Thanks for the quick reply. I have tried that, and you are correct. In
addition to that question, when I set the sender to send one unicast pkt to
the sniffer node(in promisc mode), it still sees 4 pkts. I know it is not
really meaningful, just curious what is going on here.



On Fri, Jan 29, 2016 at 11:35 PM, Oleg Hahm <[email protected]> wrote:

> Hi Sugang,
>
> Michael's explanation is 100% correct. You can try setting the retries on
> the
> sender to another value by calling:
> `ifconfig <ID> set csma_retries <NUMBER>`
> and should see different results.
>
> Cheers,
> Oleg
>
> On Fri, Jan 29, 2016 at 01:57:34PM -0800, Michael Andersen wrote:
> > Hi
> >
> > Generally if you are sending unicast, and there is no receiver, you will
> > see multiple copies of the packet as the transmitter is expecting an ACK,
> > and will retry until it gets one or it reaches the max number of retries.
> > There are no ACKs on broadcast, so the transmitter will only send one.
> >
> > Regards
> > Michael
> >
> > On Fri, Jan 29, 2016 at 12:51 PM, Sugang Li <[email protected]>
> wrote:
> >
> > > Hi all,
> > >
> > > I am working on sniffer testing over SAMR21 board,  here is my setup:
> > >
> > > 1. I have one node to send mac packet by calling txtsend.
> > > 2. Another node is working as a Sniffer which is in the Promisc Mode
> set
> > > by "ifconfig set promisc"
> > >
> > > However, whenever the transmitter send one pkt via unicast, the sniffer
> > > will receiver will receive 4 pkt (each of them will have a different
> header
> > > memory address).   If it sends via broadcast mode, the sniffer only
> got one
> > > pkt (this is correct).
> > >
> > > Any idea about this weird situation?
> > >
> > > Thanks,
> > >
> > > Sugang
> > >
> > > --
> > >
> > > *WINLAB, Department of Electrical and Computer Engineering*
> > >
> > > *Rutgers,the State University of New Jersey*
> > >
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>
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-- 

*WINLAB, Department of Electrical and Computer Engineering*

*Rutgers,the State University of New Jersey*
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