2 NICs on same subnet

[Thalionath]

Hi all

I have a gentoo box, which is connected with 2 network cards to the same subnet.

eth0 192.168.1.10/24
eth1 192.168.1.11/24

Yesterday, I finally decided to update my /etc/conf.d/net

from the old syntax:

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iface_eth0="192.168.1.10 broadcast 192.168.1.255 netmask 255.255.255.0"
iface_eth1="192.168.1.11 broadcast 192.168.1.255 netmask 255.255.255.0"
gateway="eth0/192.168.1.1"

(has been working for 2 years)

to the new syntax:

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config_eth0=( "192.168.1.10/24 brd 192.168.1.255" )
routes_eth0=( "default via 192.168.1.1" )

config_eth1=( "192.168.1.11/24 brd 192.168.1.255" )
routes_eth1=( "default via 192.168.1.1" )

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Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.1  *               255.255.255.0 U     0      0        0 eth0
192.168.1.1  *               255.255.255.0 U     0      0        0 eth1
loopback        *               255.0.0.0       U     0      0        0 lo
default         192.168.1.1  0.0.0.0         UG    0      0        0 eth1
default         192.168.1.1  0.0.0.0         UG    0      0        0 eth0

Now I've the problem, that only one of the two works at a time.

It seams somehow logically to me, that only one can be working with 2 default gateways in the routing table. But why and how worked it with the old
config?

Would it make more sense to bond the interfaces together?

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slaves_bond0="eth0 eth1"

config_bond0=( "192.168.1.10/24 brd 192.168.1.255" "192.168.1.11/24 brd 192.168.1.255" )
routes_bond0=( "default via 192.168.1.1" )

thx

[ttuegel]

Yes, you'll want to bond the interfaces since they're on the same subnet. That will give you the result you're looking for.

[HeissFuss]

Is there a reason you're using 2 NICs on the same subnet instead of a virtual interface?

[Thalionath]

@ttuegel thx

@HeissFuss: No. I'll bond the interfaces together as soon I get access to the box...

[Assgier]

Should the bond not work; when comparing your old config against your current one, note that in your old config you only specify a gateway for eth0 while, in your current one, you specify the same gateway for both NIC's. It could be the issue

[Cyker]

Yeah; In the original config eth0 is the only one with a default gateway, but in the new config you gave both eth0 and eth1 the gateway.
I think that's why one of them gets disabled - To avoid creating a loop (And thus a Happy Fun Packet Storm!(tm))

Just delete the routes_eth1=( "default via 192.168.1.1" ) line...