CSU/DSU

An ISDN service type that provides two B, or data, channels and one D, or management, channel. Each B channel offers 64 Kbps, and the D channel offers 16 Kbps. Supports a total signaling rate of 144 kbps, which is divided into two B or bearer channels running at 64 kbps, and a D or data channel runing at 16 kbps. The bearer channels carry the actual voice, video, or data information, and the D channel is used for signaling.
[view]

A channel that conveys information by altering the performance of a system component or modifying a resource’s timing in a predictable manner. A covert channel in which one process signals information to another by modulating its own use of system resources in such a way that this manipulation affects the real response time observed by the second process. Covert channel in which one process signals information to another process by modulating its own use of system resources (e. g. , central processing unit time) in such a way that this manipulation affects the real response time observed by the second process.
[view]

A channel of communication within a computer system, or network, that is not designed or intended to transfer information. The means by which data can be communicated outside of normal, expected, or detectable methods. Unintended and/or unauthorized communications path that can be used to transfer information in a manner that violates an information system security policy. (. See overt channel and exploitable channel. )
[view]

A channel that conveys information by writing data to a common storage area where another process can read it. A covert channel that involves the direct or indirect writing of a storage location by one process and the direct or indirect reading of the storage location by another process. Covert storage channels typically involve a finite resource that is shared by two subjects at different security levels. Covert channel involving the direct or indirect writing to a storage location by one process and the direct or indirect reading of the storage location by another process. Covert storage channels typically involve a finite resource (e. g. , sectors on a disk) that is shared by two subjects at different security levels.
[view]

There are two forms of ISDN: PRI and BRI. BRI interface supports a total signaling rate of 144 kbps, which is divided up into two B or bearer channels, which run at 64 kbps, and a D or data channel, which runs at 16 kbps. The bearer channels carry the actual voice, video, or data information, and the D channel is used for signaling. PRI or primary rate interface provides the same throughput as a T1 1. 544 Mbps, has 23 B or bearer channels, which run at 64 kbps, and a D or data channel, which runs at 16 kbps.
[view]