Network+ Basics: Physical Installation

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.

Setting up a network isn't just about connecting cables. There are many important considerations when installing network equipment like switches, routers, wireless access points, and servers in a building. Things like power supply, temperature, humidity, and the risk of fire can all negatively affect how reliably your network services run. There are also security and access control factors to account for.

Even if you're not designing entire network sites right now, it's crucial to understand why these factors are important when you're doing maintenance or upgrading equipment.

As you study this lesson, here are some key questions to consider:

• How do rack systems ensure density and security?
• What considerations must be made for supplying power to run networking equipment?
• What are the risks from environmental factors, and how can they be controlled?

Rack Systems

It's important to install networking equipment in secure areas. Inside a building, these secure areas might be called telecommunications closets, equipment rooms, or server rooms. A whole building specifically set up to house many servers is called a Data Centre.

These spaces should only be used for installing network devices and servers, not for storing other random items. They need special physical security measures, like locked doors, so that only authorized people can get in.

Inside these telecommunications closets, server rooms, or datacenters, equipment is typically installed in structures called racks. A rack is a specially designed steel shelving system made for standard-sized equipment. Using a rack helps keep equipment more secure and takes up less space compared to just putting things on regular desks or shelves. This idea of fitting more computing devices into a smaller physical space is called density.

Network devices and servers made for racks are built to a standard size: 19 inches (about 48.26 cm) wide. Each device can be screwed directly into the rack. However, non-standard items, like a tower server (which stands upright like a desktop computer) or a monitor, can be placed on special shelves within the rack.

Image: Example of a server rack

If you don't plan to remove a device often for upgrades or maintenance, you can screw it directly into the rack. However, devices are often attached to special rail kits that let them slide out of the rack easily for hardware maintenance and upgrades, much like a drawer.

Understanding Rack Units (U)

Rack height is measured in units called “U", where one U equals 1.75 inches (about 4.45 cm). You can buy racks in different heights, typically from 8U (smaller) to 48U (very large). Equipment designed to fit in racks also specifies its height in 'U' units. This helps you plan exactly how much vertical space you'll need in your rack.

Most racks stand freely on the floor, but smaller ones that can be mounted on a wall are also available. You can bolt freestanding racks together in rows to create larger setups. There should be about 3 feet (1 meter) of clear space in an aisle in front of or behind the racks. This is important for technicians to access the equipment and for proper airflow

When you have multiple rows of racks, they should be placed back-to-back, not front-to-back. This setup helps maximize cooling efficiency. This arrangement is known as a “hot aisle/cold aisle" layout.

Rack-mounted devices usually have fans that pull in cool air from the front ("intake fans") and push out warm air from the back ("exhaust fans"). Some network switches can be set up in two ways for airflow: “port-side exhaust" (where hot air leaves from the same side as the network cables plug in) or "port-side intake" (where cool air comes in from that side). Using "port-side intake" lets you install a switch with its ports facing the front of the rack. This can sometimes be better for managing all the cables.

Example of utilizing hot and cold aisles

You should cover any unused spaces in the rack with side panels and "blanking plates" (special covers). This is important because it helps improve the airflow for the equipment. Each rack can also have lockable doors on the front and back. These doors prevent people who aren't authorized from accessing the equipment.

Humidity and Temperature

Controlling the environment (like temperature and humidity) helps prevent network downtime caused by equipment problems, such as devices overheating. Building control systems are designed to keep the environment in different parts of the building just right for equipment to operate efficiently. You'll often hear these systems referred to by the acronym HVAC, which stands for Heating, Ventilation, and Air Conditioning. HVAC systems use sensors to measure temperature and moisture (which tells them the humidity).

Servers and other network devices have their own built-in sensors inside their cases (the "chassis") to keep an eye on conditions. These sensors can report issues like too much heat inside the device, fan speeds, if a part breaks, or if someone tries to open the device ("chassis intrusion")—all of this goes to a central monitoring system.

