How to Set/Get UUID for a NIC -> real life

Reindl Harald h.reindl at thelounge.net
Sat Jan 12 15:33:22 UTC 2013



Am 12.01.2013 14:23, schrieb Reindl Harald:
> 
> 
> Am 12.01.2013 12:01, schrieb Tim:
>> Allegedly, on or about 11 January 2013, Alan Cox sent:
>>> The MAC has to be *host* unique not port unique. Thus some old SPARC
>>> boxes have one Mac for all the ports. Many Ethernet bridges also do
>>> the same trick.
>>
>> I would have thought they'd need to be LAN unique, since the MAC is used
>> for communication between the right NICs on a LAN.  How's that going to
>> work when they're not unique.
> 
> google for NIC bonding / teaming
> http://www.linuxhorizon.ro/bonding.html
> 
> it IS unique for the LAN but not for the machine
> that is why failover can work as it works
> 
> it would be only a problem if DIFFERENT MACHINES have he
> same MAC because it is used fro cummunication and so it would
> be random who get which packages but with bondig it does not
> matter on which NIC packets are coming in and going out because
> it is the target of bonding using more than one NIC and with
> round-robin you even use all the NICs at the same time and not
> only for failover

and here the real world of bonding because i have yet wol-booted
my remote-workstation for other reasons

as you can see the first 3 interfaces have the same MAC
bond0 is the relevant, br0 only get the MAX from the interface behind

both have the MAC from eth0
eth1 has it's own because "Bonding Mode: adaptive load balancing"
____________________________________________________________

bond0: flags=5443<UP,BROADCAST,RUNNING,PROMISC,MASTER,MULTICAST>  mtu 1472
        ether 78:ac:c0:b1:76:e4  txqueuelen 0  (Ethernet)
        RX packets 1075  bytes 148294 (144.8 KiB)
        RX errors 0  dropped 101  overruns 0  frame 0
        TX packets 1917  bytes 174680 (170.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1472
        inet 10.0.0.99  netmask 255.255.255.0  broadcast 10.0.0.255
        ether 78:ac:c0:b1:76:e4  txqueuelen 0  (Ethernet)
        RX packets 969  bytes 122332 (119.4 KiB)
        RX errors 0  dropped 56  overruns 0  frame 0
        TX packets 401  bytes 75484 (73.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1472
        ether 78:ac:c0:b1:76:e4  txqueuelen 1000  (Ethernet)
        RX packets 981  bytes 142218 (138.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1104  bytes 121274 (118.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 20  memory 0xfe700000-fe720000

eth1: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1472
        ether 00:1b:21:b6:5f:28  txqueuelen 1000  (Ethernet)
        RX packets 94  bytes 6076 (5.9 KiB)
        RX errors 0  dropped 92  overruns 0  frame 0
        TX packets 813  bytes 53406 (52.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16  memory 0xfe6c0000-fe6e0000
____________________________________________________________

after "ifdown eth0" you even see "eth1" with the previously
used MAc of eth0 and that is why the failover works without
interrupt connections

Jan 12 16:27:39 rh kernel: bonding: bond0: releasing active interface eth0
Jan 12 16:27:39 rh kernel: device eth0 left promiscuous mode
Jan 12 16:27:39 rh kernel: bonding: bond0: making interface eth1 the new active one.
Jan 12 16:27:39 rh kernel: device eth1 entered promiscuous mode

bond0: flags=5443<UP,BROADCAST,RUNNING,PROMISC,MASTER,MULTICAST>  mtu 1472
        ether 78:ac:c0:b1:76:e4  txqueuelen 0  (Ethernet)
        RX packets 226  bytes 15692 (15.3 KiB)
        RX errors 0  dropped 214  overruns 0  frame 0
        TX packets 1661  bytes 108084 (105.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1472
        inet 10.0.0.99  netmask 255.255.255.0  broadcast 10.0.0.255
        ether 78:ac:c0:b1:76:e4  txqueuelen 0  (Ethernet)
        RX packets 1543  bytes 170980 (166.9 KiB)
        RX errors 0  dropped 117  overruns 0  frame 0
        TX packets 528  bytes 84906 (82.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth1: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1472
        ether 78:ac:c0:b1:76:e4  txqueuelen 1000  (Ethernet)
        RX packets 226  bytes 15692 (15.3 KiB)
        RX errors 0  dropped 197  overruns 0  frame 0
        TX packets 1668  bytes 108890 (106.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16  memory 0xfe6c0000-fe6e0000
____________________________________________________________

after "ifup eth0" again you see even "eth0" becomes the MAC
from the physical "eth1" because they active interface does
not change now without a good reason and "additional NIC" is
no good reason, from the view of the LAN the machine has all
the time "78:ac:c0:b1:76:e4"

bond0: flags=5443<UP,BROADCAST,RUNNING,PROMISC,MASTER,MULTICAST>  mtu 1472
        ether 78:ac:c0:b1:76:e4  txqueuelen 0  (Ethernet)
        RX packets 2435  bytes 448660 (438.1 KiB)
        RX errors 0  dropped 214  overruns 0  frame 0
        TX packets 4471  bytes 387055 (377.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1472
        inet 10.0.0.99  netmask 255.255.255.0  broadcast 10.0.0.255
        ether 78:ac:c0:b1:76:e4  txqueuelen 0  (Ethernet)
        RX packets 2124  bytes 385770 (376.7 KiB)
        RX errors 0  dropped 162  overruns 0  frame 0
        TX packets 752  bytes 144243 (140.8 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0: flags=6147<UP,BROADCAST,SLAVE,MULTICAST>  mtu 1472
        ether 00:1b:21:b6:5f:28  txqueuelen 1000  (Ethernet)
        RX packets 1547  bytes 201658 (196.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1971  bytes 178638 (174.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 20  memory 0xfe700000-fe720000

eth1: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1472
        ether 78:ac:c0:b1:76:e4  txqueuelen 1000  (Ethernet)
        RX packets 888  bytes 247002 (241.2 KiB)
        RX errors 0  dropped 197  overruns 0  frame 0
        TX packets 2507  bytes 209255 (204.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16  memory 0xfe6c0000-fe6e0000

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