Configuring DS0 Bundles > Overview

Overview

The NMC-RX application supports DS0 bundles on the following modules: CT3, CT1, and CE1.

DS0 bundles are aggregates of digital signal level 0 (DS0) timeslots that define the bandwidth available to carry data over a fractional T1 (FT1) channel. The bundle can have 1 to 31 DS0 timeslots.

T1 networks transmit data at 1.544 Kbps. The digital signal that supports the T1 carrier is digital signal level 1 (DS1). Each DS1 is an aggregate of 24 or 31 DS0s. DS0 transmits digital signals at 64 Kbps over a single channel on a T1 carrier. See Table 40 for a comparison of the three modules that you can configure with DS0 bundles. The DS0 column indicates the number of DS0 bundle timeslots for each DS1.

 Table 40:  Digital Signals

 Module Type
 DS3
 DS1
 DS0

 CT3

 3

 28

 24


 CT1

 0

 24

 24


 CE1

 0

 20

 31



 

Terminology

Table 41 describes some of the terms used in this discussion of digital signals and T-carriers.

 Table 41:  Terminology  

 Term
 Description

 Bandwidth

 Transmission capacity of the network medium, measured in bits per second (bps); the difference between the highest and lowest frequencies in a given range


 Carrier

 Specified frequency that can be modulated to convey information


 Digital signal

 Signal in which information is represented by discrete states (rather than by a continuous stream as in analog signals)


 Framing type

 Method for distinguishing digital channels that are time-division multiplexed together


 HDLC

 High-Level Data Link Control (HDLC); a bit-oriented synchronous data link-layer protocol, which specifies a data encapsulation method on synchronous serial links using frame characters and checksums.


 Ones density

 Insertion of a binary 1 whenever eight successive zeros (0s) are transmitted to maintain the presence (referred to as density) of 1s in a binary string



 

T-Carriers

T-carriers are digital WAN data transmission facilities. The following sections describe T-carriers, T1 and T3.

T1

T1 transmits digital signal level 1 (DS1) formatted data at 1.544 Mbps through the telephone-switching network, using Alternate Mark Inversion (AMI) or B8ZS coding. The corresponding European (CCITT) carrier is E1, with a data rate of 2.048 Mbps. Fractional T1, a subset of T1, provides T1 benefits at less cost by allowing you to use a fraction of a T1 line's capability. (This fraction is a DS0 bundle.)

Fractional T1

Fractional T1 (FT1) is a subchannel on a T1 line. FT1 is a fraction of the data-carrying capacity on a T1. A T1 line contains 20, 24, or 28 channels, each with a data transfer capacity of 64 Kbps.

FT1 lets you rent any number of DS0 timeslots in each channel. The transmission method and speed of transfer remain the same. Overhead bits and framing are still used, but the channels that are not rented contain no data. DS0 bundling is the method used to define the bandwidth for an FT1 subchannel.

T3

T3 transmits digital signal level 3 (DS3) formatted data at 44.736 Mbps through the telephone-switching network. The corresponding European (CCITT) carrier is E3, with a data rate of 34.368 Mbps. T3 transmits only over a CT3 module.

Digital Signal Levels

Digital signal levels define the data rate (often referred to as speed) of transmitting data over a single channel. The following sections provide information about DS0, DS1, and DS3 levels.

DS0

Digital signal level 0 (DS0) is the basic unit used in transmitting digital signals at 56 Kbps or 64 Kbps over a single channel on a T1 carrier; 64 Kbps is currently the standard rate. However, you may need to use 56 Kbps for older devices.

DS1

Digital signal level 1 (DS1) is a framing specification used in transmitting digital signals at 1.544 Mbps on a T1 carrier (in the United States) or at 2.108 Mbps on an E1 carrier (in Europe).

DS3

Digital signal level 3 (DS3) is a framing specification used in transmitting digital signals at 44.736 Mbps on a T3 carrier (in the United States) or at 34.368 Mbps on an E3 carrier (in Europe).