Supporting Cabling and Physical Installation

April 01, 2025

Supporting Cabling and Physical Installation

Network Data Transmission

• Network data transfer works by modulating the properties of a transmission medium, electric current, infrared light, or radio waves to encode a signal

• Each media type supports a range of possible frequencies. Higher frequencies allow for more data to be transferred per second. The range of frequencies is referred to as the media bandwidth.

Ethernet Standards

• The institue of electrical and Electronics Engineers (IEEE) sets the standards
• 802.3 Ethernet standards are very widely used on both LANs and WANs
• Ethernet standards provide assurance that network cabling will meet the bandwidth requirements of applications.
• The ethernet media specifications are named using a three-part convention, which is often referred to as xBASE-y.
  • The speed or bit rate in megabits per second (MBPS) or gigabits per second
  • The signal mode (baseband or broadband). all mainstream types of Ethernet use baseband transmissions, so you will only see specifications of the form xBASE-y
  • A designator for the media type

Media Access Control and Collision Domains

Media access control (MAC) refers to the methods a network technology uses to determine when nodes can communicate on shared media and to deal with possible problems, such as two devices attempting to communicate simultaneously.

Collision domains:

A collision domain is, as the name implies, the part of a network where packet collisions can occur. A collision occurs when two devices send a packet at the same time on the shared network segment. https://study-ccna.com/collision-broadcast-domain/

The ethernet protocol governing contention and media access is called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). A collision is the state when a signal is present on an interface’s transmit and receives lines simultaneously. On detecting a collision, the node broadcasts a jam signal. Each node that was attempting to use the media then waits for a random period before attempting to transmit again.

The collision detection mechanism means that only half-duplex transmission is possible.

100BASE-TX Fast Ethernet Standards

The fast Ethernet standard uses the same CSMA/CD protocol as 10BASE-T but with higher frequency signaling an improved encoding methods, raising the bit rate from 10 Mbps to 100 Mbps. 100BASE-TX refers to fast ethernet working over Cat5 twisted pair copper cable with a maximum supported link length of 100 meters.

Gigabit Ethernet Standards

Gigabit Ethernet builds on the standards defined for Ethernet and fast Ethernet to implement rates of 1000 Mbps (1Gbps), when installed using Cat5e or better copper wire. Gigabit Ethernet is specified as 1000BASE-T. Gigabit Ethernet doesn’t support hubs; it is implemented only using switches. The maximum distance of 100 meters applies to cabling between the node and the switch port, or between two switch port.

Gigabit is supported by both copper cable and fiber, while copper wire can be cost effective and the fiber cable can be expensive.

10 Gigabit Ether (10GbE) multiplies the nominal speed of Gigabit Ethernet by a factor of 10. Because of the higher frequencies required, 10 GbE can only run at reduced distances over unshielded copper cables. For longer runs higher categories of copper wire with some type of shielding, or a fiber cable is required.

Specifications for 40 Gbps operation

Specification	Cable	Maximum Distance
10 BASE-T	UTP (Cat6)	55m (180 feet)
	F/UTP (Cat6A)	100m (328 feet)
	S/FTP(Cat7)	100m9328 feet)
40 GBASE-T	S/FTP (Cat 8)	30m 9100 feet)

note: 10/40 GBASE are mostly used to connect between appliances in a datacenter.

Fiber Ethernet Standards

Fiber optic cable uses infrared light signals, lights are not susceptible to the interfaces or noise from other sources such as copper cables. Fiber cables supports higher bandwidth over longer distance than copper wires. Fiber cables are divided into two category Single Mode fiber (SMF) and Multimode fiber(MMF). MMF is categorized by optical mode designations(OM1, OM2, OM3 and OM4).

Copper Cables and connectors

• Unshielded twisted pair
• have 4 pairs of wire twisted and covered with the outer jacket for protection.
• mostly suitable for 5 m distance

Shielded and screened Twisted pair cable

• these cables are less susceptible to interference and crosstalk
• these type of cables are required for some Ethernet standards and also can be required in certian types of environment where the interference is higher such as near fluorescent lighting, near motors, generators.

