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problem with arp on eth0

Posted: Sun Dec 27, 2015 11:38 pm
by nols-stas
Recently, i have had problem with Internet connection.
It looks like problem with arp.
If i reconnect cable (few times) or connect PC to this cable, and after than again connect raspberry pi everything works fine.

What i should do for solve this problem?

Code: Select all

# ping 8.8.8.8
> From 100.71.155.189 icmp_seq=1 Destination Host Unreachable

# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         100.71.255.254  0.0.0.0         UG    0      0        0 eth0
100.71.128.0    0.0.0.0         255.255.128.0   U     0      0        0 eth0


# ping 100.71.255.254
PING 100.71.255.254 (100.71.255.254) 56(84) bytes of data.
From 100.71.155.189 icmp_seq=1 Destination Host Unreachable

# arp -n -a 
? (100.71.255.254) at <incomplete> on eth0   # - why it incomplete ?

if internet works

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arp -na
? (100.71.255.252) at 0c:a4:XX:XX:XX:XX [ether] on eth0
? (100.71.255.254) at 00:00:YY:YY:YY:YY [ether] on eth0

Re: problem with arp on eth0

Posted: Thu Dec 31, 2015 1:32 am
by nols-stas
do have any idea how solve it? ?

Re: problem with arp on eth0

Posted: Fri Jan 01, 2016 9:38 pm
by larsth
nols-stas wrote:do have any idea how solve it? ?
It is probably a hardware problem. Check the Ethernet cable for damages, and the connectors in each end of the cable.
It is possible that one or more of the thin wires from the Ethernet cable is not connected to the connector. A short-circuit is also possible (that is not dangerous for your hardware).

Another possibility is that one or both connectors had jumped out of the RJ45 socket. There is a plastic thing that holds the Ethernet cable electrically connected. It may have broken off.

/Lars