Straight,Crossover cable and Rollover Cable

Common Ethernet network cables are straight, crossover cable and roll over. This Ethernet network cable is made of four pair high performance cable that consists twisted pair conductors that used for data transmission. Both end of cable is called RJ45 connector. The colour of wires are orangewhite,orange,greenwhite,green,bluewhite,blue,brownwhite,brown.
The cable can be categorized as Cat 5, Cat 5e, Cat 6 UTP cable. Cat 5 UTP cable can support 10/100 Mbps Ethernet network, whereas Cat 5e and Cat 6 UTP cable can support Ethernet network running at 10/100/1000 Mbps. Cat 3 UTP cables are not popular anymore since it can only support 10 Mbps Ethernet network.
Straight,crossover cable and roll over can be Cat3, Cat 5, Cat 5e or Cat 6 UTP cable, the only difference is each type will have different wire arrangement in the cable for serving different purposes.

Straight Cable

You usually use straight cable to connect different type of devices. This type of cable will be used most of the time and can be used to:
1) Connect a computer to a switch/hub's normal port.

2) Connect a computer to a cable/DSL modem's LAN port.

3) Connect a router's WAN port to a cable/DSL modem's LAN port.

4) Connect a router's LAN port to a switch/hub's uplink port. (normally used for expanding network).

5) Connect 2 switches/hubs with one of the switch/hub using an uplink port and the other one using normal port.
If you need to check how straight cable looks like, it's easy. Both side (side A and side B) of cable have wire arrangement with same color.

Crossover Cable

Sometimes you will use crossover cable, it's usually used to connect same type of devices. A crossover cable can be used to:
1) Connect 2 computers directly.

2) Connect a router's LAN port to a switch/hub's normal port. (normally used for expanding network).

3) Connect 2 switches/hubs by using normal port in both switches/hubs.
In you need to check how crossover cable looks like, both side (side A and side B) of cable have wire arrangement with following different color .

Roll Over Cable
This roll over cabling is just opposite to Straight Cabling

Side A Side B
Orange White Brown
Orange Brown White
Green White Green
Blue Blue White
Blue White Blue
Green Green White
Brown White Orange
Brown Orange White

How to Make CROSS & STRAIGHT cable

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STEP 1: Choose the right cable…
1. To Connect PC to PC Cross Cable.

2. To Connect PC to HUB/SWITCH/ROUTER Straight Cable.

3. To Connect HUB/SWITCH/ROUTER to HUB/SWITCH/ROUTER Straight
Cable

STEP 2: Understanding CAT 5 Cables…

Wires: CAT 5 Cable has 4 pairs of copper wire inside it.

Colors: Standard cables has BROWN, BROWN WHITE, GREEN, GREEN-
WHITE, BLUE, BLUE WHITE, ORANGE, ORANGE WHITE.

STEP 3: Making Straight Cable…

Nomenclature: let us first give a number scheme for cabling which we will
follow throughout this tuto. BROWN (8), BROWN WHITE (7),
GREEN (6), GREEN WHITE (3), BLUE (4), BLUE WHITE (5),
ORANGE (2), ORANGE WHITE (1)

Requirements: Two RJ45 Connectors, Crimping tool & CAT 5 cable of desired
length(less than 250 meters).

STEP 3.1:

There are two standards adopted for Cabling EIA/TIA 568A & EIA/TIA 568B.

When you use single standard (either EIA/TIA 568A or EIA/TIA 568B) on both the end of cable then the resulting cable is STRAIGHT CABLE.

On the other hand if you use different cabling standard on the ends of cable then the resulting cable is CROSS CABLE

I’ll use EIA/TIA 568B standard for creating cross and straight cable

1. Remove the covering of CAT 5 cable.
2. Straighten the eight wires of the cable.
3. Using Crimping tool’s cutter cut the end of wires so that they are of same length
4. Arrange the wire in order 1, 2, 3, 4, 5, 6, 7 & 8 respectively as I have mention or as shown in the diagram.
5. Insert the arranged cable in the RJ45 connector with clip pointing down exactly as shown in the figure.
6. In crimping tool insert the head of RJ45 connector and crimp (press) it hardly.
7. Follow same step with same color order for the other end of cable too.
8. The wire you made by following these steps is a STRAIGHT cable.

STEP 4: Making CROSS Cable…

Of the Eight wires in Cat 5 not all are used for data transfer when using 100Mbps Ethernet card. Only 2 pairs of cable are used i.e. 2 wire for transmitting signal and two wires for receiving signal.

So now you can guess why we have to make CROSS CABLE for connecting same kind of devices. Because if use same color coding on both the side than transmitter of one m/c will send data to transmitter of another and data packets will lost, so we have to change wiring code so that transmitter of one connects to reciver of other and vice-versa.

Here are the Steps:
Steps 1 to 6 are same as for STRAIGHT through cables
7. Only difference is in color coding of other side of wire.
8. Wire that is on 1st number on A-side (one end) should be on 3rd number on B-
side (other side) & vice-versa.
9. Wire that is on 2st number on A-side (one end) should be on 6rd number on B-
side (other side) & vice versa.
10. Now Crimp the RJ45 connector.
11. Your CROSS wire is completed.

