[LARTC] Double Ethernet

[LARTC] Double Ethernet

[Román Reynoso]

        Hi to everyone!

I don't know how the mailing list works but I will try to do it as best
as i could.

I would like to know how can i do one server with two "eth" connected to
the same network 34.0/24, two ip's .23 and .17
answer through the eth/ip they are listening. I have read the split
access example, but I don't know if it ís what i need.

Just making two route tables form the diferent eth/ip is good?

Thanks in advance,

Roman.

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Re: [LARTC] Double Ethernet

[Martin A. Brown]

Román,

 : I would like to know how can i do one server with two "eth" connected
 : to the same network 34.0/24, two ip's .23 and .17 answer through the
 : eth/ip they are listening.

I thought I have answered this question before, but I have been unable to
find the exact answer for you.  Nonetheless, you should be able to do this
without too much trouble.  I'd recommend reading up on several matters.

First, you'll want to see what somebody else is doing to solve a similar
problem [1], and next you'll want to read up on ARP flux [2].  ARP flux
will be a problem for you, since you'll have two connections to the same
broadcast domain.

 : Just making two route tables form the diferent eth/ip is good?

That's not quite complete.  You should probably use ip rule statements
in conjunction with routing tables.  This is not as important as preparing
for the ARP flux problem.

# ip rule from x.y.34.23 table out.eth0
# ip rule from x.y.34.17 table out.eth1

# ip route add x.y.34.0/24 dev eth0 table out.eth0 src x.y.34.23
# ip route add x.y.34.0/24 dev eth1 table out.eth1 src x.y.34.17

The above commands should ensure that packets addressed from each address
are transmitted from each interface (in this example, x.y.34.23 is hosted
on eth0 and x.y.34.17 on eth1).

 : I have read the split access example, but I don't know if it ís what i
 : need.

I don't think split access is what you desire.  You didn't explain much
about your application or need for multiple interfaces, so I'll point out
that depending on your needs, you may find bonding (see
Documentation/networking/bonding.txt in your kernel release) or teql (see
LARTC howto [3]) to match your goals.

-Martin

 [1] http://linux-ip.net/html/ether-arp.html#ether-arp-flux
 [2] http://mailman.ds9a.nl/pipermail/lartc/2003q1/006922.html
 [3] http://lartc.org/howto/

-- 
Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com

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