Configuring the T1 Physical Link
are ignored when a port is configured for SF framing. See “Framing” for information on configuring framing.
The two standards supported for FDL are ATT, described by the ATT 54016 specification, and ANSI, described by the T1.403 standard. The default value is off. To configure FDL, use the following command:
config ports <portlist> t1 fdl [off att ansi]
Framing
Framing is used to synchronize data transmission on the T1 line. Framing allows the hardware to determine when each packet starts and ends. The two choices for framing are Super Frame (SF), also known as D4, and Extended Super Frame (ESF). The ESF scheme is a newer standard and is enabled by default. To choose the framing scheme, use the following command:
config ports <portlist> t1 framing [esf sf]
If you choose to use SF framing, you should disable yellow alarm detection for the T1 line. SF framing may generate false yellow alarms. See “Yellow Alarms” on page
Inband Loopback Detection
When inband loopback detection is enabled, a specific sequence of data in the signal payload from the remote end of the T1 link will cause the local end to enter network line loopback mode and send any received signal back to the remote end. Inband loopback detection is only possible if the FDL standard is configured as ATT. See “Facility Data Link” on page
config ports <portlist> t1 lbdetect [off inband]
Linecoding
Linecoding is the convention used to encode signals for transmission over the T1 line. You can choose from two linecoding standards, bipolar eight zero suppression (B8ZS) or alternate mark inversion (AMI). The default value is B8ZS. To configure linecoding, use the following command:
config ports <portlist> t1 linecoding [b8zs ami]