Multi Service Edge Device HL950
Administrator’s Guide
Page 149 (159)
EN/LZT 108 5995 R3
June
2003
Cell
A
unit of transmission in ATM. A fixed-size frame consisting of a 5-octet header and a 48-octet
payload.
CES – Circuit Emulation Service
CESoATM – CES over ATM
CESoIP – CES over IP
CESoPSN – CES over Packet Switched Network
Checksum
A simple error-detection scheme in which each transmitted message is accompanied by a numerical
value based on the number of set bits in the message. The receiving station then applies the same
formula to the message and checks to make sure the accompanying numerical value is the same. See
also CRC.
CLI – Command Line Interface
CNO – Corporate Network Operator
COE – Central Office Equipment
CPE – Customer Premises Equipment
End user equipment that resides on the customer’s premise which may not be owned by the local
exchange carrier.
CRC – Cyclic Redundancy Check
A common technique for detecting data transmission errors. A number of file transfer protocols use
CRC in addition to checksum. See also Checksum.
CSU – Channel Service Unit
An interface for digital leased lines that performs loopback testing and line conditioning.
CTD – Cell Transfer Delay
This is defined as the elapsed time between a cell exit event at the measurement point 1 (e.g. at the
source UNI) and the corresponding cell entry event at the measurement point 2 (e.g. the destination
UNI) for a particular connection. The cell transfer delay between two measurement points is the sum
of the total inter-ATM node transmission delay and the total ATM node processing delay.
CTS – Clear to Send
D
Data Integrity
Traditionally, data integrity checking has involved attaching a checksum to a string of data to check
against accidental data corruption. More sophisticated security algorithms add other validity checks
such as time and date stamps to make sure data is not intercepted or altered.
Data Privacy
To prevent data from being read by humans or machines during transmission, data privacy algorithms
such as Data Encryption Standard (DES) encrypt and then decrypt the data before and after
transmission.