Hi....

On Mon, Jan 16, 2012 at 09:16, hu jun [off-list ref] wrote:

then I unplug eth1 , ethtool eth1 show "Link detected: no",

now on B :ping 192.168.160.11 and 192.168.160.21, both are ok, too.

Maybe the thing that happen is that when you ping eth1 of A from B,
the flow is: B send ICMP--> A' eth0 receives it--> forward it to eth1

Eth1, in my humble opinion, is not really answering "by hardware", but
just it's network stack. Since you made eth0 and eth1 under the same
broadcast address, the effect is like you were doing bonding between
eth0+eth1 in A.

Just curious, are you enabling IP forwarding in A? Or bridging or something?


-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

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