Cisco Certified Technician Latest Update Graded A+

Cisco Certified Technician Latest Update Graded A+ ATM (Asynchronous Transfer Mode) The international standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media, such as E3, SONET, and T3. Bandwidth The difference between the highest and lowest frequencies available for network signals. The term also is used to describe the rated throughput capacity of a given network medium or protocol. The frequency range necessary to convey a signal measured in units of hertz (Hz). For example, voice signals typically require approximately 7 kHz of bandwidth and data traffic typically requires approximately 50 kHz of bandwidth. BRI (basic rate interface) Basic Rate Interface. ISDN interface composed of two B channels and one D channel for circuit-switched communication of voice, video, and data. Broadcast Data packet that are sent to all nodes on a network. Broadcasts are identified by a broadcast address. CD (carrier detect) A signal that indicates whether an interface is active. Also, a signal generated by a modem indicating that a call has been connected. CDP (Cisco discovery protocol) Media- and protocol-independent device-discovery protocol that runs on all Cisco-manufactured equipment, including routers, access servers, bridges, and switches. Using CDP, a device can advertise its existence to other devices and receive information about other devices on the same LAN or on the remote side of aWAN. Runs on all media that support SNAP, including LANs, Frame Relay, and ATM media. Central office (CO) The local telephone company office to which all local loops in a given area connect and in which circuit switching of subscriber lines occurs. Channel Service Unit (CSU) Digital interface device that connects end-user equipment to the local digital telephone loop. Often referred to together with DSU, as CSU/DSU. Checksum Method for checking the integrity of transmitted data. A checksum is an integer value computed from a sequence of octets taken through a series of arithmetic operations. The value is recomputed at the receiving end and is compared for verification. Collision domain In Ethernet, the network area within which frames that have collided are propagated. Repeaters and hubs propagate collisions; LAN switches, bridges, and routers do not. Common Language Equipment Identifier (CLEI) The standard code used by suppliers to identify equipment parts and system configurations. Its a registered trademark of Bellcore (now Telcordia). Customer premises equipment (CPE) Terminating equipment, such as terminals, telephones, and modems, supplied by the telephone company, installed at customer sites, and connected to the telephone company network. Can also refer to any telephone equipment residing on the customer site. Cyclic redundancy check (CRC) Error-checking technique in which the frame recipient calculates a remainder by dividing frame contents by a prime binary divisor and compares the calculated remainder to a value stored in the frame by the sending node. Data Communications equipment (DCE) Devices and connections of a communications network that comprise the network end of the user-to-network interface. It provides a physical connection to the network, forwards traffic, and provides a clocking signal used to synchronize data transmission between DCE and DTE devices. Modems and interface cards are examples. Data Service Unit (DSU) Device used in digital transmission that adapts the physical interface on a DTE device to a transmission facility, such as T1 or E1. The DSU also is responsible for such functions as signal timing. Often referred to together with CSU, as CSU/DSU. Data terminal equipment (DTE) Device at the user end of a user-network interface that serves as a data source, destination, or both. DTE connects to a data network through a DCE device (for example, a modem) and typically uses clocking signals generated by the DCE. DTE includes such devices as computers, protocol translators, and multiplexers. Echo Telephony-Audible and unwanted leak-through of one's own voice into one's own receive (return) path. Hence signal from the transmission path is returning to one's ear through the receive path. Encapsulation Wrapping of data in