Operating Manual
KE3600
xDSL
M
ULTI
T
EST
Glossary
ATM
Asynchronous Transfer Mode (ATM) is a data transmission technique where the data traffic, encoded in small
packets termed cells or slots of a fixed length (53 bytes where 48 bytes are data and 5 bytes are the cell
header), is sent via asynchronous time multiplexing. ATM Adaptation Layer (AAL):The task of the AAL is to
adapt data from higher layers to the format of the payload data field of the ATM cell and to transmit control
information to the other side. IP uses the ATM Adaption Layer 5 (AAL5). AAL5 adaptation mainly performs the
segmenting and reassembling of IP packets that do not fit into the short payload data field.
BERT
Bit Error Rate Test: The measurement to determine the bit error rate on transmission paths is known as the
BER test or BERT. It is usually performed using test bit patterns transmitted by a measuring device, received
again following transmission, and then compared.
Bridge
In a computer network, a bridge connects two segments on the level of layer two (link layer) of the OSI model.
A bridge can work on the sublayer MAC or the sublayer LLC. It is then termed a MAC bridge or LLC bridge.
Another difference is the way of determining the route of data packets in a transparent bridge and source
routing bridge. The bridge mode of a DSL modem is usually a transparent mode, i.e., it only provides the data at
the ETH port or takes them and makes them available at the xDSL port.
CRC
The cyclic redundancy check (CRC is usually used) is a method for determining a check value for data to detect
errors during transmission or storage.
CHAP
CHAP (PPP Challenge Handshake Authentication Protocol) is an authentication protocol that is used with
PPP. It is formally specified in RFC 1994. In contrast to PAP, more value is placed on security when transmitting
the passwords.
DTMF
The multiple frequency method is the conventional dialing technique used in analog telephony and is the
method used today primarily in the telephone exchange technique for transmitting the telephone number to the
telephone network or a telephone system. Another term for the multiple frequency method is DTMF (Dual-tone
Multi-frequency).
ES
Errored Second: one second of measurement time during which one or more bit errors are present. Limit: less
than 8% of the measurement time.
FEC
Forward Error Correction (FEC for short; Error Detection and Correction, EDAC for short, is also often used) is
a technique used to reduce the error rate during the storage or transmission of digital data and represents an
error correction method. If forward error correction is used in a transmission system, the sender redundantly
encodes the data to be transmitted so that the receiver can identify and correct transmission errors without
further requests of the sender.
FTP
The File Transfer Protocol (FTP) is a network protocol for transferring files over IP networks, specified in the
RFC 959 of 1985. FTP is located in the application layer (layer 7) of the OSI layer model. It is used to transfer
files from the server to the client (downloading), from the client to the server (uploading) or between two FTP
servers under client control (File Exchange Protocol). In addition, using FTP, directories can be created and
read or directories and files can be renamed or deleted. Separate connections are used for control and data
transfer: An FTP session starts when the client establishes a TCP connection to the Control Port of the server
(the standard port for this is Port 21). Commands are sent to the server using this connection. The server
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