Network Devices – Functions, Significance and Security Practices

A network device is a piece of hardware or software integral to communication between a computer and an internet network. Network devices play two roles. The first is establishing a network connection, as a router or a modem does. The second one is maintaining, protecting and enhancing that connection, as with a hub, repeater, switch or gateway.

Functions of Network Devices

Network devices serve several key purposes:

  1. Facilitate Data Transmission: Devices enable seamless data transfer and communication between connected devices.
  2. Enable Secure Connectivity: They ensure efficient and secure network links, guarding against unauthorized access.
  3. Enhance Network Performance: Devices optimize traffic flow, enhancing overall network efficiency.
  4. Provide Network Security: Through access control and threat prevention mechanisms, they safeguard against malicious activities.
  5. Simplify Management: Devices aid in network configuration and management processes.
  6. Extend Coverage: They help overcome signal limitations and extend network reach.

Types of Networking Devices

Creating a network involves using many different types of network devices. Some are essential for establishing connections, while others enhance network performance. Here’s a list of network devices that contribute to secure information transfer within your organization:

In the 1990s, bridges, hubs, NICs, modems (for analog phone lines), and repeaters were the earliest network devices, found everywhere. In the early 2000s, DSL modems, leased line routers, WAPs, and firewalls became common. By around 2010, IDS and IPS with standalone functionality, along with VPN appliances, became the standard.


Enhancing network efficiency, a switch is a multiport device. It maintains limited routing information about nodes within the internal network, enabling connections to systems such as hubs or routers. Typically, switches link strands of LANs. Incoming packets’ hardware addresses are read by switches to efficiently transmit them to the intended destination.

Among switches, two major types exist:

  1. Modular switches: These accommodate system expansion as needed or based on changing network requirements.
  2. Fixed configuration switches: With a predetermined number of ports, these switches cannot be expanded. While more cost-effective, they offer less flexibility.

Switches can be either managed or unmanaged. Managed switches empower users to customize settings like LAN traffic and channel prioritization. Conversely, unmanaged switches are designed for basic connections and lack user-controlled settings.

Switches surpass hubs or routers in optimizing network efficiency due to their virtual circuit capability. Additionally, switches enhance network security since virtual circuits pose challenges for network monitors. Picture a switch as a device amalgamating the finest traits of routers and hubs. A switch operates within the data link or the OSI model’s network layer. A step further, multilayer switches operate at both layers, thus functioning as switches and routers. Notably, these high-performance devices support the same routing protocols as routers.

However, switches face vulnerability to distributed denial of service (DDoS) attacks. Flood guards act as shields, preventing malicious traffic from disrupting switches. Hence, safeguarding switches through port security is vital. This necessitates securing all switches by deactivating unused ports and employing dynamic host configuration protocol (DHCP) snooping, address resolution protocol (ARP), and Media Access Control (MAC) address filtering. These measures thwart unauthorized servers and IP addresses from infiltrating networks, ensuring only trusted ports transmit and receive data.


Bridges serve as connectors between two or more hosts or network segments. They accomplish this by storing or hosting frames between these segments. Hardware MAC addresses are utilized by bridges to transfer frames. They possess the capability to either forward or block data based on the MAC address of the devices linked to each segment. Additionally, bridges can unite two physical LANs into a larger, logical LAN.

Two models are employed to establish bridges:

  1. Local bridging: This form establishes LAN connections using local cables.
  2. Remote bridging: In this approach, two connections are brought together through a wide area network (WAN).

Although bridges share similarities with hubs, they exhibit distinct features. While both connect LAN components with similar protocols, bridges engage in filtering incoming data packets, termed frames, to discern addresses before forwarding. Remarkably, bridges neither alter the format nor the content of the incoming data during frame filtration. Instead, they meticulously filter and transmit frames within the network, assisted by a dynamic bridge table. The bridge table, initially empty, maintains LAN addresses for each computer within the LAN and the addresses of bridge interfaces connecting the LAN to other LANs. Bridges, much like hubs, come in the forms of simple or multiple-port configurations.

Recent times have witnessed a decline in the popularity of bridges, replaced by more versatile switches. Indeed, switches are sometimes coined “multiport bridges” due to their operational resemblance.


