Multiple NIC problem, maybe.

enigma87 · 2008-10-21 00:26:14

Any Arch users here ever had multiple nics conflicting with each other? I have an onboard 10/100 nic on this older IBM computer and I put in a marvell gigabit nic. I only have 1 rj45 jack coming from the wall that connects me to the home router so I wanted to connect it like this:

Wall ---eth0 (192.168.0.100) -> Arch IBM -eth1 (192.168.1.1)---> Windows Laptop

with eth0 being 10/100 onboard and eth1 being the marvell gigabit nic. It works fine when i give ONE nic an IP on the home network and I down the other nic, I'm able to ping the gateway and www.google.com, so I know I have my resolv.conf and routing fine with that. But as soon as I give eth1 (with eth0 already working fine on the internet) an IP address I'm unable to ping the gateway using eth0 or anything else. I notice when I rung ifconfig, eth0 has an Interrupt:22. Has anyone ever had this problem?

P.S. I also notice that when I have the problem, it takes a while for the "route" command to show the default gateway I added.

Thanks to anyone who took the time to read this and I hope someone can point me in the right direction

fukawi2 · 2008-10-21 02:12:51

When the 2 interfaces are up and configured, what's the output of 'route -n' ?

enigma87 · 2008-10-21 02:34:07

route -n

Kernel IP routing table
Destination          Gateway                Genmask                  Flags        Metric     Ref        Use    Iface
192.168.1.0         0.0.0.0                   255.255.255.0           U             0           0               0    eth1
192.168.0.0         0.0.0.0                   255.255.255.0           U             0           0               0    eth0
0.0.0.0                192.168.0.1            0.0.0.0                      UG          0           0               0    eth0

I currently don't have all of the routing setup, for the moment I at least want to have both nics up and still be able to ping my router from my arch box.

fresch · 2008-10-21 11:26:24

your routing table looks ok, in addition to that you would need ip forwarding enabled and:
concerning your problem.. I guess the router is missing a route to 192.168.1.0/24,
so if your eth1@ibm gets up, and you try to ping your router.. the actual sender
might be (or obviously is) eth1 with 192.168.1.1.. and since the router does not know where
to send his answers to 192.168.1.0/24.. these packages are going nowhere, (well, they
would _probably_ follow the routers default route.. but thats kinda irrelevant now)

if you dont have access to the router that hides behind the wall, you could use NAT
or, as I would suggest: briding instead of routing

ibm

brctl addbr br0
brctl addif br0 eth0
brctl addif br0 eth1
dhcpcd br0

then your windows box should be able to get its ip configuration by dhcp, too
and you are pretty much done

enigma87 · 2008-10-22 02:25:20

Yeah, I thought that my eth1 would be the one trying to send the ping to the router but I actually put which interface I want to ping the router with (ping -I eth0 192.168.0.1) and still I get no response. Also, the bridging idea, would that allow me to ping my router through my arch box? I thought when I bridged two nics together they get used up? By used up I mean they get rid of their IP's and wont be able to access the internet.

fresch · 2008-10-22 10:11:16

enigma87 wrote:

I thought when I bridged two nics together they get used up? By used up I mean they get rid of their IP's and wont be able to access the internet.

You can still asign ip-addresses to your nics, but that would be an incorrect configuration. in such a case the bridge itself gets the ip-address and your arch would be able to communicate with other boxes just fine

Arch Linux

#1 2008-10-21 00:26:14

Multiple NIC problem, maybe.

#2 2008-10-21 02:12:51

Re: Multiple NIC problem, maybe.

#3 2008-10-21 02:34:07

Re: Multiple NIC problem, maybe.

#4 2008-10-21 11:26:24

Re: Multiple NIC problem, maybe.

#5 2008-10-22 02:25:20

Re: Multiple NIC problem, maybe.

#6 2008-10-22 10:11:16

Re: Multiple NIC problem, maybe.

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