ADTRAN T200 IDSL warranty LED Indication, Loopback Testing, Alternating Loopback Sequences

LED Indication

The IDSL OCU-R front panel LEDs display the operating status. The LEDs are described in Table 5.

	Table 5.	LED Indication
LED	Color	Description
SYNC	RED	Indicates that there is no network sync.
		Indicates network synchronization.
	GREEN
CRC	RED	ON indicates that there are CRC errors.
		OFF indicates no CRC errors.
NO DSU	YELLOW	ON indicates no signal, no sealing
		current, no SC framing.
		OFF indicates signal, sealing current, and
		SC framing achieved.
AP	GREEN	ON indicates that the unit has been
		remotely provisioned.
		FLASHING indicates remote control link
		active.
		OFF indicates locally provisioned
		operation.
NTWK LBK	YELLOW	ON indicates a loopback towards the
		network is invoked at RT's DDS
		Customer interface in response to Test
		Center issuing OCU loopback.
		FLASHING indicates loopback toward
		network is invoked at CSU/DSU via
		network commanded CSU loopback, and
		RT's response of reversing sealing current
		to CSU/DSU.
CUST LBK	YELLOW	ON indicates a loopback towards the
		customer is invoked at IDSL OCU-R
		interface via front panel LBK button.
		FLASHING indicates a loopback towards
		the customer is invoked at the ADTRAN
		U-BR1TE via IDSL OCU-R front panel
		LBK button.

4. TESTING

Loopback Testing

Loopback tests can be performed from the Central Office (CO) to verify proper loop and IDSL OCU-R operation. The IDSL OCU-R provides a network loopback in response to an OCU latching or non- latching loopback command. The IDSL OCU-R also provides a sealing current reversal when the CSU loopback command is detected. Alternating loopbacks may be performed at all rates, except 64 kbps Clear Channel. See Table 6 for alternating loopback sequences. See Table 7 for latching loopback sequences.

Table 6. Alternating Loopback Sequences

Sequence	Received Bytes
Function
Activate loopback	Four consecutive bytes of
	specified loopback code
	X0101010 - OCU
	X0101000 - CSU
	X0101100 - DSU
Maintain loopback and	Data byte alternating with
test for bit errors	loopback code
	example:
	XDDDDDD1/X0101010
Clear loopback	Four consecutive data bytes
	without CSU loopback code
X = Don't care bit

Table 7. Latching Loopback Sequences

Sequence			Number of
	Byte Code		Received
Function
			Bytes
Clear existing	Transition in		Minimum of
loopbacks	progress (TIP)		35 TIP bytes
	X0111010
Identify device to	Loopback select		Minimum of
be looped	code (LSC)		35 LSC bytes
	X0000101	- DS0
	X1010101	- OCU
	X0110001	- CSU
Prepare to loop;	Loopback enabled		Minimum of
send MAP code	(LBE)		100 LBE bytes
after 30 bytes	X1010110
			Minimum of
Activate	Far-End voice		32 FEV bytes
loopback	(FEV)
	X1011010

Minimum of 35 TIP bytes required to disable established latching loopback.

X = Don't Care bit

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