Hot!DHCP Discover Message blocked on net switch

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jautry
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2017/10/11 12:44:26 (permalink)
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DHCP Discover Message blocked on net switch

I am trying to use a harmony 1.07 implementation with an HDBT LAN link/switch.  For some reason the DHCP discover message is not passed through.  I tried it with some other devices, and it worked, it only seems to not work with the Microchip Net Stack.  I am searching through what differences there may be between the messages and have modified the stack to see if I can get the message through, but no luck so far.  What I noted also, is that the working units have the no-fragment flag turned on.  Where can I set this flag in the Microchip stack, I cannot seem to find it.
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    RISC
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    Re: DHCP Discover Message blocked on net switch 2017/10/11 13:37:31 (permalink)
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    Hi,
    If my memory is correct, the discovery packet is a simple UDP packet (check with Wireshark).
    If it does not come out it means there is some filtering going on in your special "HDBT LAN link/switch".
    Can you confirm that your observation is based on wireshark and not on the fact that the discovery utility does not see your PIC32 board ?
    Regards
     
     
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    jautry
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    Re: DHCP Discover Message blocked on net switch 2017/10/11 14:15:14 (permalink)
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    I am using wireshark to verify.  I tracked the xmt through ipv4 module and it goes at least that far, but never see it out of the switch.  I also tried going to static addressing, and no ARPs get through, it just does not like something that is common in the protocol.
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    RISC
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    Re: DHCP Discover Message blocked on net switch 2017/10/11 14:59:36 (permalink)
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    Hi,
    If even ARP packets don't go through, your switch really has an issue...
    Is you switch "managed" ?
    Maybe try to do a factory RESET and see what happens ?
    Connect a couple of PCs to see if ARP packets go in and out
    Regards
     
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    rainad
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    Re: DHCP Discover Message blocked on net switch 2017/10/11 15:01:37 (permalink)
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    If you verify with wireshark, do you see the DHCP packets transmitted by PIC32 (there should be retries)?
    Another flag that comes to mind is the unicast vs. broadcast in the DHCP message.
    Does the switch support unicast DHCP messages?
     
    P.S. I fit doesn't work with static address either, then you really have a problem with that switch.
    Change it with another one and see if the problems are solved.
     
    post edited by rainad - 2017/10/11 15:03:29
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    jautry
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    Re: DHCP Discover Message blocked on net switch 2017/10/11 15:16:50 (permalink)
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    I have tried it on two units with the same results.  I was going to attach a wireshark log of a working and non-working IOT device discovery packet, but the attachment option denies access.
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    jautry
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    Re: DHCP Discover Message blocked on net switch 2017/10/12 19:15:42 (permalink)
    5 (1)
    Ok, I finally got it to work, but this is really strange.  I had to place a netgear switch between the HDBT LAN and IOT device to act as translator or buffer, not sure.  I am no net expert, but is there some kind of PHY encoding going on that could be confusing the HDBT LAN and the switch is doing the translation??  I cannot believe it is a signal issue since the net link is up.
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    jautry
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    Re: DHCP Discover Message blocked on net switch 2017/10/13 11:09:09 (permalink)
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    I found out by removing the TCPIP_ETH_OPEN_AUTO  option in the setup, things started working fine and I could communicate normally through the HDBT LAN connection.  I think this reflects the control flow but not sure why it would cause a communications problem.
    #8
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