In a Local Area Network (LAN), a network hub acts as a central hub, enabling communication between multiple devices and connecting them in a single network segment.
What Is a Network Hub?
A network hub is a basic networking device that connects multiple Ethernet devices, making them act as a single network segment. Hubs work at the physical layer (layer 1) of the OSI model and transmit data packets to all connected devices, regardless of the intended recipient. They receive data packets (bits) from one device and broadcast them to all other connected devices without data packet filtering or routing.
Hubs do not manage any traffic coming through them; they simply replicate the data they receive across all connected ports. This can lead to collisions and network inefficiency in busy networks because only one device can communicate at a time. Consequently, hubs are generally considered less sophisticated and efficient compared to switches, which can direct data intelligently to specific devices on the network based on their addresses.
Network hubs are generally considered outdated technology for many network environments because they operate inefficiently, especially as network size and traffic grow. The use of hubs has largely been superseded by more advanced networking devices like switches and routers in most networking environments.
Network Hub Features
Here are some key features of network hubs:
- Simplicity. Hubs are simple devices with no software configuration.
- Broadcast traffic. They broadcast incoming packets to all ports.
- Single collision domain. All ports on a hub share the same collision domain.
- Single broadcast domain. Similarly, all ports share the same broadcast domain.
How Does a Network Hub Work?
Upon receiving a data packet from one connected device, the hub broadcasts this packet to every device connected to it, regardless of the intended recipient. This process is inherently simple, reflecting the hub's basic nature. The recipient device accepts the packet while all others disregard it based on its destination address.
Because all data is sent to all devices, and only one device can send data at a time, network hubs can create large collision domains. A collision occurs when two devices send data at the same time, and the signals interfere with each other. The hub does not have the ability to manage or avoid these collisions.
Hubs do not process or filter data by MAC addresses or IP addresses, unlike switches and routers. They do not have the capability to determine the source or destination of the data, meaning they cannot direct traffic efficiently and can contribute to network congestion.
Network Hub Types
Network hubs are classified into three types:
- Passive hub. A passive hub is the simplest and least expensive type of hub. It acts like an electrical extension cord, broadcasting any data packet it receives on all its ports. Passive hubs do not regenerate or amplify the signal, so the quality of the signal can deteriorate as it passes through the hub. Additionally, passive hubs cannot filter data packets, so all devices connected to the hub will see all traffic, even if it is not addressed to them.
- Active hub. An active hub is more intelligent than a passive hub. It can regenerate and amplify the signal, improving the signal quality over longer distances. Active hubs can also detect collisions, which occur when two devices try to transmit data on the network simultaneously. When an active hub detects a collision, it can resend the data packets involved.
- Intelligent hub. An intelligent hub is the most advanced type of hub. It can perform all the functions of an active hub, plus it can also filter data packets. This filtering ability means that intelligent hubs improve network security by only sending data packets to the devices that are addressed to them. Intelligent hubs can also segment a network into smaller parts, which can help improve network performance.
Network Hub Advantages and Disadvantages
While network hubs have been largely superseded by more advanced technology in many networking scenarios, they still offer unique advantages. However, these benefits come alongside notable disadvantages, primarily due to the hub's simplistic design and operation mode.
Advantages
These are the advantages of using a network hub:
- Cost-effectiveness. Hubs are generally cheaper than switches and routers.
- Ease of installation. With no configuration needed, hubs are straightforward to set up.
- Ideal for small networks. Hubs can suffice for basic connectivity needs for small, simple networks.
Disadvantages
Here are the drawbacks of network hubs:
- Lack of efficiency. Broadcasting to all devices leads to network inefficiencies.
- Security concerns. Since all data is broadcasted, sensitive information might be exposed to all devices on the network.
- Collisions. The shared collision domain can lead to data packet collisions, affecting network performance.
