I have two NICs on a linux box running hardhat 2.4.2 kernel.
The output of ifconfig:
eth0 Link encap:Ethernet HWaddr 00:30:48:11:31:E8
inet addr:10.8.1.26 Bcast:10.8.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
...
eth1 Link encap:Ethernet HWaddr 00:30:48:11:31:18
inet addr:10.8.1.49 Bcast:10.8.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
....

Everything seems to be fine, I can ping both interfaces...however,
running arp shows that both interfaces bind to the SAME MAC -- the one that was brought up first. In fact, even when the cable is not connected to the second (up later) NIC, I can still ping its IP address, while the packet actually go to the first NIC.

Is it possibly to bind different IP addresses to different MACs for linux box with multiple NICs at all (and the IPs are within the same subnet)?

I know for a fact that lynxOS does allow this. Is this a feature of OS or driver?

look at

http://www.linuxquestions.org/questi...?threadid=6493

If you get it working seemlessly, i'd be interested in ho0w you make it possible to ping between two machiens conenced to each interface.

Both eth0 and eth1 are connected to a netgear switch. I was able to ping both from another machine connnected to the same switch.

It is also true that if I put eth0 and eth1 on different subnet, the MAC binding would be fine. The problem arises when they are on the same subnet.

Below is the output of route:

Destination Gateway Genmask Flags Metric Ref Use Iface
10.8.1.0 * 255.255.255.0 U 0 0 0 eth0
10.8.1.0 * 255.255.255.0 U 0 0 0 eth1
default 10.8.1.1 0.0.0.0 UG 0 0 0 eth0

Hi..

I think it is not possible to configure two ethernet cards on a same subnet.
Better u can try channelbonding method.


What is ur requirment.

More Datatransfer ???

etc//
siddiqu.T

The reason we want to use two NICs: we have logically two pathes to the linux boxes: one for critical control data (cannot be delayed), another one for large transfer bandwidth, but not worried about the timing. It seems using two seperate NICs (which are already present on the motherboard) for the two traffic is probably a good idea.

Of course we could setup two subnets, but it is more of a hassle if we could do it within the same subnet.

We were able to do this when we were using lynxOS RTOS. Now linux does not seem to support this....

OK, i've been given a bit more info on this just now...

You can split a subnet into parts by specifying an appropriate netmask. in your /etc/sysconfig/network-scripts/ifcfg-ethX files try changing the netmask thus...

NETMASK=255.255.255.128
rather than
NETMASK=255.255.255.0

and assign proper IP addresses to each NIC, one below X.X.X.128, and one above.

I've got this far, and it seems to work, as i can ping either interface from one remote machine. I only have one remote machine available to me at the moment, so don't know if this is actually worknig correctly or not...

I've got a nasty feeling that this is basically the same as having them on different subnets tho (or rather IS having them on two different subnets still, but hiding that fact...)

if you think this is worth a go, please tell me what you get. There's also the very strong possibilty that it won't work, as i can certainly see why it won't... please let me know if i'm talking total arse| ;-)

Just as a followup:

acid_kewpie, your "nasty feeling" is on the mark. Check out this site for a good (although slightly brain-bending) elaboration on the whole subject.

Hye..

Why dont u try channel bonding. U can aggreate multilbe cards
and logically it will work as a single card


Linux clusters they are using this
siddiqu.T

I've found a few discussions regarding multiple NICs on the same subnet from linux kernel discussion list:
http://www.uwsg.indiana.edu/hypermai...02.1/1038.html

http://www.uwsg.indiana.edu/hypermai...09.0/0244.html

Except for using different subnet, there seems to be no workaround. Many other OS behave differently. Linux is just the odd ball.

I have mine on different subnets, samba wins server lets clients cross subnets to access each other.