10baseT 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. Crossed cables are sometimes called Crossover, Patch or Jumper cables. 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.

One end RJ45 Male	Other end RJ45 Male
1	3
2	6
3	1
4 *	5 *
5 *	4 *
6	2
7 *	8 *
8 *	7 *

NOTES:

1. Items marked * are not necessary for 10M LANs but since you will be moving shortly to 100MB LANs (won't you) you will save yourself a LOT OF TIME finding crappy cable (that you made) that does not work. Instead we suggest you wire to 100BaseT standards.
2. We use RED for crossed cables (or more commonly now a red heat-shrink collar at each end).
3. All our crossed wiring is done to the 100base-T4 spec which you can use with 10baseT networks - but NOT always the other way around.

10baseT 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 the 568B category 5(e) wiring colors you could, of course, use the 568A colour scheme.

Pin No.	strand color	Name
1	white and orange	TX+
2	orange	TX-
3	white and green	RX+
4	NC	*
5	NC	*
6	green	RX-
7	NC	*
8	NC	*

NOTE: Items marked * are not necessary for 10M LANs (10base-T) but since you will be moving shortly to 100MB LANs (won't you) you will save yourself a LOT OF TIME finding crappy cable (that you made) that does not work. Instead we suggest you wire to 100Base-T4 standards. After all you gotta stick the ends somewhere man.

We use BLUE for 10base-T straight cables. NOTE: All our wiring is now done to the 100base-T4 spec which you can use with 10base-T networks - but NOT necessarily the other way around.

Category 5(e) (UTP) colour coding table

Category 5(e) (UTP) colour coding table

The following table shows the normal colour coding for category 5 cables (4 pair) based on the two standards supported by TIA/EIA.

These standards apply to the color code used within any SINGLE cable run - BOTH ENDS MUST USE THE SAME STANDARD. However, since they both use the same pinout at the connectors you can mix 568A and 568B cables in any installation.

Crossed and Straight cables - when to use them

The following diagram shows the Normal use of Crossed and Straight cables (see also the notes below).

Notes:

1. We show Straight cables as BLUE and Crossed as RED. That is our convention. The cable color can be anything you choose or, more likely, the vendor decides.
2. To avoid the need for Crossed cables many vendors provide UPLINK ports on Hubs or Switches - these are specially designed to allow the use of a STRAIGHT cable when connecting back-to-back Hubs or Switches. Read the manufacturers documentation carefully.
3.

Increasingly vendor hubs (can you still buy them) and switches will auto-detect the connection type and internally switch the connectors so that STRAIGHT cables can be used everywhere.

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Basic Lan Concepts

Basic Notes on Lan:

1. LAN cables are generically called UTP (Unshielded Twisted Pair) and are identified with a category rating. When installing new cable, unless there is a very good reason not to, you should be using category 5, 5e or 6 UTP which is rated for both 10 and 100mb LAN operation.

2. UTP comes in two forms SOLID or STRANDED. SOLID refers to the fact that each internal conductor is made up of a single (solid!) wire, STRANDED means that each conductor is made up of multiple smaller wires. Stranded cable (which is typically more expensive) has a smaller 'bend- radius' (you can squeeze the cable round tighter corners with lower loss) and due to its flexibility should be used where you plug and unplug the cable frequently. All other things being equal the performance of both types of cable is the same. In general, solid cable is used for backbone wiring and stranded for PC to wall plug (patch) cables. Beware: Each type of wire, solid or stranded, needs its own connector type.

3. There is NO excuse with all the choice of color cable and other techniques available to-day for not being able to visually spot the difference between at least a straight and a crossed cable before you spend 1 hour fitting the wrong cable into your network. For cheap-skates (which includes us) you can get heat-shrink colour tubing in a slew of colours which you fit on each end of the cable beside the connector to indicate the wiring type and standard instead of using different coloured cables. The advantage of this scheme is that when you change your wiring standard you can just change the sleeve colour - you don't have to rip out the cable. Disadvantage: You have to remember to put the tubing on BEFORE the connector!

4. You CAN use 100base-TX wiring with a 10base-T network (but not always the other way round). In general ALWAYS use 100baseTX/T4 wiring standards.

5. If you are using category 5, 5e or 6 wiring EVERYWHERE you can use the 100base-TX standard (this only uses 2 pairs , 4 conductors). Most of the information below assumes you are using category 5, 5e or 6 cables.

6. If you are using category 3 or 4 cables with 100M LANs ANYWHERE you MUST use the 100Base-T4 standard and this has ADDITIONAL RESTRICTIONS documented throughout (it uses all 4 pairs, 8 conductors). LAN connections/pinouts are defined by IEEE 802.3u.

7. Maximum LAN cable runs are 100 meters (~300ft).