Difference between Ethernet and Wi-Fi

To tell any two modes of communication, the 2 layers of the OSI model of importance are the Physical Layer (I) and the Data Link Layer (II). Generally, these layers determine the level of speed, reliability and security.

Physical Layer is about signaling format, topology, and media of transmission.

Topology refers to how devices are set up physically and logically. Example — Star, Bus, Mesh, etc.…

Signaling format can be radio, light, electric.

Data Link Layer is about MAC address, and frame.

All the other 5 layers are pretty much the same for different TCP/IP networks.

OSI Model

Let’s now try to differentiate 802.3 Ethernet from 802.11 Wi-Fi —

On basis of Physical Layer-

1. Cabling (Media) — Ethernet uses UTP or fiber optics or co-axial cables, while Wi-Fi transmits signals through air.
2. Topology — The most popular Ethernet topology is star-bus. While, Wi-Fi can be star or fully meshed.

On basis of Data Link Layer-

1. MAC — Ethernet uses CSMA/CD while Wi-Fi uses CSMA/CA. https://medium.com/networks-security/carrier-sense-multiple-access-with-collision-detection-csma-cd-4ef9cb792da7 https://medium.com/networks-security/csma-ca-wireless-medium-access-control-protocol-e2139b04c73a
2. Devices — Layer 2 device for Ethernet is a switch. While layer 2 device for Wi-Fi is an access point — a bridge between Ethernet & Wi-Fi.
3. Frame — Wi-Fi has 3 types of frames:

• Management Frame — It is involved in wireless association, re-association, probe, and beacon.
• Control Frame — Related to Medium Access Control and data delivery. Example — RTS/CTS frames in CSMA/CA.
• Data Frame — Responsible for carrying data between sender and receiver.

MAC header comprises of Preamble, Destination, and Source address

The first part is Preamble, which tells the receiver that a frame is coming and where the frame starts.

Note: A Data Frame is a data structure that organizes data into a 2-dimensional table of rows and columns, much like a spreadsheet.

The Preamble is followed by the destination MAC address and sender’s MAC address. The Type, tells the type of data — IPv4 or IPv6. Data is the payload that a frame carries, such as IP packet. The last part, FCS, is an error checking mechanism to ensure the frame is intact.

Much larger MAC header

The first part, Frame Control holds the information about what protocol is used, what type of security, or type of frame is used. Duration indicated how long the transmission will take, so that other devices know when the channel will be available to them again. Address 1 is the source’s MAC address. Address 2 refers to the transmitter address (Access Point’s MAC Address). Address 3 refers to the receiver’s address (also refers to Access Point’s MAC Address). The Sequence Control indicates how a large data packet is fragmented. Address 4 is referring to the recipient MAC address.

Note: Since the Wi-Fi MAC header is much larger than that of Ethernet, it is understandable that Wi-Fi is no as efficient as Ethernet.