How to Cabling Your Network

There are two main ways of connecting PCs together to form a network. There are others, but for now, we will consider only the Ethernet alternatives:

• Coaxial Ethernet

Coaxial ethernet is really a fading concept. Two types are available, Thick-wire and Thin-wire. Thick-wire is very unlikely to be found on modern networking equipment but thin-wire is fairly common. Thin-wire ethernet consists of lengths of 50ohm coax cable that are terminated in BNC bayonet connectors. Thin-wire compatible equipment sport a round barrel that the coax is plugged into. Unfortunately, connecting thin-wire is not always so simple. It is important that a thin-wire cable is correctly terminated and not all thin-net NICs are able to automatically terminate a cable. In this case, it is necessary to use a t-piece c/w a terminator so that a cable impedance of 50ohm is maintained. Failure to observe this will result in communication problems between the network devices.

Note: Thin-wire ethernet is also known by it's technical notation of 10base2.

• TP Ethernet

TP, or Twisted Pair Ethernet is the modern equivalent of 10base2 cable systems. Far more flexible, neater and less prone to network faults, TP appears on a myriad of networking and communications equipment. If you have your single PC already connected to your CM then you are already using RJ45 TP cabling and it will almost probably feature in your network. CAT5 cable consists of 4 pairs of wires, with each pair being two insulated copper wires twisted together. These 'twisted-pairs' are then sheathed in a plastic outer sleeve that come in a variety of colours, although 'computer' beige is probably the most common;-). The standards for ethernet over Cat5 cabling define a maximum length of 100 metres for operation at 10MBps, but in practice it is perfectly possible to extend this maximum by 20 or 30 metres without detriment to network communication.

RJ45 refers to the connector that is crimped onto the end of the CAT 5 cable. The connector is rectangular in shape and has a tab at the top. The cable is inserted so that the tab latches onto a small recess in the socket, rather like the side latch on the ubiquitos BT telephone plug.

Almost all of the network set-ups featured on this site use RJ45 cabling exclusively, with each cable being of the 'straight' type. Where necessary, x-over cables are also employed. The following diagrams show how the two types of ethernet detailed above can be used in a network, with straight RJ45 cables depicted by BLUE lines and cross-overs in RED. Thinwire Co-ax cable is shown in grey.

Connecting a Single PC to a CM connected PC

• With Thinwire

For this set-up a single piece of thinwire co-ax is used to connect two PCs, with each end of the cable physically connected to a T-piece, with the 'spare' connector capped with a terminator to maintain the cable impedance.

It is important to use the correct cable type for thinwire so that the impedance is correct. The official designation is RG58.

• With RJ45

Where two PCs are connected using an RJ45 cable, a cross-over cable needs to be used. An RJ45 cross-over cable actually crosses the transmit and receive pairs in the cable so that one NICs transmit connects to the other NICs receive, and vice versa.

Connecting Multiple PCs to a CM connected PC

• With Thinwire

To add additional clients to the network, remove one of the t-pieces and connect another thinwire coax cable to the vacant connector and replace the terminator at the t-piece of the last device.

Note that some network cards have an on-board termination setting.

• With RJ45

In an RJ45 cabled network, adding additonal clients requires the use of an intermediary device such as a hub or a switch. PCs connect to the hub/switch using straight cables and these are, in turn, connected internally within the hub or switch.

In this environment, there is no requirement for RJ45 cross-over cables.

Straight v. X-over Cables

The requirement for RJ45 cross-over, or x-over, cables is dictated by the type of devices that are being connected. There are two interface types associated with networking equipment, DTE (Data Terminating Equipment) and DCE (Data Communications Equipment). DTE devices mainly consist of PC NICs and Routers. When connecting a DTE device to a DCE device, e.g., a PC to a Hub, a straight cable is required. When the two connecting devices have the same interface type, i.e., both DCE or both DTE, then a x-over cable is necessary.

Device	I/F Type	Device	I/F Type	Cable Type
PC	DTE	Hub Port	DCE	Straight
PC	DTE	Cable Modem	DCE	Straight
PC	DTE	PC	DTE	X-Over
Hub Port	DCE	Hub Port	DCE	X-over

Unfortunately, these examples do not constitute hard and fast rules. Some Cable Modems, especially those integrated in Set-Top Boxes, have DTE interfaces, so any PC or Router that connects to it will need a x-over cable. Also, when connecting two hubs together a x-over cable may not be necessary if one of the hubs has an uplink port. An uplink port will have a DTE type interface, so a straight cable can be used to connect to another DCE port, such as a hub port. On many hubs, one of the ports may have a port that is switchable between DCE and DTE. This function can be manual, so a switch has to be activated, or an interface can auto-detect what type of interface it needs to be.

The following diagram shows the necessary cabling required for both straight and x-over CAT5 cables. Each of the four pairs in a cable are colour coded for easy identification, although the colours may vary between different cables.

The Tx and Rx refer to Transmit and Receive respectively, with the + and - symbols refering to the polarity of the signals. A DTE device will transmit data using cables 1 and 2, whilst a DCE device will transmit on Pins 3 and 6. The transmit cables at one end must be connected to the receive cables at the other end for the connection to work. When constructing cables, it is important that the polarities are maintained so that the cable is not affected by interference.