[wellylug] Only one of three ethernet cards works at a time

[Jeff Hunt]

They were completely independent. I borrowed an extra switch from work
and connected to a spare computer. I have since given up. I have
decided there is a fault with the machine that makes it incapable of
distinguishing separate cards. I'm going to salvage the best of the
gear out of this machine and put it onto a motherboard that can
distinguish two ethcards (I only need two). Then I can set this up as
a slave with one card.

For your info I will send the ifconfig data. I did not set it up to
look like this. I wouldn't know how to. What I did was set the three
cards to ip 192.168.1. and then 10 or 11 or 12 to reflect eth0 eth1
and eth2. What I ended up with was quite different which makes me
realise that the network Manager can be quite independent of the real
world. The network manager continues to show things as I expected to
set them. I think that may be the point David is making.

Individuallly they worked but not showing the settings I gave them.
The ifconfig situation is:

eth0      Link encap:Ethernet  HWaddr 00:13:20:bf:a6:91
          inet6 addr: fe80::213:20ff:febf:a691/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:84 errors:0 dropped:0 overruns:0 frame:0
          TX packets:123 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:9183 (9.1 KB)  TX bytes:11175 (11.1 KB)

eth1      Link encap:Ethernet  HWaddr 00:10:b5:fb:6b:3e
          inet addr:192.168.1.12  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::210:b5ff:fefb:6b3e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:116 errors:0 dropped:0 overruns:0 frame:0
          TX packets:144 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:29718 (29.7 KB)  TX bytes:13933 (13.9 KB)
          Interrupt:22 Base address:0xde00

eth1-eth2 Link encap:Ethernet  HWaddr 00:e0:4c:6e:2a:78
          inet addr:192.168.1.10  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::2e0:4cff:fe6e:2a78/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0 frame:0
          TX packets:155 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1062 (1.0 KB)  TX bytes:17133 (17.1 KB)
          Interrupt:21 Base address:0xdd00

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:148 errors:0 dropped:0 overruns:0 frame:0
          TX packets:148 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:13244 (13.2 KB)  TX bytes:13244 (13.2 KB)

Cheers.


On 6/12/11, Daniel Pittman <daniel at rimspace.net> wrote:
> On Fri, Jun 10, 2011 at 17:26, Jeff Hunt <jeffhunt90 at gmail.com> wrote:
>
>> I have an odd problem with a friend's computer. It has three ethernet
>> sockets. One on the motherboard and two cards. I want to set it up
>> masquerading IPs from a second home computer onto an internet
>> supplier, which it has done in the past and which I have caused to
>> happen several times myself on other computers. I installed the latest
>> Ubuntu and so it had to be set up again but now there is a problem.
>>
>> Although all three cards work. As soon as a second switch is turned
>> on, only one card remains active.
>
> When you say that the second switch was turned on, or the second
> socket connected, do you mean that they were connected to completely
> physically disconnected equipment, or were the sockets on the system
> connected to the same broadcast domain?  (eg: to the same switch, or
> to two switches that also had a cable between them, or something like
> that.)
>
> Linux uses the "weak end host model", in which the IP address is a
> property of the *system*, not the network port, even though it looks
> like the later.
>
> That means that if you plugged two cables into a single broadcast
> domain, Linux will pick *one* of them to use for all communication,
> out of the box.  Which might explain what you saw: the second port
> was, essentially, ignored even though it "worked", and the preference
> was quasi-random.
>
> Daniel
> --
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> ✉ Daniel Pittman <daniel at rimspace.net>
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