Hubs

A special type of network device called the hub can be found in many home and small business networks. Though they've existed for many years, the popularity of hubs has exploded recently, especially among people relatively new to networking.

General Characteristics of Hubs

A hub is a small rectangular box, often made of plastic, that receives its power from an ordinary wall outlet. A hub joins multiple computers (or other network devices) together to form a single network segment. On this network segment, all computers can communicate directly with each other. Ethernet hubs are by far the most common type, but hubs for other types of networks such as USB also exist.

A hub includes a series of ports that each accept a network cable. Small hubs network four computers. They contain four or sometimes five ports, the fifth port being reserved for "uplink" connections to another hub or similar device. Larger hubs contain eight, 12, 16, and even 24 ports.

Key Features of Hubs

Hubs classify as Layer 1 devices in the OSI model. At the physical layer, hubs can support little in the way of sophisticated networking. Hubs do not read any of the data passing through them and are not aware of their source or destination. Essentially, a hub simply receives incoming packets, possibly amplifies the electrical signal, and broadcasts these packets out to all devices on the network - including the one that originally sent the packet!

Technically speaking, three different types of hubs exist:

• passive
• active
• intelligent

Passive hubs do not amplify the electrical signal of incoming packets before broadcasting them out to the network. Active hubs, on the other hand, do perform this amplification, as does a different type of dedicated network device called a repeater. Some people use the terms concentrator when referring to a passive hub and multiport repeater when referring to an active hub.

Intelligent hubs add extra features to an active hub that are of particular importance to businesses. An intelligent hub typically is stackable (built in such a way that multiple units can be placed one on top of the other to conserve space). It also typically includes remote management capabilities via SNMP and virtual LAN (VLAN) support.

Hubs remain a very popular device for small networks because of their low cost. A good five-port Ethernet hub can be purchased for less than $30 USD. USB hubs cost only a bit more.

Which Hub Is Right For You?

For many home networks, a four-port hub is sufficient to build a simple LAN

The least expensive four-port hubs support 10 Mbps Ethernet. 10 Mbps will support basic sharing of either traditional dial-up, cable modem, and DSL Internet service.

So-called 10/100 hubs support both 10 Mbps (traditional Ethernet) and 100 Mbps (Fast Ethernet) connections. These higher-performance hubs can prove very useful in some situations. For example, online gamers who enjoy "LAN parties" and home multiplayer gaming will almost certainly notice a significant performance increase when running at 100 Mbps. Note that to network at this speed, both the hub and the network interface card (NIC) on the computer must be rated at either 10/100 Mbps or 100 Mbps.

When acquiring a hub, many people fail to consider the noise a hub can generate. Older hubs contain fans used to keep the unit cool, and the noise from these fans ranges from barely perceptible to quite annoying depending on the quality of the manufacturing. The situation has improved in recent years: hubs used to sound something like a jet engine when powered on in a quiet room. Nowadays, manufacturers have successfully eliminated the need for a fan in their hubs, and most models are effectively silent.

Conclusion

Hubs offer a convenient, affordable way to build a home or small business network. Several manufacturers produce hubs in varying port configurations, but even the most basic hubs can provide satisfactory file sharing and Internet connection sharing for a small LAN. Hubs work with traditional dial-up or broadband Internet service. For high-performance applications such as online gaming and frequent sharing of large files, networkers will want a more expensive 10/100 Fast Ethernet-capable hub. Future high-speed Internet services like VDSL will almost certainly require Fast Ethernet performance as well.

Hubs provide just one way to implement internetworking on a LAN. Alternatives to hubs including switches and routers generally offer more features, higher performance, and a higher price tag.

Makes Available For Hubs