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Ethernet 10/100/1000Base-T and 100Base-T4 Crossover

This cable can be used to cascade hubs, or for connecting two Ethernet stations back-to-back without a hub. It works with 10Base-T, 100Base-TX, 100Base-T4 and 1000Base-T. Use a good enough cable, if you are confused about categories of cables then use category 5e(nhanced) and you'll be fine even at 1000Base-T.

RJ45 FEMALE CONNECTOR (To network interface card 1).
RJ45 FEMALE CONNECTOR (To network interface card 2).

RJ45 MALE CONNECTOR to network interface card 1.
RJ45 MALE CONNECTOR to network interface card 2.

(1000Base-T names in parentheses)

Name NIC1 Color NIC2 Name
TX+ (BI_DA+) 1 White/Orange 3 RX+ (BI_DB+)
TX- (BI_DA-) 2 Orange 6 RX- (BI_DB-)
RX+ (BI_DB+) 3 White/Green 1 TX+ (BI_DA+)
- (BI_DC+) 4 Blue 7 - (BI_DD+)
- (BI_DC-) 5 White/Blue 8 - (BI_DD-)
RX- (BI_DB-) 6 Green 2 TX- (BI_DA-)
- (BI_DD+) 7 White/Brown 4 - (BI_DC+)
- (BI_DD-) 8 Brown 5 - (BI_DC-)

That means that the white/orange cable connected to NIC 1 pin 1 should go to NIC 2 pin 3 and NIC 1 pin 2 to NIC 2 pin 6 etc.

Note 1: It's important that each pair is kept as a pair. TX+ & TX- must be in the pair, and RX+ & RX- must together in another pair. (Just as the table above shows).

Note 2: While 10Base-T and 100Base-TX only uses 2 pairs, please connect all four since 100Base-T4 and 1000Base-T needs them and save yourself some future debugging :)

Note 3: The colors originate from the numbering and name on NIC1.

Contributors: Joakim Ögren, Niklas Edmundsson, Jim C?, Jason D. Pero, Oscar Fernandez Sierra, Cayce Balara, Jeffrey R. Broido, Patrick Smart, Jeffrey R. Broido, Kim Scholte

IEEE Std 802.3, 2000 Edition

Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-07