Re: [lwip-users] tcp_enqueue problem, using socket:

[Jonathan Larmour]

Piero 74 wrote:
> here i attached a wireshark file...
> 
> I didn't understand what is the problem....
> Anyone can explain me??
> 
> my ip board is 192.168.0.101 <http://192.168.0.101>
> pc ip is 192.169.0.1 <http://192.169.0.1>

Great! That's exactly what was needed. According to that, clearly the PC is
not ACKing the further sends, hence you eventually running out of send
buffer space.

Why is it not acking? According to my dump, the first unacked packet from
your ip board to the PC has a bad checksum:

09:28:34.359638 00:bd:33:02:64:24 (oui Unknown) > 00:c0:f0:52:fe:91 (oui
Unknown), ethertype IPv4 (0x0800), length 248: (tos 0x0, ttl 255, id 3,
offset 0, flags [none], proto: TCP (6), length: 234) 192.168.0.101.dnp >
192.168.0.1.4539: P, cksum 0x018f (incorrect (-> 0x3182), 195:389(194) ack
1 win 2048

Everything in the packet superficially looks ok (lengths, src and
destination IPs etc.) but either the packet has got corrupted, or somewhere
in your processing of the packet you have modified it without recalculating
the checksum.

Jifl
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