Ethernet

I learned about Ethernet. 

Ehternet is a physical topology. 

Here are the two structuresof Ethernet.

 

• Bus
  • All nodes in same collision domain (nodes can collide with each other).
• Star
  • Active switch in center
  • Each spoke runs a seperate Ethernet protocol. (nodes do not collide with each other).

Also, Ethernet has many different standareds.

• Common MAC protocol and frame format. 
• Different Speeds: 2Mbps, 10Mbps, ...
• Different physical layer media: fiber and cable. 

These are the features of Ethernet switch.

So, it is quiet complicated to understand the process. Let's have an example.

Example

In this case, A sends a frame to G. And, G replies to A. 

1. A sends to S1. --> Now, S1 know A is accessible through 3. 
2. S1 checks others(B,C) if there is a G in it. At the same time, S1 sends to S4. --> Now S4 knows A is accessible through port 1. B, C are not G, so drop the packet!
3. S4 sends to S2 and S3. --> S2 and S3 knows which port they can access to A.
4. S2 and S3 check their packets. 
5. S3 found G through port 3. --> Now, S3 knows G is accessible through port 3. 
6. S3 sends to S4. --> Now, S4 knows G is accessible through port 3.
7. S4 sends to S1. --> Now, S1 knows G is accessible through port 2.
8. S1 sends to A. 

 

It would be better to draw this table to know how ethernet switch woks in our network.