TX error due to colision or erroneous TX

[Bruce Janson]

    From wireless-admin at lists.samba.org Wed Feb 27 12:16:31 2002
    ...
    From: David Gibson <david at gibson.dropbear.id.au>
    ...
    On Tue, Feb 26, 2002 at 07:09:00PM -0500, Amit Jain wrote:
    ...
    > 
    > Just to check whats happening, I configured my laptop to run in Ad-hoc
    > mode with just it as the node in the network. And I ran 'ping' to some
    > hosts and obviously the ping reprted  "Destination unreachable" since the
    > network has only one node.
    
    Specifically "destination unreachable" means that your machine
    received no reply to its ARP query.
    
    > But the surprising thing is that card raised the interrupts corresponding
    > to HERMES_EV_TX and not HERMES_EV_TXEXC. ??
    > 
    > Since there are no other stations in the n/w, it is impossible for my
    > laptop to recevie an ACK for the transmitted packet. So if TX is
    > based on 802.11 ACK protocl, then in this cse function handler
    > corresponding to EV_TXC  should have been called. I do not understand why
    > I am getting "Successful transmission signal" as indicated by EV_TX.
    > (in 802.11 succesfull packet trnasmission means that the packet was
    > trnamitted correctly and subsequent ACK received correctly)
    
    I think this must be because the ARP is failing.  ARP requests are
    broadcast packets, and for obvious reasons these wouldn't be ACKed.
    ...

David,
  Well, not entirely obvious.  If I didn't know in detail how an 802.11 WAN
worked (which I don't, and when did WAN stop meaning Wide Area Network???),
I could imagine an asymmetric network architecture where nominated
central locations (access points?) did acknowledge ARP packets as part
of their provision of a synthetic carrier sense.  But I am perfectly
happy to take your word for it. :-)

Regards,
bruce.