Screenshot from HWMonitor Software showcasing CPU temperatures

Beyond individual devices, sensors can also be installed to measure the overall environmental conditions around a network rack, within a cabinet, or inside a server room or equipment closet. The following environmental factors need monitoring:

• Temperature: If it's too hot, the cooling systems in your devices and racks will struggle to get rid of heat effectively. This increases the chance that parts inside the device will overheat and cause problems.
• Humidity: Too much moisture (water vapor) in the air can lead to condensation forming inside a device. This can cause parts to rust (corrosion) or short circuits, which can damage the equipment. On the other hand, very low humidity can cause static electricity to build up, which can also damage electronic components.
• Electrical: Computer systems need a steady and reliable power supply. This means no power outages (complete power failures), no brief drops in voltage ("under-voltage events"), and no sudden increases in voltage ("spikes and surges"). Sensors built into power distribution systems (which manage electricity) and backup battery systems can report any issues or changes from a normal power supply.
• Flooding: There can be risks of flooding from natural sources like nearby rivers or lakes, or from human-made issues like leaky pipes or even fire suppression systems. If there's a significant amount of water, electrical systems must be shut down immediately to prevent damage or safety hazards.

Power Management
All types of network devices require a stable power supply to operate. Electrical problems, like sudden increases in voltage (spikes or surges), can cause computers, switches, and routers to crash. Similarly, a loss of power from brief voltage drops ("under-voltage events") or complete power failures will cause equipment to stop working. An "under-voltage event" is when the electrical voltage briefly drops, whereas a "power failure" is a complete loss of electricity that lasts for seconds or longer.

Power management involves setting up systems to protect your equipment from these electrical problems. The goal is to ensure network operations can either keep running without interruption or be restored very quickly after an issue.

Power Load and Voltage
The electrical circuits providing power to a rack, network closet, or server room must be able to handle the total amount of electricity (the "load capacity") needed by all the equipment installed there, plus some extra for future growth. Because of this, the AC (Alternating Current) electrical circuits in a server room are usually much stronger than those in a home or typical office. For example, they might be 30 or 60 amps, compared to a home's 13 amps. These circuits might also use a higher voltage (e.g., 240 VAC) instead of the lower voltage typically found in homes (e.g., 120 VAC).

Every piece of equipment has a power supply that tells you how much power it uses, measured in “watts". For example, a basic switch might use 20 watts, while a 1U server might use 200 watts. Wattage is calculated by multiplying Voltage (V) by Current (Amps). To figure out the maximum power a rack will draw, you add up the watts for all the devices and then divide that total by the circuit's voltage. For example, if a rack's equipment uses a total of 2,000 watts and the circuit voltage is 240 VAC, the current (amperage) would be 8.3 amps. So, a single 30-amp circuit could power three racks like that. However, if the circuits were 120 VAC (a lower voltage), the amperage needed would be double. This is why equipment rooms and datacenters often use higher voltage circuits – it's more efficient for power delivery.

Power Distribution Units (PDUs)
Each electrical circuit might be connected through a Power Distribution Unit (PDU). A PDU has special internal parts that "clean" the electrical power signal, protect against power spikes, surges, and drops in voltage, and can connect with an Uninterruptible Power Supply (UPS).

For smaller setups, PDUs are also available as "power strip" type units. These can handle more power than a regular home or office power strip (e.g., more than a typical 13-amp rated strip). These PDU power strips can be mounted horizontally or vertically in a rack, giving you flexibility for cabling and overall setup. Many PDUs also offer remote power monitoring. This means they can report how much power is being used, their current status, allow you to turn power to individual outlets on or off from a distance, or even turn outlets on in a specific order.

Battery Backups and Uninterruptible Power Supplies (UPS)
If the main power supply goes out, a battery backup system can keep your systems running for a few minutes to several hours, depending on how much power they need. Battery backup can be built into individual components, like a storage device's or storage array's cache memory, to protect data during a power loss. This battery protects any data that was being temporarily stored ("cached") or written when the power went out.

