program created by ISO and ITU-T to develop standards for data networking that facilitate multivendor equipment interoperability.

OSI Internet Management

See OIM.

OSI network address

Address, consisting of up to 20 octets, used to locate an OSI Transport entity. The address is formatted into two parts: an Initial Domain Part that is standardized for each of several addressing domains and a Domain Specific Part that is the responsibility of the addressing authority for that domain.

OSI presentation address

Address used to locate an OSI Application entity. It consists of an OSI Network Address and up to three selectors, one each for use by the transport, session, and presentation entities.

OSI reference model

Open System Interconnection reference model. Network architectural model developed by ISO and ITU-T. The model consists of seven layers, each of which specifies particular network functions such as addressing, flow control, error control, encapsulation, and reliable message transfer. The lowest layer (the physical layer) is closest to the media technology. The lower two layers are implemented in hardware and software, while the upper five layers are implemented only in software. The highest layer (the application layer) is closest to the user. The OSI reference model is used universally as a method for teaching and understanding network functionality. Similar in some respects to SNA. See application layer, data-link layer, network layer, physical layer, PQ, session layer, and transport layer.


International association designed to promote OSI in vendor architectures.


Open Shortest Path First. Link-state, hierarchical IGP routing algorithm proposed as a successor to RIP in the Internet community. OSPF features include least-cost routing, multipath routing, and load balancing. OSPF was derived from an early version of the IS-IS protocol. See also IGP, IS-IS, and RIP. See also Enhanced IGRP and IGRP (Interior Gateway Routing Protocol) in the "Cisco Systems Terms and Acronyms" section.


Operations Support System. Network management system supporting a specific management function, such as alarm surveillance and provisioning, in a carrier network. Many OSSs are large centralized systems running on mainframes or minicomputers. Common OSSs used within an RBOC include NMA, OPS/INE, and TIRKS.


Organizational Unique Identifier. 3 octets assigned by the IEEE in a block of 48-bit LAN addresses.


Maximum number of outstanding frames allowed in an SNA PU 2 server at any time.

out-of-band signaling

Transmission using frequencies or channels outside the frequencies or channels normally used for information transfer. Out-of-band signaling is often used for error reporting in situations in which in-band signaling can be affected by whatever problems the network might be experiencing. Contrast with in-band signaling.

Posted: Tue Sep 21 15:22:02 PDT 1999
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