topic Re: Mac Address? in Operating System - Linux

Mac Address?

mw_4 — Thu, 13 Mar 2003 01:35:58 GMT

Hi all

I've been getting good helps from you ^^

I have Linux redhat 2.2.14-5.0
The linux system has 2 interface cards, eth0, eth1
but when I type ifconfig -a on system

its output like attached file
but
I am not able to understand why the Mac address are same
HWaddr 08:00:20:B8:C2:ED ,though physcal interfaces are totally different

but it seems like that functions are normal

can you give the why Mac addresses are same and How they are corrected

I think it should be solved
System have been generating messages like

messages:Mar 13 09:11:10 redhat kernel: eth0: HAPPY MEAL (PCI/CheerIO) 10/100BaseT Ethernet 08:00:20:b8:c2:ed
messages:Mar 13 09:11:10 redhat kernel: eth1: HAPPY MEAL (PCI/CheerIO) 10/100BaseT Ethernet 08:00:20:b8:c2:ed
messages:Mar 13 09:11:10 redhat kernel: eth0: Link is up using internal transceiver at 100Mb/s, Full Duplex.
messages:Mar 13 09:11:10 redhat kernel: eth1: Link is up using internal transceiver at 100Mb/s, Half Duplex.

and this morning system are hung for a while...without any messages.
It had happened several times.

Re: Mac Address?

Stuart Browne — Thu, 13 Mar 2003 02:15:05 GMT

A few details from you, if you could..

What distribution of Linux are you using?

What version of 'ifconfig' are you using? ('ifconfig --version')

What type of network cards are they? (using 'lsmod', or viewing '/etc/conf.modules' (or '/etc/modules.conf', depending on the age of the 'modutils' binaries) should get the driver names).

On a number of different machines I have around the place with distributions around the same time period, none of them exhibit this behaviour.

If they are the 'cheap' card from the shop-down-the-road, then it is entirely possible that the two cards do actually have the same MAC adderss (seen this once before!). But they would have to be identical cards.

Re: Mac Address?

Josh Owings — Thu, 13 Mar 2003 19:32:22 GMT

I am going to go out on a limb and guess that he is using redhat. (maybe 6.1)

===============================
messages:Mar 13 09:11:10 redhat kernel: eth0: HAPPY MEAL (PCI/CheerIO) 10/100BaseT Ethernet 08:00:20:b8:c2:ed
===============================

Re: Mac Address?

Tony Contratto — Thu, 13 Mar 2003 23:18:24 GMT

Hi all,

The "Happy Meal" card is a Sun Microsystems NIC. Is this by chance one of the 4 port cards?

IIRC, it has been awhile since I've messed with a Sun box. All ethernet interfaces, by default, have the same MAC address on a Sun box. The driver gets the MAC from the PROM in the system and ignores the address on the card. At least that's how it works with Solaris, I'm not sure what happens with the Linux drivers.

--
Tony

BTW, The first 3 octets of the MAC address are the vendor ID.
08:00:20 = Sun Microsystems Inc.

Re: Mac Address?

Stuart Browne — Fri, 14 Mar 2003 02:33:26 GMT

Anthony,

Do you know of an online list of Vendor ID's? I can think of far too many situations where it would be helpful to know.

Re: Mac Address?

Stuart Browne — Fri, 14 Mar 2003 02:35:20 GMT

Actually, don't worry..

Silly me should have done 10second search first, then asked..

http://standards.ieee.org/regauth/oui/oui.txt

*whee!*

Re: Mac Address?

mw_4 — Fri, 14 Mar 2003 02:48:27 GMT

actually
I intalled redhat on sun ultra60 system

Re: Mac Address?

Stuart Browne — Fri, 14 Mar 2003 03:01:17 GMT

That beign the case, Anthony's response seems the most accurate.

As to how to get the kernel to look at the card instead of the PROM, I don't know. Unless an Updated kernel fixes this, I'm unaware of another way to fix the issue.

Re: Mac Address?

Tony Contratto — Fri, 14 Mar 2003 05:54:33 GMT

Are both of the interfaces attached to the same physical network/broadcast domain?

If the interfaces are NOT attached to the same physical network, both of them having the same MAC address should not be causing any problems.

Stuart,
Here is a lookup site I found with a quick google search:

http://coffer.com/mac_find/

--
Tony