The primary role of a router is to steer network traffic. Routers ensure the smooth transfer of packets to their designated destinations by mapping a course through interconnected networking devices, utilizing various network topologies. These devices exhibit intelligence as they store data about their interconnected networks. Furthermore, the majority of routers double as packet-filtering firewalls, deploying access control lists (ACLs) for added security.

Working alongside a channel service unit/data service unit (CSU/DSU), routers also facilitate the translation from LAN framing to WAN framing. This adaptation is essential because LANs and WANs employ distinct network protocols. Such routers are termed border routers, positioned as the link connecting a LAN to a WAN’s external domain. Operating at the network’s border, they play a crucial role in ensuring seamless communication.

Routers are adept at segmenting internal networks into two or more subnetworks. Internally interconnected with other routers, they create zones that function autonomously. These devices maintain communication pathways by managing tables containing details about destinations and local connections. A router holds valuable information about the systems connected to it and knows where to direct requests when the destination is uncertain. Typically, routers use one of three standard protocols—Routing Information Protocol (RIP), Border Gateway Protocol (BGP), or Open Shortest Path First (OSPF)—to share routing and pertinent information.

Functioning as the frontline defense, routers assume the vital task of filtering network traffic. They must be configured to allow only authorized traffic sanctioned by network administrators. Configuration of routers occurs in either static or dynamic modes:

  • Static routers: These require manual configuration, maintaining settings until adjusted.
  • Dynamic routers: They leverage data about neighboring routers to construct dynamic routing tables.


A firewall functions as a gatekeeper for a private network, regulating the flow of internet traffic in and out. Its role involves scrutinizing and controlling data packets based on preset criteria, which could either be whitelists or blacklists. Whitelists exclusively permit data meeting specific parameters, while blacklists reject any data within those parameters.

In private networks, especially those handling sensitive information, firewalls are indispensable. Internally, they prevent access between distinct subgroups. For instance, they might restrict the sales department’s access to files related to IT or HR.

Diverse types of firewalls cater to varied needs, with the choice hinging on your specific operations. Some of the common firewall types encompass:

  1. Packet filtering: Serving as a network layer checkpoint, it assesses data packets by parameters like IP address, packet type, port number, or network protocols.
  2. Stateful inspection: Operating at network and transport layers, this analysis encompasses source IP, destination IP, source port, and destination port.
  3. Next-generation: This advanced variant delves into the actual content of packets, thoroughly examining TCP handshakes. It scans for malware and identifies intricate threats (refer to the section on IDS and IPS below).

While each firewall type offers benefits, packet filtering stands as the fundamental option. Stateful inspection elevates the defense mechanism. Meanwhile, next-generation firewall techniques boast the highest level of thoroughness and security, making them a preferred choice, especially in tightly regulated sectors like finance and healthcare.


Operating at the physical layer of the OSI model, a repeater is an electronic device designed to enhance a received signal. It captures a signal and subsequently amplifies it to a higher power or level. This amplification leads to extended signal coverage, occasionally spanning over 100 meters for conventional LAN cables.

Repeaters prove invaluable, particularly in expansive facilities where Wi-Fi coverage might be inconsistent in remote areas. Locations such as large office buildings, warehouses, laboratories, and campuses can all reap the advantages offered by repeaters.


Serving as vital connectors, gateways link networks operating on distinct protocols, enabling seamless data transfer between destinations. Typically functioning at the Transport and Session layers of the OSI model, these devices play a pivotal role. Above the Transport layer, a multitude of protocols and standards from various vendors coexist, and gateways play a crucial role in managing them.

Gateways excel in the translation between diverse networking technologies, such as Open System Interconnection (OSI) and Transmission Control Protocol/Internet Protocol (TCP/IP). This unique capability facilitates the connection of multiple autonomous networks, each equipped with its own routing algorithms, protocols, topology, domain name service, and network administration procedures and policies. Remarkably, gateways encompass all the functionalities of routers and more. In essence, a router enhanced with translation capabilities becomes a gateway.


Functioning solely at the Physical layer of the OSI model, hubs serve as connectors for multiple computer networking devices. Notably, hubs lack the capabilities for packet filtering or addressing functions. Their primary role involves broadcasting data packets to all devices interconnected. Moreover, a hub functions as a repeater, amplifying signals that tend to weaken after traversing lengthy distances through connecting cables. Operating as the most uncomplicated network connecting device, hubs establish connections among LAN components possessing identical protocols.

