Question about switch operation..

Ok this is the response from one of the brilliant(Smartest guy I know) guys I know when I told him what happened. His theory from the beginning was that ARP does not operate in different networks.

"That's impossible. His switch may be not a layer 2 one. Since you said that I did the configuration here in my office using a switch and two LAPTOPs, I could not ping the other one. In addition I took a wireshark trace, which shows that PC A does not even send an ARP"

So I have to ask. What is the switch you used? What is the model? Any possibility that It could be a layer 3 switch ?

Loosend

tell us what you did in your experiment

Loosend,

It's a small 8 ports layer 2 switch. And I tried it today on a Cisco 24 ports 2950 switch (layer 2). It works again.

It did not work in Packet Tracer because the receiver (PC2) did not reply for the ARP. Although the sender (PC1) sent the ARP request.

I have to say here that this can be implementation dependent. i.e I know now Windows sends and replies for ARP to/from other networks. However, I'm not sure what would Linux or Mac do.

I used an 8 port Dlink switch but the 2 PCs werent connecting.


but since PC 1 will not make an arp broadcast if it figures the IP is on different subnet, it will send the message to the default gateway and you have told PC one that the default gateway is 192.128.2.1. so the default gate way will see a message address to itself so it will respond

I used an 8 port Dlink switch but the 2 PCs werent connecting.

I wonder how is this working only with me!! . sose, make sure that you don't have any active gateways on any other interfaces on both PCs. For example, if you have a wireless NIC using DHCP, make sure you disable it. Also make sure that Windows Firewall is disabled (or allow ICMP to pass). Needless to say here that you should set BOTH PC's gateways to the IP of the other PC.