ADTRAN DE-4E specifications Installation, Time Slot Allocation, Protected Loopback

The FT1 Digital Subscriber Loop (DSL) local loop operates as an independent subsystem, over a single twisted pair. The FT1 DP communicates over this twisted pair to the Fractional Network Interface Device (FNID) and/or FT1 repeater listed below:

Part Number	Unit Description
1242041LX	T400	FNID Circuit Pack
1245201LX	T200	FNID Circuit Pack
1242042LX	T400	FNID Standalone
1242050L2	FT1 Repeater
1245211LX	FT1 Repeater

The payload between FT1 DP and FNID is programmable from the faceplate rotary switch as follows:

2 channels (minimum)	128 kbps
3 channels	192 kbps
4 channels	256 kbps
5 channels	320 kbps
6 channels	384 kbps
7 channels	448 kbps
8 channels	512 kbps
9 channels	576 kbps
10 channels	640 kbps
11 channels	704 kbps
12 channels (maximum)	768 kbps

The system carries a small amount of overhead used for maintenance and performance monitoring related functions.

NOTE

Changing the number of DS0s does not affect unit provisioning.

2. INSTALLATION

C A U T I O N !

SUBJECT TO ELECTROSTATIC DAMAGE

OR DECREASE IN RELIABILITY.

HANDLING PRECAUTIONS REQUIRED.

After unpacking the unit, inspect it for damage. If damage is noted, file a claim with the carrier, then contact ADTRAN. See Warranty and Customer Service.

The FT1 DP plugs directly into a Nortel DE-4E shelf. The unit occupies a single slot. No installation wiring is required.

Time Slot Allocation

The bandwidth may be taken by the FT1 DP in contiguous or alternating time slots. These slots must not have other channel cards plugged in the slots taken by the FT1 DP bandwidth. This will cause contention on the transmit side of the channel bank.

The FT1 will not wrap around the channels at the end of the channel bank. For example, if n is equal to 4 channels and the FT1 DP is plugged into slot 23 of the channel bank, then only channels 23 and 24 can be used, not channels 1 and 2.

Protected Loopback

Protected Loopback prevents false latching loopback occurrences when the latching loopback is embedded within the customer payload. This feature is enabled by setting SW1-8 to ON. See Table 1 for the latching loopback sequence requirement when Protected Loopback is enabled.

Table 1. Protected Loopback Mode Requirement

T1E1.2/99-007R1 (Latching Loopback)

Function
Sequence	Byte Code		# of Received
Bytes
Clear existing	Transition in progress		Minimum of 35
loopbacks	(TIP) X0111010		TIP bytes
Identify device	Loopback select		Minimum of 35
to be looped	code (LSC)		LSC bytes
	X1010101	- OCU
	X0110001	- CSU
	X1000001	- NI
Prepare loop,	Loopback enabled		Minimum of 100
send MAP code	(LBE) X1010110		LBE bytes
after 30 bytes
Activate	Far-end voice (FEV)		Minimum of 35
loopback	X1011010		FEV bytes

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

X = don't care bit.

Three switch packs (SW1, SW2, SW3) are used to configure the mode of operation for the unit. A definition of each switch is shown in Table 2 and Table 3. Configuration may be performed by manually selecting each option switch, or alternatively, set through the craft interface. Manual configuration must be performed before installing the unit into the channel bank.

2 Section 61245207L2-5, Issue 3 61245207L2-5C