Hubs exhibit versatility in their ability to handle both digital and analog data, contingent on appropriate settings configured to accommodate incoming data formatting. For instance, if the data arrives in a digital format, the hub must relay it as discrete packets. Conversely, if the data takes on an analog form, the hub transmits it as a signal.

The hub category encompasses two distinct types:

  1. Simple hub: These possess a sole port designated for device connection to other networks.
  2. Multiple-port hubs: This variety permits users to link numerous devices, some even expand in a modular fashion.

Furthermore, active and passive hubs constitute hub variations. Active hubs amplify signals akin to repeaters, whereas passive hubs lack signal boosting capabilities.


A modem (modulator-demodulator) serves to convert digital signals into analog signals of varying frequencies, which are then transmitted to a receiving modem located elsewhere. Subsequently, the receiving modem executes the reverse transformation, yielding a digital output destined for a device linked to the modem, typically a computer. Facilitating this transfer, digital data commonly journeys to and from the modem through a serial line employing the industry-standard interface, RS-232.

Three primary modem types are prominent:

  1. DSL modem: This variant employs telephone cables and is acknowledged as the slower connection.
  2. Cable modem: Transferring data over TV lines, this type outpaces DSL in terms of speed.
  3. Wireless modem: Operating as the fastest transmitter, it facilitates information exchange between the local network and an internet service provider.

Network Interface Cards (NICs)

A network interface card, often referred to as NIC, stands as an internal hardware chip with the pivotal role of establishing connectivity between a device and the internet. Operating at the TCP/IP layer, the NIC fosters the connection of a device to a network. Functioning at the physical layer, the NIC emits a signal carrying information to the network layer. This trajectory encompasses the journey of all data as it traverses through the NIC, onwards to the server, and subsequently back to the originating device.

Two primary types of NICs are distinguished:

  1. Ethernet NIC: Featuring an 8P8C socket designed for the connection of an ethernet cable.
  2. Wi-Fi NIC: This variant interfaces with a wireless network.

It’s noteworthy that while mobile devices solely incorporate a wireless NIC, most computers incorporate both a Wi-Fi NIC and an Ethernet chip. While Ethernet ports offer heightened reliability, they somewhat limit a user’s mobility while handling the device.

Wireless Access Points (WAPs)

Wireless Access Points (WAPs) are devices that create wireless LANs (WLANs) through a transceiver, antenna, transmitter, and adapter. They link WLANs and wired ethernet LANs using a wireless infrastructure network mode, expanding network reach. Multiple WAPs might be needed for full coverage, and each has a transmission range based on wireless standards, obstacles, and environment. WAPs with high-powered antennas extend this range.

WAPs can offer extra ports for network expansion, firewall capabilities, and DHCP. Service Set Identifier (SSID) is vital for wireless network connection. WAPs can be “fat” or “thin,” with different configuration approaches.

Intrusion Detection and Prevention Systems (IDS and IPS)

IDS and IPS monitor networks for unauthorized access. IDS sends alerts, while IPS blocks intrusions. Both utilize signatures and anomalies for detection. There are host-based implementations for device protection.

Virtual Private Networks (VPNs)

VPNs securely connect endpoints via tunneling protocols, even over public networks. Remote access VPNs are common, especially with remote work. Understanding VPN basics is crucial for security professionals.

See Networking devices buying guide

Best Practices for Managing Network Device Security

Understanding network device types is essential for a reliable network, but ensuring security is equally crucial. To prevent connection and security issues, consider these best practices:

  1. Regular Updates: Keep devices updated with firmware and software patches to prevent vulnerabilities and maintain optimal performance.
  2. Harden Configurations: Adjust default settings to industry standards, reducing the risk of unauthorized access to the network.
  3. User Management: Enforce strict user access controls, replacing permanent privileged accounts with just-in-time access.
  4. Network Segmentation: Create subnetworks and VLANs to protect sensitive data and limit access to authorized devices.
  5. Anomaly Monitoring: Monitor network activity for unusual patterns or behaviors, maintaining vigilant security.
  6. Periodic Assessments: Conduct regular security audits to identify vulnerabilities and apply necessary fixes.
  7. Constant Vigilance: Recognize that security is an ongoing process, requiring continuous monitoring and improvement.

In conclusion, assembling the appropriate network devices enables the creation of a secure organizational network. By diligently overseeing network device activity, you can promptly detect potential attacks and ensure the ongoing security and availability of your network.

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