CompTIA A+ Core Certification: A Simple Guide To Networking - Networking Hardware

220-1101: Objective 2.2: Compare and contrast common networking hardware.
Understanding how computers communicate on a network is essential for any IT professional. Network environments can range from simple home networks to complex corporate designs, but certain essential elements and functions apply to all networks. The following sections cover basic networking hardware devices used to build small networks and describe how they contribute to the communication process.

Router
A router connects one network to another. For example, a router connected to a cable modem or DSL modem enables multiple devices on a LAN to share a single broadband connection to the Web.
Most routers sold for SOHO configurations are Wi-Fi (802.11 family) wireless routers with integrated Fast Ethernet or Gigabit Ethernet switches. Both wired and wireless devices can be on the same network and can share folders and printers, as well as Internet access.
shows the rear of a typical 802.11ac router for cable Internet from ASUS.



Many Wireless Routers Can Now Be Used as Hosts for USB Drives for Shared Network Storage

A router used for DSL is similar in appearance to a router used for cable Internet, but it features a DSL port. The switches built into routers are also stackable. If a router needs more ports, you can add a switch.
Routers are specialized computing devices that are controlled by firmware. When you log into a router to view or change its configuration, the router’s firmware limits the options available. Buggy firmware can cause network problems and make a network more vulnerable to attack.
Use a router’s configuration program to determine the firmware date and version it uses. If the router is using an older version of firmware, check the vendor’s website for an update. Before downloading the update, read the technical notes to see what issues the firmware affects and whether the update might cause any other problems. Download the update and follow the vendor’s instructions for installing the firmware.
If you want more features than the vendor-provided firmware includes, check for third-party firmware. DD-WRT is Linux-based, alternative open source firmware that is suitable for a great variety of WLAN routers and embedded systems. DD-WRT is the most popular replacement firmware for routers, and some vendors now use it in their high-end routers.

Switch
A switch provides connectivity to devices in a local network. Each port on a switch works independently, allowing more than one concurrent session. A switch makes a direct connection between the sending and receiving devices by identifying the Media Access Control (MAC) address of each device. In today’s networks, switches are common in 100Mbps, 1000Mbps, 10Gbps, and even 40Gbps networks. Switches can be stacked to increase the number of connection ports in a network. Stacked switches are daisy-chained together and, in theory, no limit governs the number of switches possible in a network.

A switch resembles a hub but creates a dedicated full-speed connection between the two computers that are communicating with each other. A five-port 10/100/1000 switch, for example, provides the full 100Mbps bandwidth to each port connected to a Fast Ethernet or 10/100 card. If the network adapters are configured to run in full-duplex mode (that is, to send and receive data simultaneously) and the switch supports full-duplex mode (as most modern switches do), the bandwidth is doubled; for example, Fast Ethernet bandwidth (100Mbps) on the network would be doubled to 200Mbps, and Gigabit Ethernet (1000Mbps) bandwidth would be doubled to 2Gbps. Low-cost switches used in small office/home office (SOHO) networks (see Figure) cannot be configured to perform complex switching functions and are considered unmanaged. Managed switches, which are common in corporate and enterprise networks, also support SNMP for diagnostics and performance measurement, virtual LANs (VLANs) to enable multiple workgroups to use the same physical switch but keep their traffic separate, and redundancy.



An Unmanaged Fast Ethernet (10/100) Five-Port Switch

Wireless Access Point
Whereas hubs and switches deal with wired networks, a wireless access point (WAP) extends a wired network to wireless connections. It is also based on Ethernet, but it involves the IEEE 802.11 group of standards, which define wireless LANs (WLANs). A WAP acts as a central connecting point for computers equipped with wireless network adapters; similar to a switch, a WAP identifies each computer by its MAC address.

To turn a wireless router into a WAP (which then needs to connect to a separate router), check the configuration options available for the router.

Patch Panel
A patch panel is a box designed as a junction point for twisted pair (TP) cable and fiber cable used in networks. Patch panels are typically built into wiring closets or added to equipment racks in a 1U or taller form factor.
After any connector on the cable is removed, each wire in the TP cable must be untwisted before it is punched into the appropriate connection on the back of the panel. The twisted cables are color coded so that they can be properly terminated at the other end. The most common standards for color coding are known as T568A and T568B. Be sure to use the color coding that matches the rest of your network. 
The front of the patch panel uses RJ-45 connectors for short standard network cables.

