|Subject:||Re: [lwip-users] FW: Problem with renewing DHCP after link down/up with the new LWIP V2.0.2|
|Date:||Tue, 3 Apr 2018 11:43:54 +0300|
OK, I have already explanation of my strange problems with the DHCP renew. The problem was, unfortunately, in my code ☹. The stack stores a chained pcbs for all UDP connections. DHCP creates such connection when it is started. But because of my mistake, I brake the chain and I'm losing connection with the pcb, created from the DHCP (the first one that was created after power on). Therefore by renew the stack doesn't find a pcb for port 68. After a small fix in my code all works just fine and it is so simple as it should be.
> -----Original Message-----
> From: lwip-users <lwip-users-bounces+simeon.trifonov=amk-
> address@hidden> On Behalf Of address@hidden
> Sent: Friday, March 30, 2018 4:10 PM
> To: Mailing list for lwIP users <address@hidden>
> Subject: Re: [lwip-users] FW: Problem with renewing DHCP after link
> down/up with the new LWIP V2.0.2
> On 30.03.2018 13:01, address@hidden wrote:
> > I replaced the function dhcp_renew() with dhcp_network_changed().
> > After power on, the dhcp works fine again (the complete log is
> > attached). The first strange thing for me is the ARPs that follow. The
> > devices askes who has IP address 192.168.5.60, but it is his new address... Is
> that normal?
> Yes. The client checks if the address assigned by the server is really unused.
> This is sometimes called "address collision detection" (ACD) and is e.g.
> required for Ethernet-IP at least... Just yesterday I had a DHCP server
> assigning a duplicate address, where this helps :-)
> > The other strange thing is that if I disconnect the Ethernet cable and
> > connect it again (in the same network), all things that follow (after
> > line
> > 12) are not understandable for me.
> The IP checksum of the DHCP ACKs are 0, but that might be checksum
> offloading because you monitor on the host that is running the DHCP server?
> If not, it's correct that lwIP does not get them.
> > I seems that my device doesn't receive the frames from the DHCP
> > server.
> Hmm, looking again, it seems that lwIP just does not receive the answers as
> valid DHCP packets, as it sends an ICMP "port unreachable" as response.
> That's strange... I don't think that's a problem with your tunneling thing...
> lwip-users mailing list
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