How ethernet switch is work?

Thread Starter


Joined Nov 28, 2016

I have seen many videos in youtube regarding Ethernet Switch functionality. I understand that video well. But still i have a query. I have FPGA Based hardware for Power Electronics control application and in that board having Ethernet connectivity. I have successfull in Modbus TCP/IP to interface with HMI for Human Interface. Now i want to connect multiple HMI's and Energy meters through Ethernet Switch creating local network. My FPGA Hardware is act as Server.

My questions is, How the ethernet switch will work when two clients will send request to Server at the same time?

Nandish Jasani.


Joined Feb 25, 2011
Well assume IP V4 here, and a none managed network ( most small ones fall into the category )

The switch, is a self learning unit.

Each and every Ethernet end point, will as you have read, have a unique MAC address.
each and every Ethernet system, as you also know , has a means of assigning every end point on the network a unique IP address.

Each and every packet of data sent over the Ethernet, contains a header, that states which ip its from and which ip its going to.

The switch, starts out with know knowledge of what Ip is on each of its ports,
so initially it sends all packets it receives out to all ports. The switch , mainly by listening to packets, learns which ports which IP addresses should be sent to, and over time, if it receives a packet for a particular Ip address it knows about, only sends out on the port that has that Ip on.

Its not perfect, and there are rules for the switch to keep a track of things, and account for things being disconnected and re added, and rules that allow packets to be broadcast to all ports, or even a sub set of ports, but thats the icing on the cake.