Framing—either SONET or SDH; default is SONET.
Clock source—either internal or line; default is line.
J0 section trace string—16-character string; default is the IEEE default value, which has no string representation.
J1 path trace string—16-character string; default is the IEEE default value, which has no string representation.
Loopback—line, internal, or off; the default is off
On Summit X480 series switches:
configure ports port_list wan-phy loopback {off | internal | line}