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No replies from DHCP requests

Posted by stemora on August 17, 2017

Hello there, I'm compiling FreeRTOS 9.0.0.0 + TCP 160919 for LPC1778. On the run of the board I send the DHSP request: sniffing with wireshark I see 3 DHCP requests and a number of ARP requests (?). No reply from the DHCP sever.

1003 68.228709 0.0.0.0 255.255.255.255 DHCP 309 DHCP Discover - Transaction ID 0x2ae6 1022 81.701502 0.0.0.0 255.255.255.255 DHCP 309 DHCP Discover - Transaction ID 0x2ae7 1029 91.951347 0.0.0.0 255.255.255.255 DHCP 309 DHCP Discover - Transaction ID 0x2ae8 4979 122.497600 Metrohm10:15:11 Broadcast ARP 60 Gratuitous ARP for 0.0.0.0 (Request) 8055 152.497153 Metrohm10:15:11 Broadcast ARP 60 Gratuitous ARP for 0.0.0.0 (Request) ....

Frame 1003: 309 bytes on wire (2472 bits), 309 bytes captured (2472 bits) on interface 0 Ethernet II, Src: Metrohm_10:15:11 (00:12:13:10:15:11), Dst: Broadcast (ff:ff:ff:ff:ff:ff) Internet Protocol Version 4, Src: 0.0.0.0, Dst: 255.255.255.255 User Datagram Protocol, Src Port: 68, Dst Port: 67 Bootstrap Protocol (Discover) VSS-Monitoring ethernet trailer, Source Port: 12

Checking on the DHCP server we don't see any request (?): possibile that the request is blocked by a switch ? If yes,why? My guess is that the package is not malformed .. is it ?

Thanks


No replies from DHCP requests

Posted by heinbali01 on August 17, 2017

Hi, I attached a simple DHCP conversation for comparison.

possible that the request is blocked by a switch

Switches will recognise DHCP packets and they will let them through.

Have you defined ipconfigUSE_DHCP_HOOK in your project? If so, what does your implementation of xApplicationDHCPHook() look like?

What you can try is install a temporary DHCP-server on your laptop:

https://sourceforge.net/projects/dhcp-dns-server/files/Dual%20DHCP%20DNS%20Server/

and see if your devices will get an answer from this DHCP server. When that works, you are one step further.

Can you ping your DHCP server from your laptop? Or, more complicated to test, if you give a fixed IP-address to your device, can it ping to the DHCP server?

Attachments

dhcp_packets.pcap (1327 bytes)

No replies from DHCP requests

Posted by heinbali01 on August 23, 2017

Hi there, did you get any further with DHCP ? If not, can you attach a PCAP that shows the DHCP packets ?


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