Theme: Organization of work of local networks. Networking by domain structure. Contents

The Ethernet protocol

The term “protocol” refers to the customary sequence of communication messages exchanged among devices that they use to get each other’s attention, to indicate that they are ready to communicate, to pass data between them and to provide the status of the messages exchanged.  In modern networking, there are many protocols at many levels, each with its own specific purpose.  In casual conversation, you may hear the term "handshake" used as a synonym for the term "protocol”.

The ethernet protocol is one where devices get each other’s attention by sending communications messages or “packets” onto the network whenever they need to.  Since one device on a network could send a packet at exactly the same time as another, packet “collisions” can occur which nullify the packets of both senders, delaying the transmission and requiring them to send their packets again, hopefully not at the same time.

Hubs

In ethernet’s early years all devices in an organizational group typically were connected to a “hub”.  A hub is a device to which all devices sharing a physical network can be a physically connected to form a “Local Area Network” or “LAN”.  Hubs do little more than enable the electrical currents from a computer sending a packet to pass to all other devices connected to it.  Since a hub was the electronic equivalent of shouting in a room as necessary, as the number of devices increased, the number of collisions increased and LAN performance ground to a halt.  In a hub-centric environment, the message packets being sent by each device that is connected to the hub can be “seen” by every other device on the hub whether they are involved in the conversation or not.  So, hubs can facilitate message eavesdropping. 

Switches

To remedy the performance and privacy issues of hub technology, "switch” technology was developed which greatly improved on the hub functionality by adding logic to:

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  Pace the packets being transmitted onto the network,
  
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  Direct messages only to the devices that are involved in the communication resulting in:
  
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    A significant reduction in packet collisions and the communication burden for all connected devices,
    
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    Improved network performance, and
    
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    Enhanced security since message data packets are not broadcast to all devices, limiting their ability to “eavesdrop”.