Nortel Networks 1750 manual T1/E1 CSU/DSU cable pinouts for crossover connection

88Appendix A Technical specifications

Use cable that is wired in accordance with EIA-568-A wiring style. This wiring style ensures that a twisted pair inside the patch cord carries the transmit signal (pins 4 and 5) and the receive signal (pins 1 and 2). Nortel strongly recommends that you use professionally manufactured patch cords.

Connect the T1/E1 CSU/DSU WAN interface card to the service provider network by using a straight-through cable or a crossover cable, depending on how the service provider wired the jack:

•For a straight-through connection, you can use a standard category 5 (Ethernet) straight-through cable.

•For a crossover connection, you cannot use a standard category 5 crossover cable. Do not interchange the T1/E1 CSU/DSU crossover cable and the Ethernet crossover cable.

The following table provides the T1/E1 CSU/DSU cable pinouts for a crossover connection.

Table 29 T1/E1 CSU/DSU cable pinouts for crossover connection

Standard-wired		Pair number	Special-wired
end 8-pin male	Signal name	and conductor	end 8-pin male
1	RXDA<-TXDA	wht/org pair 2A	5
2	RXDB<-TXDB	orange pair 2B	4
3	Not used	wht/grn pair 3A	3
4	TXDB->RXDB	blue pair 1B	2
5	TXDA->RXDA	wht/blu pair 1A	1
6	Not used	green pair 3B	6
7	Not used	wht/brn pair 4A	7
8	Not used	brown pair 4B	8

The cable operates properly if you do not connect pins 3, 6, 7, and 8.

Caution: For crossover connections, do not use Ethernet cable. If you use Ethernet cable, the T1/E1 CSU/DSU does not work to specifications, and this condition can corrupt data.

NN46110-316 03.01