Arch Linux

slot

Member

Registered: 2008-09-08

Posts: 67

Eth0 connectivity depends on eth1 being plugged in?

The problem is that if I pull the plug out on eth1 (PCI) then eth0 (onboard) connectivity stops.
If I pull eth0 then eth1 continues to respond, while eth0 does not.

I have seen this now on two different machines, so it seems to me to be a 'feature' of Arch.
I am a bit unhappy about it as it somewhat defeats the intention with redundancy.
Any take on that?

I am on Arch64
I just follow the beginners guide and install arch with two ethernet cards, one builtin and one PCI.

I edit rc.conf:

eth0 = "dhcp"
eth1 = "eth1 10.10.11.242 broadcast 10.10.11.255 netmask 255.255.254.0"
INTERFACES=(eth0 eth1)
gateway="default gw 10.10.10.1"
ROUTES=(gateway)

eth0 get its IP:

eth0      Link encap:Ethernet  HWaddr 00:23:54:40:48:BB
          inet addr:10.10.10.69  Bcast:10.10.11.255  Mask:255.255.254.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1258618 errors:0 dropped:0 overruns:0 frame:0
          TX packets:846 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:99922868 (95.2 Mb)  TX bytes:62041 (60.5 Kb)
          Interrupt:29 Base address:0xe000

eth1      Link encap:Ethernet  HWaddr 00:50:FC:22:F7:D4
          inet addr:10.10.11.242  Bcast:10.10.11.255  Mask:255.255.254.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:426 errors:0 dropped:0 overruns:0 frame:0
          TX packets:94 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:44279 (43.2 Kb)  TX bytes:11986 (11.7 Kb)
          Interrupt:17 Base address:0xc000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:799 errors:0 dropped:0 overruns:0 frame:0
          TX packets:799 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:48572 (47.4 Kb)  TX bytes:48572 (47.4 Kb)

Last edited by slot (2010-02-15 15:45:03)

jac

Member

From: /home/jac

Registered: 2009-05-19

Posts: 431

Website

Re: Eth0 connectivity depends on eth1 being plugged in?

I think the title is a typo. How do you unplug it? Do you just mean taking the ethernet cord out? Did you set up static device naming, or do they get assigned whatever name is available?
Unfortunately I don't know too much about networking, but maybe it has to do with the fact that eth1 is static and eth0 is dhcp?

Edit: For testing the last suggestion, can you try switching their configs? See if eth0 is done statically if it will work with the (then, dhcp configured) eth1 unplugged.

Last edited by jac (2010-02-12 14:25:11)

slot

Member

Registered: 2008-09-08

Posts: 67

Re: Eth0 connectivity depends on eth1 being plugged in?

I think the title is a typo.

You´re welcome to suggest something better

How do you unplug it? Do you just mean taking the ethernet cord out?

Yes, but the same happens when it boots with one cable plugged only

Did you set up static device naming, or do they get assigned whatever name is available?

No I didn't, but I think they'r fairly stable, and I don't care which one gets the IP's

Unfortunately I don't know too much about networking, but maybe it has to do with the fact that eth1 is static and eth0 is dhcp?

Edit: For testing the last suggestion, can you try switching their configs? See if eth0 is done statically if it will work with the (then, dhcp configured) eth1 unplugged.

Yes - I will.

slot

Member

Registered: 2008-09-08

Posts: 67

Re: Eth0 connectivity depends on eth1 being plugged in?

Edit: For testing the last suggestion, can you try switching their configs? See if eth0 is done statically if it will work with the (then, dhcp configured) eth1 unplugged.

Then they get the same IP naturally as the dhcp server recorded the static number. They are still linked, but now going both ways. Pull out any one of the cables and there is no response.

jac

Member

From: /home/jac

Registered: 2009-05-19

Posts: 431

Website

Re: Eth0 connectivity depends on eth1 being plugged in?

You´re welcome to suggest something better

What about "eth0 connectivity depends on eth1 connectivity?" Unless I'm misunderstanding your problem, in which case eth0 does need to be plugged in to be connected.

I think you probably know more networking than I do, but is there any reason why you're doing one static and one dhcp? There are lots of smart people here, I'm sure somebody has an answer or a bug report to show you.

sdolim

Member

Registered: 2010-01-20

Posts: 67

Re: Eth0 connectivity depends on eth1 being plugged in?

The problem may be dhcp-related.  There've been a lot of posts recently about people having trouble with dhcp, particularly with getting the gateway set up.

As a test of this idea, if you were to do this:

eth1 = "dhcp"
eth0 = "eth1 10.10.11.242 broadcast 10.10.11.255 netmask 255.255.254.0"

Does the problem switch to the other interface?

Sin.citadel

Member

Registered: 2008-01-22

Posts: 267

Re: Eth0 connectivity depends on eth1 being plugged in?

I think, that since you assigned the default route statically, and since both eth0 and eth1 are in the same subnet, the default gateway so assigned is for the eth1 device, so when u pull out the eth1 cord, packets cannot be forwarded to the gateway since the default gateway uses eth1 device.

try using,
route add default gw 10.10.10.1 dev eth0

slot

Member

Registered: 2008-09-08

Posts: 67

Re: Eth0 connectivity depends on eth1 being plugged in?

is there any reason why you're doing one static and one dhcp?

Just that I wanted to know the IP adress of at least one of the interfaces. On the other machine where I saw the problem both are static.

slot

Member

Registered: 2008-09-08

Posts: 67

Re: Eth0 connectivity depends on eth1 being plugged in?

I think, that since you assigned the default route statically, and since both eth0 and eth1 are in the same subnet, the default gateway so assigned is for the eth1 device, so when u pull out the eth1 cord, packets cannot be forwarded to the gateway since the default gateway uses eth1 device.

try using,
route add default gw 10.10.10.1 dev eth0

Thanks, I will  try that one, I am on  vacation this week, so it will be next week before I can pull the plug again ;-)

Urfaust

Member

From: Germany

Registered: 2009-01-30

Posts: 164

Re: Eth0 connectivity depends on eth1 being plugged in?

How do you test the connectivity? Ping from another machine?

slot

Member

Registered: 2008-09-08

Posts: 67

Re: Eth0 connectivity depends on eth1 being plugged in?

Yes I ping from another machine and also ping out from the same machine - both get blocked

Urfaust

Member

From: Germany

Registered: 2009-01-30

Posts: 164

Re: Eth0 connectivity depends on eth1 being plugged in?

Try to put one device in another subnet.  I think it doesn't work if both cards are on the same subnet. Had the same problem a few weeks ago with a windows server.

tomk

Forum Fellow

From: Ireland

Registered: 2004-07-21

Posts: 9,839

Re: Eth0 connectivity depends on eth1 being plugged in?

You don't need two concurrent net connections. If you need redundancy, do it with a daemon that watches your interfaces and brings the second one up if the first one goes down. ifplugd comes to mind, and there are probably other options.