net problem

recently we try to use qnx6.2 on one IPC,it has 6 port for net,en0-en5,qnx can find the 6 port with driver ‘speedo’, for en0-en3 it can ping to itself,en4-en5 can’t ping to itself,and all the port can’t ping to other computer,under windows it can work very well,Could you tell me how to do? thanks

the net card can be found,but it can’t ping to other computer,why?

please give me some advice

oh,it can ping finally,but it’s very strange when i change ip from one port to another by philp,it can’t be valid at once,when i reboot the system it’s OK,why?

Because of ARP cache?

please tell me the details.

NIC cards are not monitoring for packets that happen to have the required IP address, nor are they typically monitoring all packets. Instead they are monitoring for packets that have their MAC address. So if you are a router, for example, and you want to send a packet to specific IP address, and you don’t know which MAC address it is at, you need to find out. You find out with the ARP protocol. I believe you issue a broadcast of an ARP request. You then cache the result so you don’t have to do this each time. If the Node you are communicating to changes the MAC address associated with IP, you don’t know this immediately.

Critic’s welcome, that’s my vague understanding.