Shielded cable can be referred to generically as shielded twisted pair(STP), there are several types of shielding:

• Screened cable has on thin outer foil shield around all pairs. Screened cable is usually designated as screened twisted pair (ScTP )or foiled/unshielded twisted pair (F/UTP) of just foiled twisted pair (FTP)
• Fully shielded cabling has a braided out screen and foil-shielded pairs and is referred to as shielded/foiled twisted pari (S/FTP). There are also variants with a foil outer shield(F/FTP).
• U/FTP cable has foil-shielded pairs but no outer shield.

Legacy STP cable could be complex to install, as it required bonding each element to ground manually, but modern F/UTP and S/FTP solutions with appropriate cable, connectors, and patch panels reduce this complexity by incorporating bonding within the design of each element.

Plenum and Riser-rated Cable

Plenum cable:

• Plenum space is a void in a building designed to carry heating, ventilation and air conditioning (HVAC) systems.
• plenum space is used for airflow hence can be heated, these spaces are like false celling or as a raised floor
• Plenum-rated cable uses treated PVC or fluorinated ethylene propylene, making the cable less flexible but no impact on the bandwidth
• Plenum rated cable are marked CMP. General purpose cables are marked CMG or CM
• The cabling that passes between two floors is referred to as riser, the conduit for riser cabling must be fire stopped. This means that fire cannot spread through the opening created by the conduit. Riser cabling should also comply to the appropriate fire safety standards but are not quite strict as plenum spaces. The riser rated under NEC is marked CMR.

Coaxial and Twinaxial cable and connectors

Coaxial cable is made of two conductors that share the same axis. The core conductor is made of solid or stranded copper wire and is enclosed by plastic insulation. A wire mesh wrapped around the plastic constitutes the second conductor. This servers as shielding from interference.

• Coax cables are categorized using Radio Grade (RG) designations, representing the thickness of the core conductor and the cable’s characteristic impedance.
• RG6 is 18 AWG cable with 75 ohm impedance typically used as drop cable for cable Access TV and broadband cable modems.
• Thinner more flexible RG59 cable is used for audio/video and closed-circuit television(CCTV)

Connectors:

BNC BNC connectors are the connectors that uses a twist-and-lock mechanism

F-connector: While f-connector is secured by screwing them into place.

Twinaxial: is similar to coax but contains two inner conductors

• is used for datacenter interconnects working at 10 GbE and 40 GbE
• The maximum distance it covers is 5 meters for passive cable and 10 meters for active cable types
• Twinax for 10/40 GbE is terminated using Direct Attach Copper(DAC) transceivers

Structured Cabling System

• Structured cabling scheme is a standard way of provisioning cabled networking for computers in an office building.
• The best known is the ANSI/TIA/EIA 568 commercial Building Telecommunications wiring standard.
• ANSI/TIA/EIA identifies the following location or subsystems within a structured cabling systems:
  • Work Area: The space where user equipment is located and connected to the network, usually via a patch cable plugged into a wall port.
  • Horizontal cabling: Connects user work areas to an intermediate distribution frame (IDF). horizontal cabling connects through wall ducts or ceiling spaces and runs horizontally. IDF must be within 90 m cabling distance 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: intermediate distribution frame. This is a termination point for the horizontal cabling along with the connection to backbone cabling. This room must be used for networking equipment only and not general storage.
  • Backbone Cabling: Connects IDFs to a main distribution frame(MDF). Backbone cabling is also referred to as vertical cabling, as it is more likely to run up and down between floors.
  • Entrance Facilities/Demarc: special type of telecommunications room marking the point at with the external cabling is joined to internal cabling, via the MDF. Entrance facilities are required to join the local exchange carrier’s (LEC’) network and for inter-building communications. The demarcation point is where the access provider’s network terminates and the organization’s network begins.

T568A and T56B Termination Standards

• Twisted pair must be properly terminated
• Patch cords are terminated with RJ45 plugs, while structured cabling is terminated to insulation displacement connectors (IDCs) in wall ports and distribution frames.

T568A:

• green pairs are wired to pins 1 and 2, and the orange pairs are wired to pins 3 and 6.

T568B:

• orange pairs are connected to pins 1 and 2, and the green pairs are connected to 3 and 6 pins.

Patch Panels

• cable management techniques and tools ensure that cabling is reliable and easy to maintain
• The network cables from distribution frame and to the user’s work area terminates at punch down block with insulation-displacement connection (IDC) terminals
• The 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
• 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 T568A or T568B standard.
• The RJ45 is used to connect to the port to another network port, typically a switch port housed in the same rack

Reference: Comptia Network Plus (certmaster)