XtendLan XL-GDB102E, User Manual, Page: 91 / 105

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For E1 Interface model as CPE side, there have: Local Digital, remote line, remote payload,
farend line and farend payload.
For Serial Interface model as CPE side, there have: Local Digital, remote line, remote
payload, farend line, farend payload and V.54.
If the device haven’t connect or under handshake, there will not have farend line, farend
payload and V.54.There are no diagnostic function on Ethernet interface model.
Stand alone NTU, no connection with other NTU:
E1 interface
CO side
Serial interface
CO side
Local Digital Local Digital
Local Local
Remote line Remote line
Remote payload Remote payload
E1 interface
CPE side
Serial interface
CPE side
Local Digital Local Digital
Remote line Remote line
Remote payload Remote payload
After connection both CO side and CPE side:
E1 interface
CO side
Serial interface
CO side
Local Digital Local Digital
Local Local
Remote line Remote line
Remote payload Remote payload
Farend line Farend line
Farend payload Farend payload
V.54
E1 interface
CPE side
Serial interface
CPE side
Local Digital Local Digital
Remote line Remote line
Remote payload Remote payload
Farend line Farend line
Farend payload Farend payload
V.54
Definition of V.54
An ITU standard (1976) for various loopback tests that can be incorporated into modems
for testing the telephone circuit and isolating transmission problems.
Operating modes include local and remote digital loopback and local and remote analog loopback.