Gratuitous ARP
"Steve Trigero seecwriter-/[email protected] [rabbit-semi]" <[email protected]> Tue, 9 Jan 2018 18:41:02 +0000 (UTC)
| Newsgroups | gmane.comp.hardware.rabbit-semiconductor |
|---|---|
| Message-ID | <[email protected]> |
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I have an RCM3900 module that has a TCP connection with a host. The module =
is receiving TCP packets at about a 1-second rate. So everything is humming=
along with the host sending TCP packets requesting status info, and module=
responds with the data.=C2=A0 After a=C2=A0some time, minutes to hours, of=
running, the module issues 2-gratuitous ARP packets, about a second apart.=
And upon receiving the next TCP packet, the module responds by closing the=
connection.
Both gratuitous ARP packets have the same ARP data:
Opcode: request (1)Sender MAC address: 00:90:c2:f7:fd:36Sender IP address:=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 192.168.1.64Target MAC address: 3f:c7:01:00:=
b4:e5Target IP address:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 192.168.1.64
The target MAC doesn't appear to be valid.=C2=A0 According to what I read, =
an opcode of 1 is an ARP Probe or an ARP Announcement.=C2=A0If a probe, the=
sender IP and target MAC are supposed to be set to 0, and the target IP se=
t to the IP in question (to see if it's taken), and if an announcement, the=
sender IP and target IP are set to the same IP and the target MAC is set t=
o 0 to announce that this NIC is using this IP address.=C2=A0 The format of=
the above doesn't fit either format.=C2=A0=C2=A0Could this=C2=A0be indicat=
ing an IP conflict?=C2=A0 There is no response to either message.
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<p><div style="font-family:times new roman, new york, times, serif;font-size:16px;"><div>I have an RCM3900 module that has a TCP connection with a host. The module is receiving TCP packets at about a 1-second rate. So everything is humming along with the host sending TCP packets requesting status info, and module responds with the data. After a some time, minutes to hours, of running, the module issues 2-gratuitous ARP packets, about a second apart. And upon receiving the next TCP packet, the module responds by closing the connection.</div><div><br></div><div>Both gratuitous ARP packets have the same ARP data:</div><div><br></div><div>Opcode: request (1)</div><div>Sender MAC address: 00:90:c2:f7:fd:36</div><div>Sender IP address: 192.168.1.64<
/div><div>Target MAC address: 3f:c7:01:00:b4:e5</div><div>Target IP address: 192.168.1.64</div><div><br></div><div>The target MAC doesn't appear to be valid. According to what I read, an opcode of 1 is an ARP Probe or an ARP Announcement. If a probe, the sender IP and target MAC are supposed to be set to 0, and the target IP set to the IP in question (to see if it's taken), and if an announcement, the sender IP and target IP are set to the same IP and the target MAC is set to 0 to announce that this NIC is using this IP address. The format of the above doesn't fit either format. Could this be indicating an IP conflict? </div><div>There is no response to either message.</div><div><br></div><div><br></div></div></p>
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