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 The term backbone refers to the high-traffic-density connectivity portion of any communications network. In packet-switched networks, a backbone is a primary forward-direction path traced sequentially through two or more major relay or switching stations, consisting mainly of switches and interswitch trunks.
 
  
 The original band of frequencies produced by a transducer, such as a microphone, telegraph key, or other signal-initiating device, prior to initial modulation.

In transmission systems, the baseband signal is usually used to modulate a carrier. Demodulation re-creates the baseband signal. Baseband frequencies are usually characterized by being much lower in frequency than the frequencies that result when the baseband signal is used to modulate a carrier or subcarrier.
 
  
 In telecommunication, a Block Check Character is a character added to a transmission block to facilitate error detection. In longitudinal redundancy checking (LRC) and cyclic redundancy checking (CRC), block check characters are computed for, and added to, each message block transmitted. This block check character is compared with a second block check character computed by the receiver to determine whether the transmission is error free.
 
  
 A bit (abbreviated b) is the most basic information unit used in computing and information theory. A single bit is a zero or a one, or a true or a false, or for that matter any two mutually exclusive states.

Terms for large quantities of bits can be formed using the standard range of prefixes, e.g., kilobit (kbit), megabit (Mbit) and gigabit (Gbit). Note that much confusion exists regarding these units and their abbreviations. Although it is clearer symbology to use "bit" for the bit and "b" for the byte, "b" is often used for bit and "B" for byte.
 
  
 The insertion of noninformation bits into data (it should not be confused with overhead bits).

In data transmission, bit stuffing is used for various purposes, such as for synchronizing bit streams that do not necessarily have the same or rationally related bit rates, or to fill buffers or frames. The location of the stuffing bits is communicated to the receiving end of the data link, where these extra bits are removed to return the bit streams to their original bit rates or form. Bit stuffing may be used to synchronize several channels before multiplexing or to rate-match two single channels to each other.
 
  
 In the processing or transmission of digital data, an error-control procedure that is used to determine whether a block of data is structured according to given rules.
 
  
 An error detection and/or correction code in which the encoded block consists of N symbols, containing K information symbols (K < N ) and N-K redundant check symbols, such that most naturally occurring errors can be detected and/or corrected. A neat example of a block code is the (7,4) Hamming code, which transmits N=7 bits for every K=4 source bits.
 
  
 The designation of one or more bits in a block as parity bits used to force the block into a selected parity, either odd or even. Block parity is used to assist in error detection or correction Code.
 
  
 A functional unit that interconnects two local area networks that use the same logical link control procedure, but may use different medium access control procedures.

In communications networks, it is a device that links or routes signals from one ring or bus to another or from one network to another, may extend the distance span and capacity of a single LAN system, performs no modification to packets or messages. It operates at the data-link layer of the OSI-Reference Model (Layer 2), reads packets, and passes only those with addresses on the same segment of the network as the originating user.
 
  
 To simultaneously send the same message or signal to multiple recipients.

In computer networking, a broadcast address is an IP address that allows information to be sent to all machines on a given subnet rather than a specific machine. The exact notation can vary by operating system, but the standard is laid out in RFC 919. Generally, it is found by taking the logical bit complement of the subnet mask and then logically ORing this with the IP address.
 
  
 In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers. Unlike a point-to-point connection, a bus can logically connect several peripherals over the same set of wires.