Configuring T1 Physical link
cablelength command allows you to control the transmitter signal level for your conditions. Typically, your service provider will suggest the correct level.
For short haul connections (less then 700 feet) the typical equipment uses less sensitive receivers. The transmitter level is usually set by selecting a cable length in feet, from the following values: 133, 266, 399, 533 or 655. Choose the next higher value if your cable length does not match one of the values. For example, choose 133 for a 50 foot cable and 533 for a 450 foot cable. The default value is 133, which corresponds to cables in the range of
For longer distances (up to 6000 feet) the typical equipment uses more sensitive receivers, and crosstalk is more likely to occur. Under these conditions, the transmitter level is set by selecting a transmitter attenuation level in dB from the following values:
From lowest to highest transmitter level, use the following values for the config port t1 cablelength command:
To configure the cable length, use one of the following commands:
config ports <portlist> t1 cablelength [0
CLOCK SOURCE
A clock is used to synchronize data transmission on the line. Generally, one end of the T1 link provides the master clock, and the other end of the link recovers the clock from the signal on the line. By default the clock source is derived from the line. If needed, an internal clock is available. To configure the clock source, use the following command:
config ports <portlist> t1 clocksource [internal line]
Note: If the clock source is configured as “line”, but the clock cannot be recovered from the signal on the line, the hardware will use the internal clock instead.
Facility Data Link
Facility data link (FDL) uses twelve bits in the ESF frame to signal information about line and connection status. Since FDL is only meaningful for ESF framing, FDL settings