Enterasys Networks CSX7000, CSX5500, CSX6000 manual Line Encoding

CONFIGURING RESOURCES AND LINES

Lines

LINE ENCODING

For Primary Rate lines only. Line encoding specifies the nature of the signals that are used to represent binary one and zero at the physical layer. Two encoding methods are Alternate Mark Inversion (AMI) and Bipolar 8 Zero Substitution (B8ZS). AMI as the encoding scheme implies that the applications using the transmission line must guarantee a certain number of 1s in the signal to help prevent a loss of synchronization in the network. This is possible if the voltage level of the signal remains zero for too long a period of time (i.e., too many logical 0s in the transmitted data). B8ZS enforces no such limits on the application using the transmission medium since it introduces bipolar violations in the signal. These violations are in turn interpreted at the receiving end not as errors, but simply as the substitution of a 1 for a 0 after certain number of consecutive 0s were detected in the transmitted signal.

T1 SIGNALING METHOD

For primary rate lines only. The signaling method dictates how and where the call signaling is to be carried. The methods currently available are: Common Channel and Robbed Bit Signaling.

COMMON CHANNEL

In the Common Channel signaling case, one of the 24 channels of the PRI frame is devoted to call control messaging.

ROBBED BIT SIGNALING

In the Robbed Bit Signaling method, 1 bit of each data channel is “robbed” in order to carry the requisite signaling information. This method is only available for Digital Modem resources.

Notes: Mixing RBS lines and Common Channel lines in a single CyberSWITCH will cause some problems with outbound calls. A 64 Kbps data call may try to go out on the RBS line. The WAN card controlling that line will reject the call, as will every other WAN card until a card using a Common Channel line is tried.

The E1/R2 signaling method is specified under Line Characteristics, Framing Type.

LINE BUILD OUT

For primary rate lines only. No matter what the quality of the cabling employed in a network, each and every line experiences some signal loss or degradation. Line Build Out describes the degree of attenuation to be applied to the transmission signal in order to have the correct signal levels and shape arrive at the receiver. Generally, the longer the line connecting the CPE and the network equipment, the less the transmitted signal is attenuated.

CFGEDIT will use short or long haul information to determine the correct Line Build Out (i.e., degree of attenuation) for your lines. The value you input (in CFGEDIT) to determine attenuation depends on whether or not you are using an external Channel Service Unit (CSU).

If you are using an external CSU, you will specify a value under Short Haul Build Out. Specify the length of the line, in meters, from CPE to the CSU by selecting a range from zero to 210 meters.

If you are not using an external CSU, specify a value under Long Haul Build Out. On long hauls, your telephone company will provide you with a decibel attenuation value when they install the lines. The installers may specify option labels A, B, or C during installation. If so, these labels correspond, respectively, to Long Haul Build Out values of -0.0dB, -7.5dB, and -15.0dB. The value is dependent on distance, type and condition of physical line, and other environmental factors. For example, if the distance to the Telco switch is great (6000 foot maximum), or the line is old, you may need a

Central Site Remote Access Switch 125