CISCO-ADSL-DMT-LINE-MIB
This MIB module serves as an enterprise-specific extension of the ADSL-LINE-MIB. The structure of this MIB module shadows the structure of the ADSL-LINE-MIB, table for table. The tables defined by this MIB module contain managed objects that meet the following criteria: 1) A managed object represents an attribute or characteristic specific to DMT (Digital Multi-Tone) modems. 2) The ADSL-DMT-LINE-MIB does not already contain a managed object representing the same information as a managed object. Observe that entries contained by the tables in this MIB module do not augment the corresponding entries in the ADSL-LINE-MIB, as every modem represented by the ADSL-LINE-MIB is not necessarily a DMT modem. Also observe that entries contained by the tables in this MIB module do not augment the corresponding entries in the ADSL-DMT-LINE-MIB, as this assumes that the ADSL-DMT-LINE-MIB defines tables that correspond to every table defined by the ADSL-LINE-MIB. At this time, this assumption does not hold true. *** DEFINITIONS *** AGGREGATE DATA RATE Data rate transmitted by an ADSL system in any one direction. This includes both net data rates and overhead used by the system, including: - EOC - AOC (ADSL Overhead Control channel) - CRC (Cyclic Redundancy Check) check bytes - fixed indicator bits for OAM (Operatings, Administration, and Maintenance) - synchronization control bytes - capacity for bearer channel synchronization control BEARER CHANNEL A user data stream of a specific data rate that is transported transparently by an ADSL system over one of the simplex channels (i.e., AS0, AS1, AS2, or AS3) or one of the duplex channels (i.e., LS0, LS1, or LS2). BIN DMT line coding divides the frequency spectrum above the voice band of a line (i.e., 0-4 kHz) into 255 sub-carriers, each supporting 4.3125 kHz of bandwidth. A 'bin' refers to a single sub-carrier. DATA SYMBOL RATE The average symbol rate (after allowing for the overhead of the sync symbol) at which symbols carrying data are transmitted; that is, 4000 symbols/second. DOWNSTREAM The flow of data in the direction from the ATU-C to ATU-R. LINE RATE The total data rate supported by a line; that is, (sum of b(i) for all i) * 4 kbps. MARGIN (also referred to as 'SNR margin') The difference between the SNR of the received signal and the SNR required to provide a BER of 10E-7. NET DATA RATE The data rate that is available for user data in any one direction; for the downstream direction this is the sum of the simplex and duplex bearer channel rates. SPLITTER Filters that separate the high frequency signals (ADSL) from the voice band signals; (frequently called POTS splitters even though the voice band signals may comprise more than just POTS). SYMBOL The number of bits the transmitter is capable of multiplexing and modulating over all the bins in a single signalling interval. SYMBOL RATE The rate at which all symbols, including the sync symbol, are transmitted; that is, (69/68) * 4000 symbols/sec; contrasted with the data symbol rate. TOTAL DATA RATE The aggregate data rate (q.v.) plus Reed-Solomon FEC overhead. UPSTREAM The flow of data in the direction from the ATU-R to ATU-C. *** ABBREVIATIONS, ACRONYMS, AND SYMBOLS *** ADSL - Asymmetric Digital Subscriber Line. ATM - Asynchronous Transfer Mode. ATU-C - ADSL Transceiver Unit, Central Office end. ATU-R - ADSL Transceiver Unit, Remote terminal end. b(i) - the number of bits (i.e., constellation size) modulated on bin i. BER - Bit Error Ratio. DMT - Discrete MultiTone. DSL - Digital Subscriber Line. EOC - Embedded Operations Channel. FEC - Forward Error Correction. SNR - Signal-to-Noise Ratio. STM - Synchronous Transfer Mode.