Understand broadcast level 3

[AdamBonsamar]

Hello,

I don't understand how works broadcast level 3.

For example, I have a host 192.168.1.1 /24 and when I ping (through a switch) to 192.168.1.255, all the hosts :

192.168.1.2/ 25, 192.168.1.2/ 26, 192.168.1.2/ 27 respond. In sipte of their broadcast address is .127, .63, .31

I don't understand why, and have not found the explanation.

Could someone explain to me ? Thakns to all.

[Deepak Kumar]

Hi,

When you are trying to ping the broadcast IP 192.168.1.255, it would forward the L2 broadcast to all other ports in the same VLAN and the devices on same VLAN member ports would de-encapsulate the ICMP echo request, and respond with a unicast echo-reply back to the source address used in the request.

Regards,

Deepak Kumar

[Richard Burts]

I am puzzled how you could have all these in the same network

192.168.1.2/ 25, 192.168.1.2/ 26, 192.168.1.2/ 27

HTH

Rick

[AdamBonsamar]

Thanks both for your replies.

In fact I made a lab with Packet Tracer to simulate that.

I understand that all hosts received the frame since they are in the same vlan, but why the respond to it because when they decapsule they see an broadcast IP wich is not their broadcast address ?

I know that is not the best way to configure a lan (host with different mask) but it was just in order to understand if it was possible or not.