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3 NIC's are fine, why does adding a fourth break everything?

Posted on 2003-02-24
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Last Modified: 2010-03-18
I have a Redhat 7.1 linux firewall/router with the latest kernel. It successfully routes internet traffic to my internal LAN and also port forwards to port 80 to my DMZ windows 2000 webserver. So I have three fully working Network Cards.

My problem is, I add an extra card, becuase I want to create another separate DMZ, and none of my ADSL connections work, nothing routes properly etc.

It's like, as soon as I stick an extra card in, everything changes: eth0 becomes eth1, eth2 becomes, eth3 (for example)! Why does all this shuffling occur?

Thankyou in advance!


 
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Question by:nathanheathdavies
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17 Comments
 
LVL 6

Expert Comment

by:mbarbos
ID: 8012588
Because the order the NICs are named depends on the type of the NICs (the order the kernel tests for the devices or the order modules are loaded) and also of the position of the NICs in the slots
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LVL 9

Expert Comment

by:majorwoo
ID: 8013065
edit your /etc/modules.conf file after you add the device and put it back the way it was (or if you put the new NIC in the PCI slot furthest from the AGP slot it will probably pick it up last)

alias eth0 eepro100
alias eth1 3c59x
alias eth2 3c59x

if your /etc/modules.conf looked like that before, just make sure the new device gets set to eth3

alias eth0 eepro100
alias eth1 3c59x
alias eth2 3c59x
alias eth3 new_module

instead of
alias eth0 new_module
alias eth1 eepro100
alias eth2 3c59x
alias eth3 3c59x
0
 

Author Comment

by:nathanheathdavies
ID: 8020171
But what if all of my cards are the same, so I get all the same device names, how is one meant to tell the difference between them. I just whish there was a way to know exactly which card was which.
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LVL 6

Expert Comment

by:mbarbos
ID: 8020761
The difference is in the way they are discovered, which has something to do with the slots they are in.
If the cards are all of the same kind, then just simply change the patch cords to suit the new cofiguration. You can also change the slots and find out what is the order in which your PCI slots are discovered (it also depends on the BIOS settings, but you can not always set the interrupts and address routing for the PCI slots) and then install the cards so that a new card will get the next eth number, not one already used.
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LVL 6

Expert Comment

by:mbarbos
ID: 8020778
Oh, you don't get the same device name for 2 different cards, no matter if thea are of the same kind or not (unless you have areally broken kernel/modules).
0
 

Author Comment

by:nathanheathdavies
ID: 8020910
Sorry, I meant the name of the module bit after the:

alias eth2 module
              ^_____________here
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Author Comment

by:nathanheathdavies
ID: 8020919
please ignore where the formatting of the previous post positioned my arrow diagram! I mean, the 'module' name. :)
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Author Comment

by:nathanheathdavies
ID: 8021099
please ignore where the formatting of the previous post positioned my arrow diagram! I mean, the 'module' name. :)
0
 

Author Comment

by:nathanheathdavies
ID: 8021104
please ignore where the formatting of the previous post positioned my arrow diagram! I mean, the 'module' name. :)
0
 
LVL 9

Expert Comment

by:majorwoo
ID: 8021112
if you place this card at the bottom of the PCI slot stack (as far from the AGP as possible) it should be detected last.
0
 
LVL 9

Expert Comment

by:majorwoo
ID: 8021132
exactly what card is it? what module are you using? In some cases you can specify an options line to the card to setup which card uses which
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LVL 6

Expert Comment

by:mbarbos
ID: 8021133
The "module" is the name of the driver that for that card. You get after that some "ethx" interfaces. the "x" is given by the phisical position of the card. I the cards need different modules (drivers) the will get the x first by the order the drivers are loaded and than by the positio in the machine. The order is deterministic, so all you have to do is to see which phisical card gets which name.
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LVL 6

Expert Comment

by:mbarbos
ID: 8021183
Not necessarily, majorwoo. PCI is almost fully mapable (I'm not a natve english speaker, forgive my spelling and the rest). IMHO the best way (still) is to move patch cords around :)
0
 
LVL 9

Expert Comment

by:majorwoo
ID: 8021285
moving the cords is the quick and dirty solution ;-) (and yes its what I did when i added another card to my machine)

but if he really wants to do it another way, i promise at some point in the script we can hack it up to do it his way

;-)

(english looked good to me!)
0
 

Author Comment

by:nathanheathdavies
ID: 8021414
I might try physically removing every card from the machine. I will then boot and remove all configurations, then reboot and add all of the cards again. I will boot up and configure the cards through the kudzu configurator (or just provide the network-scripts file) and maybe my machine can stop suffering from psycosis. Then I will try moving my cords around, trying every possible combination.
If it doesn't work then, I will kill myself.
Can I give both of you points? I have gained excellent ideas out of both of you.
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LVL 9

Expert Comment

by:majorwoo
ID: 8021438
got this out of community support:

1) How to split points -> Ask Moderator assistance in Community Support with a zero point question and the question link (include whom you wish to award what point values).  If the original question value is OK as is, award one expert in the primary question directly, and post a new one in that same topic area, for the other expert(s) you wish to award.  Here's how
  a)  Title = Points for __expertname)__
  b)  Comments = Paste the link (URL) to the primary question for which points are being given.
  c)  Expert then responds and you accept that response to grade and close it.
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Accepted Solution

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majorwoo earned 300 total points
ID: 8021447
but back to the problem...

you can just add the new card, and configure the scripts yourself you dont need to remove them all (but if you do your right, kudzu will sort out most of it for you)

(just add them all at once so you dont have the same problem again)
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