O

Object
An object is an external program, in ASP, that can manipulated with an ASP script. When an object is created within an ASP script, it is called an "instance." The process of creating an object is referred to as "instantiation.

OC
The SONET standard defines a signal hierarchy similar to that which you saw for the T-Carriers, but extending to much higher bandwidths. The basic building block is the STS-1 51.84Mbps signal, chosen to accommodate a DS3 signal. The hierarchy is defined up to STS-48, that is, 48 STS-1 channels for a total of 2,488.32Mbps-capable of carrying 32,256 voice circuits. The STS designation refers to the interface for electrical signals. The optical signal standards are correspondingly designated OC-1 (Optical Carrier-1), OC-2, etc.

Octal
The octal numbering system is a positional numbering system just like the decimal system. In the decimal system (base 10), each position starting from right to left is 10 times greater than the position to the right. 10 is 10 times greater than 1, 100 is 10 times greater than 10, 1000 is ten times greater than 100 and so forth. The octal numbering system is base 8. In the octal numbering system the positional value is 8. Each time you move one position to the left the value of that position is 8 times the value to the right. For example 0010 is eight the value of 0001 (8 vs. 1). 0100 is 8 times 0010 (64 vs 8) and so forth.

Octet
An octet is another word for an 8-bit byte. It is an 8-bit binary pattern used to represent a single character. Multiple octets or bytes can be combined to form larger values.

Off-Line
Off-line is a term used to describe a condition when a device is operational but is not actively connected to a network or communications line (online). Personal printers or network printers are often put into an off-line state when paper is being added or when a form feed is being performed. In this condition a computer cannot communicate with the device.

Open Data-Link Interface
The Open DataLink Interface (ODI) is a standard device driver from Novell that provides an interface between network hardware and the higher layer protocols. It supports multiple protocols and device drivers allowing interconnectivity between various types of devices using different architectures and protocols.

Open Profiling Standard (OPS)
OPS is a browser privacy standard that is part of P3P. Under OPS, the user manually determines the type and amount of personal data that is shared from the browser to a Web server.

Open Shortest Path First (OSPF)
OSPF (Open Shortest Path First) is a link-state routing protocol that is becoming increasingly popular as the routing protocol of choice for IGPs. OSPF offers some attractive options such as type of service routing. This allows network managers to define multiple routes to destinations in terms of service type, such as high throughput or minimal delay. This provides an effective method of costing routes. OSPF also allows load balancing across multiple routes. The OSPF protocol requires all exchanges between routers be authenticated. This authentication guarantees that only trusted routers propagate routing information.

Open Systems Interconnection
OSI began as a reference model, that is, an abstract model for data communications, but now the model has been implemented and is in use in some data communications applications. The OSI model, consisting of seven layers, falls logically into two parts-layers one through four, the "lower" layers, are concerned with the communication of raw data, and layers five through seven, the "higher" layers, are concerned with the networking of applications.

Optical Fiber
Fiber optic cable consists of a light-transmitting core surrounded by a reflective cladding layer. Information is transmitted by focusing a light source into the core and then switching it on and off. Light is reflected off of the cladding layer, so nearly all of the light radiated into one end of the cable reaches the other end. Fiber optic cable is not susceptible to loss of signal strength over distance, like copper cable. And, since light is not appreciably affected by electromagnetic fields, a signal in a fiber optic cable is not affected by interference. But, by its very nature, a fiber optic cable must be cut in order to get the received light beam to a detector, as only point-to-point channels are possible; a bus cannot be constructed.

There are two common types of fiber optic transmission techniques, multimode and singlemode. Multimode uses LED (light emitting diodes) to transmit the light and is limited to 3km. Singlemode uses laser and is capable of transmitting distances of 20km and higher.

OSF
OSF stands for Open Software Foundation, a membership organization located in Cambridge, Massachusetts that produces specifications such as the Distributed Communications Environment (DCE).

Out-of-Band Management
This is a network management feature that allows a network device to be accessed "outside" the network, through a terminal directly attached to the device, or through a modem connected to an RS-232 or console port.

Overhead
In data communications overhead refers to the amount of data needed in addition to the application data, to transmit information from one computer to another. In the example of the OSI model, this would be the header of each layer and the trailer of the Data Link Layer. The efficiency of communication devices is determined by the amount of overhead necessary to transmit user information. Efficiency typically decreases as the amount of overhead increases.