Preamble:
This space will be utilized to synthesize my notes and help improve my learning process while I study for the CompTIA Network+ N10-009 certification exam. Please follow along for more Network+ notes and feel free to ask any questions or, if I get something wrong, offer suggestions to correct any mistakes.

Introduction to Structured Cabling

The networking industry has developed a standard model for deploying a structured cabling system. This model is adaptable to both small and large networks.

As you study this lesson, think of the following questions:

• What is the difference between the

  Main Distribution Frame (MDF) and an Intermediate Distribution Frame (IDF), and how do they relate to patch panels?

• When should you use stranded core twisted pair cable instead of solid core twisted pair?

• What is the difference between the T568A and T568B standards?

• When you use a punch down tool, which way should the blade face?

Structured Cabling System

A structured cabling scheme is a standard way of provisioning cabled networking for computers in an office building. The best-known standard is the ANSI/TIA/EIA 568 Commercial Building Telecommunications Wiring Standard. This standard identifies the following locations or subsystems within a structured cabling system:

• Work Area: This is the space where user equipment is located and connected to the network, usually with a patch cable plugged into a wall port.
• Horizontal Cabling: This connects user work areas to an Intermediate Distribution Frame (IDF). It's called horizontal cabling because it typically consists of the cables for a single floor, which run horizontally through wall ducts or ceiling spaces.
  • When using copper cabling, the IDF must be within 90 m (295 feet) of each wall port.
  • If this is not possible, multiple IDFs must be provisioned.
  • Multiple IDFs on the same floor are linked by horizontal cross-connects.

• Telecommunications Room: This is a room or closet that holds an Intermediate Distribution Frame (IDF) and other networking equipment, like switches. Essentially, this is a termination point for the horizontal cabling, where it connects to the backbone cabling. This room should only be used for networking equipment (not for general storage) and should ideally be secured with a lockable door.
• Backbone Cabling: This connects the Intermediate Distribution Frames (IDFs) to a Main Distribution Frame (MDF). It's also called vertical cabling because it is more likely to run up and down between floors.
• Entrance Facilities/Demarc: This is a special type of telecommunications room that marks the point where external cabling is joined to internal cabling, via the MDF.
  • Entrance facilities are needed to connect your network to the local exchange carrier's (LEC's) network and for communication between buildings
  • The demarcation point is the exact spot where the access provider's network ends and your organization's network begins.
• Smaller facilities might not require IDFs. If distance limitations are not exceeded, wall ports can be terminated directly to a single main distribution frame.

T568A and T568B Termination Standards

Twisted pair cables must be terminated correctly. Patch cords have RJ45 plugs on the ends , while structured cabling is terminated at insulation displacement connectors (IDCs) in wall ports and distribution frames. When you're connecting a cable, an organization should use a consistent wiring scheme across all sites.

• Each conductor in a 4-pair data cable is color-coded.
• Each pair is assigned a color (blue, orange, green, or brown).
• One wire in each pair has a mostly white insulator with a stripe of the color , while the other wire has a solid color insulator.
• The ANSI/TIA/EIA 568 standard defines two methods for terminating Ethernet cabling: T568A and T568B.

In T568A, the green pairs are wired to pins 1 and 2, and the orange pairs are wired to pins 3 and 6. In T568B, these pairs swap places, so orange is terminated to pins 1 and 2 and green to 3 and 6. Organizations should try to avoid using a mixture of the two standards. T568A is required by the residential cabling standard (TIA 570) , but T568B is probably the more widely deployed of the two.

Note: Cat 7 and Cat 8 cables are so sensitive to noise that the secondary wire in each pair is solid white with no stripe, as the coloring process reduces the effectiveness of the insulation.

Patch Panels

Cable management techniques and tools ensure that cabling is reliable and easy to maintain. Structured copper wiring runs from a wall port in the user's work area to some type of distribution frame in the network closet. At both ends, it is terminated at a punch down block with insulation-displacement connection (IDC) terminals. An IDC contains contacts that cut the insulation from a wire and hold it in place. This design allows large numbers of cables to be terminated within a small space.

