Hello Narad
The truth is that Ethernet has three different formats. All of those things you mention have to do with the format of the Ethernet header, and what information it contains.
Remember the OSI model? Ethernet “lives” in the Data Link layer. The Data Link layer is separated into two sublayers. The upper sublayer is called the Logical Link Control or LLC, while the lower sublayer is called the Media Access Control or MAC.
Now the three formats essentially determine what is contained within the Ethernet header.
- The IEEE 802.3 defines the part of the header that is included in this lesson. This is also known as Ethernet II. This is the most commonly used Ethernet.
- In addition to 802.3 IEEE 802.2 is added as an additional section to the header, which exists within the LLC sublayer.
- Thirdly, you can have the use of 802.2 including what are known as subnetwork access protocol (SNAP) extensions that add mechanisms for multiplexing on networks using 802.2.
These formats use different frame types and different MTUYs but can coexist on the same physical medium. The following image shows the difference in the headers of these types of ethernet frames and the fields that correspond to each standard.
I hope this has been helpful!
Laz