Card, Adapter Card, and Port Command Reference
Page 118 7705 SAR OS Interface Configuration Guide
loopback (DS1)
Syntax loopback {line | internal | fdl-ansi | fdl-bellcore | payload-ansi}
no loopback
Context config>port>tdm>ds1
Description This command puts the specified port or channel in a loopback mode.
A line loopback loops frames received on the corresponding port or channel back towards the
transmit (egress) direction before reaching the framer. The bit stream is not reframed. The electrical
signal is regenerated by the Tx line interface unit (LIU) and the timing is provided by the Rx LIU.
An internal loopback loops the frames from the local router back at the framer. This is usually
referred to as an equipment loopback. The Tx signal is looped back and received by the interface.
The fdl-ansi loopback command sends a repeating 16-bit ESF data link code word to the remote end
requesting that it enter into a network line loopback. The ansi keyword enables the remote line FDL
ANSI bit loopback on the T1 line, in accordance with the ANSI T1.403 specification.
The fdl-bellcore loopback command sends a repeating 16-bit ESF data link code word to the remote
end requesting that it enter into a network line loopback. The bellcore keyword enables the remote
line FDL Bellcore bit loopback on the T1 line, in accordance with the Bellcore TR-TSY-000312
specification.
The payload-ansi loopback command sends a repeating 16-bit ESF data link code word to the remote
end requesting that it enter into a network payload loopback. A payload loopback loops frames back
towards the transmit (egress) direction after reaching the framer. The bit stream is reframed. The
electrical signal is regenerated by the Tx LIU and the timing is provided by the Rx LIU.
The loopback command is not saved to the system configuration.
The no form of this command disables the specified type of loopback.
Default no loopback
Parameters line — places the associated port or channel into line loopback mode
internal — places the associated port or channel into internal loopback mode
fdl-ansi — requests an FDL line loopback in accordance with the ANSI T1.403 specification
fdl-bellcore — requests an FDL line loopback in accordance with the Bellcore TR-TSY-000312
specification
payload-ansi — requests a payload loopback using ANSI signaling
Note: The fdl-ansi, fdl-bellcore and payload-ansi options can only be configured if DS1
framing is set to ESF.
To Next Page
Loading...
