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I tried to transmit a video with the latest OFDM reference design. The application layer software was VLC player. However, no video was received on the receiver's end.
I tried to find out whether the warp MAC code was passing any packet to the ethernet on the receiver's side. I have found that the packets are being sent to the ethernet as the printf message in the following code is being displayed on Tera Term Pro.
int receiveGoodPacket(Macframe* packet) {
....
....
....
if(warpmac_addressedToMe(packet)){
....
....
warpmac_sendEthernet(packet);
printf("packet was sent over the ethernet");
....
}
.....
}
However, the number of packet received shown on the Local Area Connection Status on WINDOWS XP is shown to be zero ( Windows is showing that the "connection status" to be "connected", so there is no problem in the ethernet cable). Ethereal too shows the number of packets received to be zero.
Could you please suggest what could be the problem? Thank you!
Last edited by vikasg (2007-Jun-27 14:16:41)
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Does your code actually call the function to send the received packet over Ethernet? For example, the UniMac code from the workshop doesn't do this (hence the 'uni'-directional). Check your code against the latest OFDM reference design, WAPRMAC and CSMA code to see if you're missing any function calls.
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I am using the latest OFDM reference design v04 and CSMA code as given in the design.
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If you connect the PCs together directly (over a wire; no WARP at all), does it work? Is the firewall enabled on the destination Windows PC? Do you see the destination WARP board's Ethernet activity LED blink?
Are you using the bitstream from the reference design download, or a locally generated one? If you re-compiled the code, double check the linker script.
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The video transmission was working correctly and windows was showing that packets are being received with the OFDM version present in http://warp.rice.edu/bigFiles/warpmac_labs.zip.
However, it is with your latest version of Ofdm version 04 that neither windows is detecting received packets nor does the video play on VLC player.
Interestingly, as soon as we switch on ethereal software to capture packets on this link, windows immediately starts recording received packets. Moreover, now if you switch off the ethereal again, windows again shows no activity on received packets side i.e. the received packet count stops increasing. Its almost as if ethereal is "sucking up" packets on the ethernet link!
Even with ethereal on, video does not play on VLC player.
Please suggest something.
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vikasg wrote:
Interestingly, as soon as we switch on ethereal software to capture packets on this link, windows immediately starts recording received packets. Moreover, now if you switch off the ethereal again, windows again shows no activity on received packets side i.e. the received packet count stops increasing. Its almost as if ethereal is "sucking up" packets on the ethernet link!
If you can get Windows to show received packets without making any changes to the code running on WARP, the problem is likely with the configuration of your PCs. It sounds like Windows is accepting packets only when Ethereal puts the NIC in promiscuous mode, which is a sign that the packets it's receiving are addressed to some other MAC address.
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The reason I think the problem is not with the PC configuration is that Windows receives packets when I run the code http://warp.rice.edu/bigFiles/warpmac_labs.zip. It is only with Ofdm version 4, that the Windows does not receive packets. Could you suggest any probable reason? Thank you.
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Please verify you're setting things up properly for use with the reference design, detailed at http://warp.rice.edu/trac/wiki/OFDMReferenceDesign. The configuration of local IP addresses and WARP board DIP switches are both important. Also, it would be very helpful if you attempted the debugging steps listed in reply to your earlier posts.
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