Firewall
A firewall is a hardware appliance or software application that protects a computer from unwanted intrusion. The networking world is especially concerned with hardware-based devices that protect an entire group of computers, such as a LAN. With small offices and home offices, firewall functionality is usually built into the router. In larger organizations, the firewall is a separate device. A firewall stops unwanted connections from the outside and can block basic network attacks.

Power over Ethernet
A Power over Ethernet (PoE) switch has added capability (a built-in endspan) to send power out a port using Cat 5 or better grades of twisted pair cable. The switch can send up to 25.5 watts of power on the unused twisted pairs (pins 4–5 and 7–8) in 10Base-T or 100Base-T Ethernet (PoE Mode B) or by using all four wire pairs (PoE Mode A), enabling it to be used with Gigabit Ethernet. PoE enables wireless access points, IP security cameras, VoIP phones, routers, and other Ethernet devices to be installed in areas away from traditional power sources.
A PoE switch endspan is built into a switch. Another type of PoE device, known as a power over Ethernet injector, is installed between a standard Ethernet switch and a PoE device to provide power only.
 

The original PoE standard, IEEE 802.3af, was introduced in 2003. It provides up to 15.4 Watts (W) of power to a PoE device; however, only 12.95W is guaranteed because of power dissipation in the cable. In 2009, IEEE 802.3at Type 2 was introduced and improved upon the previous standard. This update provides up to 30W of power, but only 25.5W is guaranteed. Up to this point, the power provided was sufficient enough to power devices such as VoIP phones, security cameras, alarm systems, and wireless access points. In 2018, IEEE 802.3bt was created to help meet the demand for more power capacity. It introduced two new types: Type 3 and Type 4. Type 3 provides up to 60W of power, for devices such as videoconferencing equipment and multi-radio wireless access points. Type 4 provides up to 100W and can support devices such as flatscreen displays or laptops.

This table compares the four different PoE standards.

Table: PoE Standards

Hub
A hub is the simplest device used on an Ethernet network for connecting devices to each other. As networks have become more complex, simple hubs have become rare. A hub features multiple RJ-45 ports, a power supply, and signal lights to indicate network activity. Hubs have been used to connect computers and to boost the communication signal between computers.

Switches have almost completely replaced hubs because a hub splits the bandwidth of a connection among all the computers connected to it. For example, a five-port 10/100/1000 Ethernet hub divides the 1000Mbps speed of Fast Ethernet among the five ports, providing only 200Mbps of bandwidth to each port for Fast Ethernet and 10/100/1000 adapters. A hub also broadcasts data to all computers connected to it.

Modems: Cable and DSL
A modem connects a LAN to an Internet service provider (ISP). The term modem (short for modulator/demodulator) was originally used only for analog (dial-up) modems when most computer networks were connected by phone systems.
Today the term modem is typically applied to any device that connects to the Internet. Cable modems and DSL modems, the devices most commonly used to connect small networks to the Internet, are referred to as modems even though they work quite differently than dial-up modems. 

Optical Network Terminal (ONT)
As fiber becomes more affordable as a connection option, its use among end users is growing. An optical network terminal (ONT) is similar to a modem, in that it connects the end user to the ISP, but because the communication is light pulses instead of electrical signals, no modulating/demodulating takes place. Thus, an ONT is technically different than a modem.

Network Interface Card
A network interface card (NIC) is the interface on a computer (or other device) that connects to the LAN. A NIC was traditionally a circuit board (card) that mounted to the motherboard, but now NICs are built-in interfaces. A NIC connects to a cable with an RJ-45 connecter. The NIC is designed to take communication off the physical cable (or wireless signal from the air) and present it to the computer for processing. A NIC has a unique physical address, known as a MAC address, that identifies the device to other hosts on the network. NICs have evolved to also provide wireless and virtual access to networks.

Software-Defined Networking
As you have learned so far, computer networks are made up of devices that are connected together and configured by people to enable communication. Over time, the technical capabilities of networking devices have grown in scope, so it is no longer practical to have human interaction to manage every device and configuration on large enterprise networks.

A software-defined network (SDN) is a network in which a virtual layer created in software controls the data flow over the physical network devices. SDN uses traditional networking devices, such as a router and switches, and breaks down the process of how these devices operate into two planes, called the data plane and the control plane. The data plane is in charge of sending, receiving, processing, and forwarding data. The control plane controls how the data plane operates. It tells the data plane how networking packets are to be sent and received. In addition, an SDN controller allows administrators to make changes to the control plane and manage how data is processed and forwarded. SDN takes the control plane function out of networking devices; instead, an SDN controller manages that plane for the devices. SDN is changing the world of networking and how administrators manage devices and data flow on the network.