At a larger, system-wide level, an Uninterruptible Power Supply (UPS) provides a temporary power source when the main electricity fails. A UPS can keep devices powered on for anywhere from a few minutes (for a smaller desktop unit) to several hours (for a large enterprise system). Simply put, a UPS contains a bank of batteries, a circuit to charge them, and an "inverter" that converts the battery's DC (Direct Current) power into AC (Alternating Current) power that your devices can use. Different UPS models can provide varying amounts of power and come in different sizes and shapes, from small desktop units to large rack-mounted systems, depending on your specific needs.

Fire Suppression
Health and safety laws require organizations to have specific systems in place to detect and put out fires. Some basic fire safety measures include:

• Clearly marked fire exits and an emergency evacuation plan that is regularly tested and practiced.
• Building designs that prevent fire from spreading quickly, often by separating areas with fire-resistant walls and doors.
• Automatic smoke or fire detection systems, along with alarms that can also be set off manually.

Fire suppression systems are designed based on the "fire triangle" concept. The fire triangle illustrates that a fire needs three things to start and keep burning: heat, oxygen, and fuel. If you remove any one of these three elements, you can suppress (put out) or prevent a fire.

In the United States (and many other countries), fires are categorized into different "classes" by the NFPA (National Fire Protection Association) system. These classes are based on the type of material that is burning and fueling the fire. Portable fire extinguishers come in various types, and each type is specifically designed to fight a certain class of fire.

For example, "Class A" fire extinguishers are used for fires involving common flammable materials like wood, paper, cloth, and plastics. "Class C" extinguishers use a gas to put out fires and are specifically designed for electrical fires where water or other chemicals would pose a risk of electric shock. Buildings may also have an overhead sprinkler system installed. “Wet-pipe" sprinklers activate automatically when they detect heat and immediately release water. Wet-pipe systems always have water under high pressure in the pipes. This means there's a risk of burst pipes or accidental activation. Even in a real fire, the water discharge can cause significant damage to sensitive equipment.

However, there are several alternatives to wet-pipe systems that can help minimize water damage if they activate:

• Dry-pipe: These systems are used in places where freezing temperatures are possible. Water only fills this part of the system when sprinklers in another area are triggered by a fire.
• Pre-action: A "pre-action" system only fills with water after a fire alarm is triggered. It will then spray water only when the heat rises to a certain level at the sprinkler head. This offers protection against accidental water discharges and burst pipes, and also provides some time for people to try and put out the fire manually before the sprinklers activate.
• Halon:Gas-based systems like Halon have the advantage of not causing electrical short circuits and leaving no messy residue behind. In the past, Halon 1301 was commonly used in these systems. However, Halon is now banned in most countries because it depletes the ozone layer. Even so, many existing Halon systems haven't been replaced and are still allowed to operate legally.
• Clean Agent: Alternatives to Halon are called "clean agents". Besides not harming the environment, these gases are also considered non-toxic to humans. Examples include INERGEN (a mix of CO2, Argon, and Nitrogen gases), FM-200/HFC-227, and FE-13. These gases work in two ways: they reduce the amount of oxygen in the area (but not to levels that are dangerous for humans) and they also have a cooling effect on the fire. While CO2 (carbon dioxide) can also be used, it's not safe for use in areas where people are present because it displaces oxygen to dangerous levels.

Understanding the physical installation factors of networking equipment is a fundamental step in your journey into IT and networking. By paying attention to details like proper racking, environmental controls, power management, and fire suppression, you're not just setting up hardware – you're building a reliable, secure, and efficient foundation for your network infrastructure. As you continue your Network+ studies, remember that these practical considerations are just as crucial as the theoretical concepts. Keep exploring, keep learning, and you'll be well on your way to mastering the world of networking!