# path ds1|e1 loopback

#### Syntax

path pathChannel { ds1 | e1 } tributaryIdentifier loopback
{ local | network { line | payload } }

no path pathChannel { ds1 | e1 } tributaryIdentifier loopback

path pathChannel ds1 tributaryIdentifier loopback remote
{ line fdl { ansi | bellcore } | payload [ fdl ] [ ansi ] }

no path pathChannel { ds1 | e1 } tributaryIdentifier loopback remote

#### Release Information

Command introduced before JunosE Release 7.1.0.

#### Description

Configures a loopback at the DS1/E1 over SONET/SDH VT layer on channelized SONET and SDH interfaces. The no version turns off the loopback.

#### Options

- pathChannel—Number, in the range 1–2147483648, that identifies the path
- tributaryIdentifier—Specifier for the tributary in the format
  pathChannel { ds1 | e1 } pathPayload/tributaryGroup/tributaryNumber
  - pathPayload—Payload number for the path; value is 1 for SONET and in the range 1–3 for SDH
  - tributaryGroup—Number, in the range 1–7, that identifies the group within the path
  - tributaryNumber—Number of the tributary within the tributary group; the value is in the range 1–4 if the tributary type is vt15 or tu11 and in the range 1–3 if the tributary type is tu12
- local—Loops the router output data back toward the router at the T1/E1 framer; on supported line modules also sends an alarm indication signal (AIS) out toward the network.
- network { line | payload }—Specify the line keyword to loop the data back toward the network before the T1/E1 framer and automatically set a local loopback at the HDLC controllers. Specify the payload keyword to loop the payload data back toward the network at the T1/E1 framer and automatically set a local loopback at the HDLC controllers.
- remote line fdl ansi (T1 line only)—Sends a repeating 16-bit ESF data link code word (00001110 11111111) to the remote end requesting that it enter into a network line loopback. Specify the ansi keyword to enable the remote line FDL ANSI bit loopback on the T1 channel, according to the ANSI T1.403 specification.
- remote line fdl bellcore (T1 line only)—Sends a repeating 16-bit ESF data link code word (00010010 11111111) to the remote end requesting that it enter into a network line loopback. Specify the bellcore keyword to enable the remote line FDL Bellcore bit loopback on the T1 channel, according to the Bellcore TR-TSY-000312 specification.
- remote payload [ fdl ] [ ansi ] (T1 line only)—Sends a repeating 16-bit ESF data link code word (00010100 11111111) to the remote end requesting that it enter into a network payload loopback. Enables the remote payload FDL ANSI bit loopback on the T1 channel. You can optionally specify fdl and ansi, but it is not necessary.

  | Note: You cannot send an inband pattern to the remote end requesting that it enter into a network line loopback.

#### Mode

Controller Configuration