TX error due to colision or erroneous TX

[Jean Tourrilhes]

Amit Jain wrote :
> I guess I am talking about low-level(802.11) MAC Acknowledgement protocol.
> Acoording to this protocol, for every TX packet, the transmitter has to
> receive an ACK (at physical layer itself, i.e. ACK doesnot propage up the
> protocol stack when ACK is recvd by the original transmitter).
> Only, after the ACK is recvd, another packet is transmitted.
> Otherwise based on timeout and 'number of retries mechanism', same packt
> would be tried by the actual H/w (n/w card)
> Being at low-level, it doesnot care whther it is a broadcast pkt or other.
> ARP kind of thing, or for that matter broadcast packets being not ACKed
> are taken care by higher layetrs in the stack.

	You are a bit slow there, David gave you the proper answer, so
why don't you trust him ?
	Check your tcpdump : before establishing TCP, you need to do
ARP. And if you can find a protocol that can simply and reliably ack
broadcast packets, publish it, because you will receive an IEEE award
for it.

> And I am interested in knowing the transmission that failed because of the
> lack of ACK. Kindly tell me. I guess Jean Tourrilhes wrote an e-mail
> saying that it  is handled as an wireless event in new API. But i figured
> out the new code  and it seems that they use the ev_txexc interrupt. But
> then in my experiment why I am not geting that interrupt ???

	Because the event gives exactly that : failure of an unicast
packet. If you stuff the proper ARP binding in the ARP table (arp -s),
you will see that it works as advertised.

	Jean