RJ

RJ-45 Crossover Cable and Straight Through Pinouts

Overview
This article provides connectivity examples for hub-to-hub, hub-to-transceiver, transceiver-to-transceiver, pinouts and color coding for standard ethernet cabling.

Discussion

Crossover Cable
RJ-45 PIN	RJ-45 PIN
1 Rx+	3 Tx+
2 Rc-	6 Tx-
3 Tx+	1 Rc+
6 Tx-	2 Rc-

Straight Through Cable
RJ-45 PIN	RJ-45 PIN
1 Tx+	1 Rc+
2 Tx-	2 Rc-
3 Rc+	3 Tx+
6 Rc-	6 Tx-

Please Note: The standard connector view shown is color-coded for a straight thru cable assembly, when connecting Hub to Xcvr or DNI Card. When connecting hub to hub, Xcvr to Xcvr, or DNI to DNI, the wires must crossover at the opposite end of the cable assembly.

Interconnecting Your Hubs, Transceivers, and DNI Cards

As noted in the illustrations below, a crossover cable is required when connecting a Hub to a Hub, or a Transceiver to Transceiver, or DNI to DNI card, or Transceiver to DNI card. When connecting a Hub to a transceiver or DNI card, a straight through cable is always used. Please Note: Some Cabletron products are equipped with internal switches that can internally cross the twisted pairs.

In these illustrations a Hub can refer to any standalone product, such as the SEHI or MicroMMAC; or concentrator modules in MMAC-FNB or MMACPLUS hubs, such as a TPMIM-xx, TPRMIM-xx or 9E132-15. To note the differences between Ethernet, Token Ring and FDDI/ATM connectivity, refer to the Wiring Color Code Standards.

Hub to Hub Connectivity

Hub to Transceiver or DNI Card Connectivity

Transceiver to DNI Connectivity

Standard Ethernet Cable Part Numbers

9360005-xx	Straight Through Cable, Cat 5	Hub to Xcvr or DNI
9360141-xx	Straight Through Cable, Cat 3	Hub to Xcvr or DNI
9360034-xx	CrossOver Cable, Cat 3	Hub-Hub, Xcvr-Xcvr, DNI-DNI
9360169-xx	CrossOver Cable, Cat 5	Hub-Hub, Xcvr-Xcvr, DNI-DNI

Category 5 wiring standards:

EIA/TIA 568A/568B and AT&T 258A define the wiring standards and allow for two different wiring color codes.

Pin #	EIA/TIA 568A	AT&T 258A, or EIA/TIA 568B	Ethernet 10BASE-T	Token Ring	FDDI, ATM, and TP-PMD
1	White/Green	White/Orange	X		X
2	Green/White	Orange/White	X		X
3	White/Orange	White/Green	X	X
4	Blue/White	Blue/White		X
5	White/Blue	White/Blue		X
6	Orange/White	Green/White	X	X
7	White/Brown	White/Brown			X
8	Brown/White	Brown/White			X

Pairs may be solid colors and not have the stripe.
Category 5 cable must use Category 5 rated connectors.

100baseT Straight Cable (PC to HUB/SWITCH)

Straight cables are used to connect PCs or other equipment to a HUB or Switch. If your connection is PC to PC or HUB to HUB you MUST use a Crossed cable.

The following cable description is for the wiring of BOTH ends (RJ45 Male connectors) with your category 5 wiring colors (TIA/EIA 568A or 568B though the example uses 568B colors).

Pin No.	strand color	Name
1	white and orange	TX_D1+
2	orange	TX_D1-
3	white and green	RX_D2+
4	blue	BI_D3+ **
5	white and blue	BI_D3- **
6	green	RX_D2-
7	white and brown	BI_D4+ **
8	brown	BI_D4- **

We use BLUE for 100baseT straight cables.

NOTE 1: Wires marked ** are ABSOLUTELY NECESSARY for 100Base-T4 networks (using any combination of category 3/4/5 cables) but are not required for 100Base-TX (using cat 5/5e ONLY cables) and CAN be used for other purposes e.g. telephony

NOTE 2: All our wiring is now done to the 100baseT spec which you can use with 10baseT networks - but NOT the other way around.

100baseT Crossed cable (PC to PC or HUB to HUB)

Crossed cables are used to connect PCs to one other PC or to connect a HUB to a HUB. If your connection is PC to HUB you MUST use a Straight cable.

The following description shows the wiring at both ends (male RJ45 connectors) of the crossed cable.

We use RED for crossed cables (or more commonly now a red heat-shrink collar at each end). NOTE: All our crossed wiring is now done to the 100baseT spec which you can use with 10baseT networks - but NOT the other way around.

GIGABIT ETHERNET (1000BASE-T) CROSSOVER
Plug A			Plug B
Pin #	Signal	Conductor Color Code	Pin #	Signal	Conductor Color Code
1	BI_DA+	white/green	1	BI_DA+	white/orange
2	BI_DA-	green	2	BI_DA-	orange
3	BI_DB+	white/orange	3	BI_DB+	white/green
4	BI_DC+	blue	4	BI_DC+	white/brown
5	BI_DC-	white/blue	5	BI_DC-	brown
6	BI_DB-	orange	6	BI_DB-	green
7	BI_DD+	white/brown	7	BI_DD+	blue
8	BI_DD-	brown	8	BI_DD-	white/blue
Legend: N/U - Not used. May be either short or open circuit

Rolled Cable {Cisco speak}

In a rolled cable, the colored wires at one end of the cable are in the reverse sequence of the colored wires at the other end of the cable.the 8-port RJ-45 adapter that is used with the Cisco 2509, 2510, 2511, and 2512, is the same as a rolled cable

Rolled Cable