In data networks, numerous moves, adds, and changes (MACs) would require re-terminating the wiring. To simplify MACs, a distribution frame is normally implemented as a patch panel.

• A patch panel has punch down blocks on one side and pre-terminated RJ45 modular ports on the other
• This allows incoming and outgoing connections to be reconfigured by changing the patch cable connections, which is much simpler than re-terminating punch down blocks.
• The structured cabling running from the work area or forming a backbone is terminated at the back of the patch panel on the IDCs, using either T568A or T568B wiring order.
• An RJ45 patch cord is used to connect the port to another network port, typically a switch port housed in the same rack.
• This greatly simplifies wiring connections and is the most commonly installed type of wiring distribution where connections need to be changed often.

Example of punch down blocks on the rear of a patch panel

Photo of the front of a patch panel

Structured Cable Installation

Installing structured cable from a bulk spool is referred to as pulling cable because the cable must be pulled, carefully, from the telecommunications closet to the work area. Cable is normally routed through conduits or wall spaces , avoiding excessive bends and proximity to electrical power cables and fittings, such as fluorescent lights, as these could cause interference.

• The main fixed cable run can be up to 90 m (295 feet).
• Stranded-wire patch cords can be up to 5 m each (16 feet) and no more than 10 m (33 feet) in overall length.
• This is because the attenuation of stranded cable is higher than solid cable. This means the signal gets weaker over distance, which is why stranded cables are only used for short patch cords.

Starting at the patch panel, you label the end of the cable with the appropriate jack ID, then run it through to the work area. This is also referred to as a drop, as in most cases you will be dropping the cable from the ceiling space through a wall cavity. If several cables are going to roughly the same place, you can bundle them and pull them together.

• Leave enough slack at both ends (a service loop) to make the connection and to accommodate future reconnections or changes, cut the cable, and label the other end with the appropriate ID.
• Electrician's scissors (snips) are designed for cutting copper wire and stripping insulation and cable jackets.
• Alternatively, there are dedicated cable stripper tools that have replaceable blades for different data cable types.
• Cable-cutting blades should be rounded to preserve the wire geometry.
• Stripping tools should have the correct diameter to score a cable jacket without damaging the insulated wires inside.

Termination Tools and Techniques

To terminate a cable, untwist the ends of the wire pairs and place them into the punch down block in the correct order for the wiring configuration (T568A or T568B) you want to use. It's very important not to untwist the wires too much. For example, Cat 6 cables are very sensitive and require no more than 0.375" (1 cm) of untwisting.

• Fixed cable is terminated using a punch down tool
  • This tool secures the conductors (wires) into an IDC.
  • There are different IDC formats (66, 110, BIX, and Krone), which require different blades.
  • Many punch down tools have replaceable blades.
  • The blades are double-sided: one side pushes the wire into the terminal while the other side cuts off the excess.
  • You must make sure the blade marked "cut" is oriented correctly to cut the excess wire.
• Alternatively, a block tool terminates a group of connectors in one action. For a 110 format panel, a four-position block is suitable for terminating 4-pair data cabling.

Typical punch down tool

A cable crimper is used to create a patch cord. This tool fixes a plug to a cable. The tools are specific to the type of connector and cable, though some may have modular dies to support a range of RJ-type plugs.

For shielded and screened cable, termination must be made to shielded IDCs or modular plugs.

• On an IDC, a metal clip placed over the exposed foil or braided shield bonds the cable to the housing.
• A shielded modular plug has a metal housing and is not terminated using a standard crimper.
• There are several different designs, but all follow the principle of connecting the cable shield to a bonding strip.

Typical cable crimper

Congratulations on making it through these notes! You've just taken a massive leap in understanding the foundational concepts of structured cabling. Remember, every expert was once a beginner, and by studying these topics, you're building a solid foundation for your networking career. Keep practicing, stay curious, and don't be afraid to get hands-on with the equipment. Good luck with your CompTIA N10-009 exam—you've got this!