Difference between Switches and Hubs

This article addresses the problem faced by many people differentiating a network switch and a network hub. Switches and hubs have some similarities which maybe a little bit confusing. When you compare a physical switch with a hub, they look the same. The main difference between a network switch and a network hub is mainly on some extra duties performed by the switch.

Network Hubs

I will start with a hub then move on to talk about a switch highlighting the similarities and differences of the two devices.

• A hub operates at the Physical Layer (Layer 1), of the OSI reference model. It is mostly used in a star topology where all nodes are connected to a hub through a single cable.
• In a hub all packets transmissions that come into a physical port are rebroadcast to all connections. That means that if one device sends a network packet, all the other devices will receive it.
• All devices connected to a hub are said to be in the same collision domain.
• There are several types of hubs, namely: passive hubs, active hubs, switching hubs and intelligent hubs.

Network Switches

Switches on the other hand:

• Operate in the Data Link Layer (layer 2) of the OSI reference model.
• Like hubs, devices connected by a switch reside in the same collision domain.
• There are two types of switches, namely: Cut-through switch and a Store-and-Forward switch.

Comparing a network switch with a hub

• One of the differences between a switch and hub is that, a switch can filter and forward packets between LAN segments. It can therefore make a direct connection between the transmitting node and the receiving node unlike a hub which rebroadcasts signals out to all nodes connected to it beside the one in which it received the packet from.
• The main advantage of a switch over a hub is that it does not waste bandwidth by sending packets to nodes that are not intended to receive it. Each pair of nodes(sender and receiver) has a full bandwidth of the network dedicated to it when communication through a switch. For example, for a standard Ethernet LAN, when using a hub, say with 20 computers, all the 20 computers have to share the same 10 Mbps of bandwidth. By replacing a hub with a switch, each pair of nodes has its own dedicated 10 Mbps stream. This improves the overall performance of the network without any further modifications.
  
• A hub is mostly suitable for small networks. For much larger networks a switch will perform better than a hub. Switches are usually a little more expensive than hubs.

So deciding which one of the two to use will depend on several factors such as the size of the network, type of network and of course, how deep your pockets are. By compromising on the bandwidth utilization you can use a hub which is a little bit cheaper or if you want a much better network performance and optimal bandwidth usage a network hub is the way to go; moreso it is much more intelligent than a hub.

I hope this article clarifies the dilemma people usually have when deciding on the differences between a hub and a switch to be able to answer N+ exam questions like,

• Which of the following operates at the physical layer? A. Hub, B.Switches, C. Wireless Access Points D. Routers
• At which layer of the OSI reference model does a hub [or switch] operate?