enumeration order of eth interfaces

Hi all,

Hopefully a quick question for you. Please tell me if this is the wrong
newsgroup for such a question.

I have a 2.4 system (RH8) with three ethernet interfaces, eth0, 1, 2. When
I upgrade this box to use the 2.6 kernel, the order of these interfaces
changes (physically, eth0 becomes eth2, and vice versa).

This only happens on particular hardware - other boxes do not have this
issue.

Any odea what's going on?

Thanks in advance,
Doug

>
> I have a 2.4 system (RH8) with three ethernet interfaces, eth0, 1, 2.
> When I upgrade this box to use the 2.6 kernel, the order of these
> interfaces changes (physically, eth0 becomes eth2, and vice versa).
>
> This only happens on particular hardware - other boxes do not have this
> issue.
>
> Any odea what's going on?

No, but if it's important for you to be able to definitely refer to a
certain interface by a certain name, you can use nameif or ifrename to
assign arbitrary names to interfaces with given attribuates, e.g. MACs.
I've used both and find ifrename to be a little more flexible, and also
IIRC hotplug will call it (and not nameif) when the interface comes up to
rename it automatically.

--
To reply by email, change "deadspam.com" to "alumni.utexas.net"

On Mon, 30 May 2005 10:12:01 GMT, doug wrote:
> Hi all,
>
> Hopefully a quick question for you. Please tell me if this is the wrong
> newsgroup for such a question.
>
> I have a 2.4 system (RH8) with three ethernet interfaces, eth0, 1, 2. When
> I upgrade this box to use the 2.6 kernel, the order of these interfaces
> changes (physically, eth0 becomes eth2, and vice versa).

As I misunderstand it, they are numbered in the order they are found
on the buss when the kernel probes it.

>
> This only happens on particular hardware - other boxes do not have this
> issue.
>
> Any odea what's going on?

Guessing Plug-N-Play is not set NO/OFF/FALSE in the pc's bios.

"Bit Twister" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Mon, 30 May 2005 10:12:01 GMT, doug wrote:
>> Hi all,
>>
>> Hopefully a quick question for you. Please tell me if this is the wrong
>> newsgroup for such a question.
>>
>> I have a 2.4 system (RH8) with three ethernet interfaces, eth0, 1, 2.
>> When
>> I upgrade this box to use the 2.6 kernel, the order of these interfaces
>> changes (physically, eth0 becomes eth2, and vice versa).
>
> As I misunderstand it, they are numbered in the order they are found
> on the buss when the kernel probes it.

Yeah, that's what I thought, but why is this order switched on 2.6 on
certain machines (i.e. what's so special about *this* hardware?) And is
there any way to specify this order myself?

>
>>
>> This only happens on particular hardware - other boxes do not have this
>> issue.
>>
>> Any odea what's going on?
>
> Guessing Plug-N-Play is not set NO/OFF/FALSE in the pc's bios.

I wonder if it could be that simple! I'll have a check tomorrow. Thx!

Doug

"Andrew Schulman" <(E-Mail Removed)> wrote in message
news:UbEme.42932$(E-Mail Removed). ..
>>
>> I have a 2.4 system (RH8) with three ethernet interfaces, eth0, 1, 2.
>> When I upgrade this box to use the 2.6 kernel, the order of these
>> interfaces changes (physically, eth0 becomes eth2, and vice versa).
>>
>> This only happens on particular hardware - other boxes do not have this
>> issue.
>>
>> Any odea what's going on?
>
> No, but if it's important for you to be able to definitely refer to a
> certain interface by a certain name, you can use nameif or ifrename to
> assign arbitrary names to interfaces with given attribuates, e.g. MACs.
> I've used both and find ifrename to be a little more flexible, and also
> IIRC hotplug will call it (and not nameif) when the interface comes up to
> rename it automatically.
>
> --
> To reply by email, change "deadspam.com" to "alumni.utexas.net"
>

Wierd, didn't see your post 'till now.

Thanks though. I'll have a look and let you know!

Ta,
Doug

> Yeah, that's what I thought, but why is this order switched on 2.6 on
> certain machines (i.e. what's so special about *this* hardware?) And is
> there any way to specify this order myself?
More detail needed - do all three interfaces use the same driver? (I'm
guessing yes, since otherwise the module mapping suffices to fix the order.)

On Mon, 30 May 2005 23:28:08 -0400, Allen McIntosh wrote:
>
>> Yeah, that's what I thought, but why is this order switched on 2.6 on
>> certain machines (i.e. what's so special about *this* hardware?) And is
>> there any way to specify this order myself?
> More detail needed - do all three interfaces use the same driver? (I'm
> guessing yes, since otherwise the module mapping suffices to fix the order.)

Another suggestion is to check the boot loader config files to see
if the Advanced Programmable Interrupt Controller (APIC) setting is different.

"Allen McIntosh" <(E-Mail Removed)> wrote in message
news:cRQme.3847$(E-Mail Removed)...
>
>> Yeah, that's what I thought, but why is this order switched on 2.6 on
>> certain machines (i.e. what's so special about *this* hardware?) And is
>> there any way to specify this order myself?
> More detail needed - do all three interfaces use the same driver? (I'm
> guessing yes, since otherwise the module mapping suffices to fix the
> order.)

Sorry:
In 2.4, eth0 and eth1 are gigabit ethernet drivers (e1000), and eth2 is an
eepro100.
After I install the 2.6 kernel and reboot, the machine won't get on the
network until:
- I swap the aliases for eth0 and eth2 in /etc/modprobe.conf
- I swap (and massage, a little) the ifcfg-eth0 and -the2 network-script
files

Ta,
Doug

> In 2.4, eth0 and eth1 are gigabit ethernet drivers (e1000), and eth2 is an
> eepro100.
> After I install the 2.6 kernel and reboot, the machine won't get on the
> network until:
> - I swap the aliases for eth0 and eth2 in /etc/modprobe.conf
> - I swap (and massage, a little) the ifcfg-eth0 and -the2 network-script
> files

Is the statement "the 2.6 kernel discovers the two e1000 cards in the
opposite order" consistent with your facts? Look really carefully at
boot messages (iirc they contain the MAC address). I haven't used 2.6
enough to have a clue why this should be so. I have machines with
similar hardware, so I expect I'll have to figure it out eventually.

"Allen McIntosh" <(E-Mail Removed)> wrote in message
news:JRZme.1736$(E-Mail Removed)...
>> In 2.4, eth0 and eth1 are gigabit ethernet drivers (e1000), and eth2 is
>> an eepro100.
>> After I install the 2.6 kernel and reboot, the machine won't get on the
>> network until:
>> - I swap the aliases for eth0 and eth2 in /etc/modprobe.conf
>> - I swap (and massage, a little) the ifcfg-eth0 and -the2 network-script
>> files
>
> Is the statement "the 2.6 kernel discovers the two e1000 cards in the
> opposite order" consistent with your facts? Look really carefully at boot
> messages (iirc they contain the MAC address). I haven't used 2.6 enough
> to have a clue why this should be so. I have machines with similar
> hardware, so I expect I'll have to figure it out eventually.

Yeah. Let's call the adapters G1, G2 and M3 (for the two gigabyte ports,
and the one 10/100 port).

On 2.4, on a particular set of hardware, we get this mapping:
- G1 is bound to eth0
- G2 is bound to eth1
- M3 is bound to eth2

On 2.6, *on this partuclar hardware only*, we get:
- M3 is bound to eth0
- G2 is bound to eth1
- G1 is bound to eth2

And the only reason I can find for this happening so far is to piss me off!

Doug