Image Credit: Allied Electronics and Miles Tek Corporation
Network hubs provide a central location for attaching wires to workstations. Often, these hardware devices include a network switch that controls how and where data is forwarded.
How Hubs Work
Hubs receive data, but do not provide redirection or filtering. Although some can regenerate and retime signals, they cannot determine the best path. In the Open Systems Interconnection (OSI) model, network hubs operate at the physical layer (layer 1).
This diagram depicts the role of a USB hub in a network.
Image Credit: Broadband Buyer
Types of Network Hubs
There are three types of network hubs: passive, active, and intelligent.
- Passive hubs or concentrators do not amplify or regenerate incoming signals before rebroadcasting them to the network. They do not improve the performance of local area networks (LANs), and may limit maximum media distances. Typically, passive hubs are connected to other devices in a star configuration.
- Active hubs or multiport repeaters amplify the incoming electrical signals that contain data packets. They maximize network media distances and follow the same rules as repeaters. Although active hubs do not prioritize data packets, they can be configured as firewalls to examine them. If a received signal is too weak for rebroadcasting, active network hubs apply retiming and resynchronization techniques.
- Intelligent hubs work like active hubs and include remote management capabilities. They also provide flexible data rates to network devices.
Product and Performance Specifications
The GlobalSpec SpecSearch database allows industrial buyers to specify network hubs according to voice and data protocols (e.g., Ethernet, CANbus). When selecting products, buyers should specify both the number of ports and the port type (e.g., RJ-45, USB). Speed is another important consideration.
Features and Applications
Some Ethernet hubs are PoE ready, meaning that they provide power over Ethernet capabilities (PoE). Although some network equipment is designed for use in computer rooms, other devices are hardened to withstand extreme conditions. In terms of applications, network hubs may be used to connect computers to servers, printers, and other computers.
Related Products & Services
Network equipment is used to split, switch, boost, or direct packets of information along a network. This product area includes network hubs, switches, routers, bridges, gateways, multiplexers, transceivers and firewalls. In addition to device type, network equipment is defined by protocol (e.g., Ethernet).
Network firewalls protect computer networks against unauthorized use or attack. They permit or deny access to private network devices and applications, and represent an important part of an organization's overall security policy. Firewalls may be software applications, hardware devices (such as routers), or a combination of both. They include turnkey products that are relatively easy to install as well as complex, multi-layer installations that require the expertise of a certified network administrator.
Network Repeaters and Extenders
Networking repeaters regenerate incoming electrical, wireless, or optical signals to preserve signal integrity and extend the distance over which data can travel. They are often used to connect cable segments in IEEE 802.3 networks.
Network routers are protocol-dependent devices that connect subnetworks, or that break down a large network into smaller subnetworks.
Network switches connect network devices to host computers and allow a large number of devices to share a limited number of ports. They increase network capacity and speed by examining and filtering data packets. Switches also regenerate forwarded packets, reducing collision rates and permitting the use of additional nodes.
Network transceivers connect nodes and send and receive signals. In Ethernet networks, they are called medium access units (MAU).
VoIP and IP Telephony
VoIP and IP telephony allows PC users to make phone calls over the Internet or other packet networks via gateways and standard telephones.