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Author Topic: MAC address - all for one and one for all  (Read 1904 times)
vkashesh
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« on: April 06, 2010, 08:52:20 AM »

Hi everyone,
I have 3 Plugs and they all have the same HWAddr (or the MAC address).  When I connect them online, they all get the same IP address....  is there something wrong with this? Shouldn't each Ethernet card have its own unique MAC address?  Or am I just misunderstanding the entire process?!?!?!

I try to release and renew the IP but as long as I have one of the three plugs connected to the network, it keep obtaining the same IP and can never change it until I have only 1 connected to the network.... then I connect the second one and it obtains the same new IP and the third does the same....

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fragfutter
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« Reply #1 on: April 06, 2010, 08:58:14 AM »

did you flash them with the installer?

The macaddress is an environment variable of the u-boot. You should be able to modify it there.
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vkashesh
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« Reply #2 on: April 06, 2010, 09:01:07 AM »

Two of them I upgraded and one came already upgraded when I purchased it.

Please correct me if I am wrong, but I thought the MAC address is unique and is assigned by the manufacturer.  If I can change it, then it is not longer a unique value since I can be assigning it an address that some other hardware or device have.

However, can you elaborate on your comments that the mac address is an environment variable of the u-boot?
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birdman
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« Reply #3 on: April 06, 2010, 01:24:00 PM »

Please correct me if I am wrong, but I thought the MAC address is unique and is assigned by the manufacturer.
Correct(ish).  The manufacturer will have assigned a MAC to it. 
Quote
If I can change it, then it is not longer a unique value since I can be assigning it an address that some other hardware or device have.
Then assign one that is not in use on your network (it's only per-network that matters).  You can usually(?) assign MAC addresses to interfaces as that is needed for High Availability switchovers.[/quote]
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However, can you elaborate on your comments that the mac address is an environment variable of the u-boot?
It's also settable in the interface config (which would cure your DHCP issues without needing to get to the boot environment).  Just add a line like this (with a suitable MAC) to the relevant interface sections in /etc/network/interfaces.
Code:
hwaddress ether 00:50:43:01:ff:0d
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tinker
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« Reply #4 on: April 11, 2010, 08:33:19 PM »

The MAC address should be on a label on the bottom side of the plug.  Use that value to set the environment variable in u-boot
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vkashesh
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« Reply #5 on: April 12, 2010, 08:04:20 AM »

Found the label and the MAC address.  I used birdman's suggestion to get the right MAC address set in the plug I have but this will be a temporary fix.

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