our prototype can only pinging through hub. it wont work on switch. we use the same network cable, same condition. when pinging through hub, it works very well; when connect it to the switch directly, it stops pinging. Why? What is the potential problem?
Please anyone has an idea.
Can you give a little more background info? By prototype do you refer to the ethernet interface as well? Could be something to do with the MAC address and ARP. A hub broadcast packets on all ports, while a switch only routes packets to a port where a particular MAC address is known to exist. ARP is used to correlate an IP Address, assigned by the user to a MAC Address permanently assigned to an interface. Where did you acquire the MAC Address for the prototype?
When doing ethernet related development, you should be able to use respective tools, e.g. wireshark, to debug the communication.
ICMP echo request ("Ping") needs to be preceeded by determining the peer's MAC address trough ARP (performed by the TCP/IP stack
automatically), you should trace the complete action to see, where it fails.