Cables and Tools for the Network

 We are using the UTP, STP, fiber-optic and coaxial cables as the physical medium. Let's discuss each type of cables.

Coaxial Cables 

    This as an obsolete type of cable used in earlier days. It is having 2 conductors centered around single axes and separated by a shield.They have Radio Grade rating (RG) and hence starts with RG numbers.They have impedance rating in ohms. In old days RG58 cable with a BNC connector joined to a T connector was used to connect computers in a daisy chain manner.
     






   Now a days you can see RG6 coaxial cables, if you are using a cable modem. It is having a F-Type connector and having 75 ohm impedance.

UTP and STP cables

       Unshielded Twisted Pair (UTP) cables are the most commonly used network cable. They have 4 pairs of cables in a twisted manner. UTP cables usually having CATegory rating. The Cat3 cables used in old days was able to carry data at 10Mbps and a maximum 100 meter distance. They are running at a maximum of 16 MHz. CAT5 runs at 100 MHz and carries 100Mbps. CAT5e runs at 100 MHz, but can support 1Gbps as well. CAT6 runs at a maximum of 250 MHz and provides band width of 1 Gbps and CAT6a runs at a maximum of 500 MHz frequency, and provides 10Gbps bandwidth at distance of 100m. CAT6 also provides 10Gbps, but for shorter distance. CAT 7 operates at maximum of 600MHz and supports 10Gbps with low noise ratio.

          Unlike UTP the STP will have a shield to separate the pairs and thus reducing the signal interference between the pairs. 

STP

UTP

              We are using RJ-45 connector for both UTP and STP. We will discuss  the cabling details later. Another thing you can notice regarding twisted pair cable is the fire rating. The basic fire rating is the PVC, which is equivalent to no fire rating and hence very cheap. The next level of fire rating is riser, which is primarily used between the floors of Building. The highest rating is plenum. If there is any regulations by the authority in particular areas, you have to look in to the fire rating as well.

Fiber Optic Cable

  A fiber optic cable will have a fiber optic that carries the light, surrounded by a cladding used to reflect the light and keep it in the fiber itself and a jacket outside to protect the entire setup.

     There are two types of fiber cables we are using, the multi-mode and the single-mode. The multi-mode carries the LED lights and usually used for shorter distance. The single-mode carries laser beam and used for longer distance.   The fiber optic diameter for a single-mode cable is narrower than the multi-mode. Multi-mode cables are almost always in orange and single-mode almost always in yellow color. The fiber cables having two connectors. The multi-mode cables in the beginning was using an ST connecter that you can insert and twist to plug in. Another old type connector is the SC connector in square. FC is another type of connector that you can insert like a cable TV cable. All these 3 connectors are old and having two connectors needed in each end. In newer connectors these two connectors combined in to single connector. LC connector and MT-RJ connectors combines 2 cables in to single connector.

LC

MT-RJ

      

FC

SC

            


     Based on the polishing method the connectors are divided in to 3 categories. The physical contact connector (PC), Ultra physical contact connector (UPC) and angled physical contact connector (APC). 

PC

UPC

APC

Structured Cabling

            In this section I just want to familiarize the tools and terms used in a structured cabling. The structured cabling refers to the complete system of cabling and associated hardware for a building or campus.

           In an office environment you can see that your PC is connected to a wall outlet RJ 45. That wall outlet is connected to a patch panel in the MDF (Main Distribution Frame) or in the IDF (Intermediate Distribution Frame) and from there it connected to a switch through a patch cord. Also you can see all your patch panels and switches are fitted in to a rack. All these hardware is part of the structured cabling system. There are some standards for structured cabling. I will discuss the TIA standard for structured cabling.

           As we said Earlier RJ 45 jack is used to crimp the UTP cable to make the patch cables that connects the PC to wall outlet and switch to patch panel. There are 2 standards for these crimping, the TIA 568A and 568B. If you strip the insulator from the UTP cable you can see four pairs inside. The Orange, Blue, Green, Brown and Their corresponding whites. If you take the RJ45 connector facing the contact pins, you can number them from left to right as 1-8. The TIA 568A and 568B defines the order of each individual cable. The pins 1, 2, 3 and 6 are actually used in the network communication. 1,2 are transmission pairs

        TIA568B                                            TIA568A

1.   Orange White                                     1.Green White

2.   Orange                                              2.Green

3.   Green White                                       3.Orange White

4.   Blue                                                  4.Blue

5.   Blue White                                         5.Blue White

6.   Green                                                6.Orange

7.   Brown White                                       7.Brown White

8.   Brown                                                8.Brown

                     We can use crimping tool to create the patch cords. If you use same standard in both ends, that cable is called as straight through cable and if you use 568A in one side and 568B in the other, that cable is called as a crossover cables. Crossover cables are used to connect similar device and straight through for dissimilar devices. You can use straight through cables to connect the modern switches together, as they have ability to sense it and convert internally.

RJ45

Crimping Tool

                                  


         To connect the wall outlet to the patch panel through the UTP cable, we use 110 punch down. There is a CAT rating for the patch panel and connectors as well. You can use 110 punch down tool to punch the UTP cable to the patch panel and RJ45 outlet. The color code will be displayed on the patch panel and RJ45 outlet as per the appropriate TIA standard.

Patch Panel and punch down blocks

Punch Down Tool

 

Testing UTP Cables

                     Wiremap tester is the cheap and popular cable tester to test the continuity. This device consists of two parts. It generates signal at one end and that detected by the other end. It gives simple light indicators to show what is wrong.

          Another popular device is fluke networks microscanner. It will help to identify the cable breaks.

 

                              Usually network wall outlets are labelled to identify the patch panel port in to which it is connected. There will be situations like somebody forgot to label or the existing label damaged and not readable like that. In that situation we need to identify the corresponding patch panel port. We can use a toner and probe to identify the exact port. You can plug the probe in to the wall outlet and use the toner in the MDF or IDF room to get a tone, when you touch the corresponding cable with the toner.