Difference Between Hub and Layer 2 Switch

Hub vs Layer 2 Switch

Hubs and switches are devices that we use to interconnect our computers in LANs. The main difference between a hub and a layer 2 switch is their complexity. A hub is a very simple device that does virtually no processing and simply forwards the packets it receives. It does not read or inspect the data contained in the packets. On the other hand, a layer 2 switch has the processing power to look at the packets to know the destination and the source. It stores and uses this information to determine where to send the packets.

The hub doesn’t need that information as once it receives a packet, it would simply broadcast or flood that packet to all other clients connected into the hub. It is up to the receiver to determine if the packet is meant for it or not. A layer 2 switch also does this but only when it does not have an entry for the destination. When the packet is received, a response is often created and the layer 2 switch will be able to extract the destination from the response packet and store it. From then on, flooding no longer occurs.

The downside to flooding is the massive performance hit experienced as you increase the number of clients in the network. With a hub, only a single client is able to transmit at a time and the bandwidth will be cut down by the number of clients attempting to transmit. This is similar to what happens in ham radio where other people need to wait for one to finish talking before they can talk. A layer 2 switch is able to employ micro-segmentation because it knows the destination and source of the information. This practically isolates the pair giving them maximum bandwidth regardless of what the others are doing. This is comparable to cellular phones since you can continuously talk with one person regardless of how many other people are on the channel.

Lastly, hubs are virtually obsolete and are no longer being produced or marketed. The cost of processing power has dropped significantly that the price difference between a hub and a layer 2 switch would be negligible. But because the two look identical on the outside, people still commonly refer to switches as hubs; thus leading to confusion.

Summary:

1. A hub is a simpler device than a layer 2 switch
2. A hub doesn’t inspect the information being sent while a layer 2 switch does
3. A hub broadcasts received packets to all other ports while a layer 2 switch doesn’t
4. A hub’s bandwidth degrades with more clients while a layer 2 switch’s doesn’t
5. Layer 2 switches are very common while hubs are already obsolete

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