UDP Send/Receive problem on the same port
 

Hi,
I have a packet generator connected to my MAC that sends 100 UDP packets to my port 3000(It uses port 4000 to send these packets). I have a loop that receives these packets (recvfrom(..)) and send them back immdeiately, untouched and count them. However, these packets gets to my MAC and all the way up the stack (netdev->stats.rx_packets = 100). But my recvfrom(..) only receives 63 of these and sendto(..) is called 63 times. However, the packet generator receives only 3 packets at all time. Any suggestions as to what might be happening here ? What happened to the missing 37 packets ? And why nedev->stat.tx_packets does not agree with how many times sendto() has been successfully called ? I doubt if it is prohibited to send and receive using the same socket bounded to my receive UDP port...is it ? Should I use two different sockets and bind them to two different port, one for receive and one for send ?
Thanks in advance for any suggestions.

Are you checking for errors being returned from the sendto() call?

Of course. sendto() always returns the exact number of bytes given to it to send. Today I am delving into the kernel and check the transmit routine..it should be called at least as many times as my sendto() is called.

Are you sure you aren't over running the receive buffers and dropping packets?

No, that's not the problem at all. The weird thing is sendto(..) is called and returns 63 times but the MAC driver's
transmit routine in kernel is only called 3 times. Have no idea what happened to the rest of the packets. I thought
sendto() returns only when the packet is passed to transmit routine.