Network Card Strangeness

[Leonard Isham]

On Fri, 22 Oct 2004 16:25:12 +0100 (BST), Jonathan Allen
<jonathan at barumtrading.co.uk> wrote:
> All,
> 
> I have four network cards in an FC2 machine.  This machine is supposed
> to act as a system router between different segments of a LAN, some of
> which is Windows, most of which is Linux, some 10baseT and some 100baseT:
> 
>    eth0: NC100 Network Everywhere Fast Ethernet 10/100 -- a PCI card
>          Manuf: Linksys    Driver: tulip
> 
>    eth1: NC100 Network Everywhere Fast Ethernet 10/100 -- a PCI card
>          Manuf: Linksys    Driver: tulip
> 
>    eth2: NC100 Network Everywhere Fast Ethernet 10/100 -- a PCI card
>          Manuf: Linksys    Driver: tulip
> 
>    eth3: 3c940 10/100/1000Base-T [Marvell]             -- on motherboard
>          Manuf: 3Com Corp  Driver: sk98lin
> 
> In the System Services->Network control panel, all three devices appear
> and can be activated.  They then stay active until reboot or network
> restart, but I can't seem to get a 'ping' to work through eth1 or eth2
> even if I use 'route' to make them the default.  'ifconfig' shows them
> all present with their (different or same, it doesn't seem to make any
> difference) IP addresses and 'route' shows almost the correct segment
> routing, except that they all have 192.168.1.0 on them which I don't
> want.
> 
> Regardless of the active/inactive state in the control panel, on boot or
> network restart, only eth0 and eth3 are started.  Why is this ?
> 
> I am trying to get to:
> 
>    eth0: host IP 192.168.1.64, route: default
>    eth1: host IP 192.168.1.64, route: 192.168.1.63 only
>    eth2: host IP 192.168.1.64, route: 192.168.1.32 only
>    eth3: host IP 192.168.1.64, route: 192.168.1.100 only
> 
> Any ideas how can I get there ?
> 
> Jonathan

You can't get there from here.  What you are attempting to do is a
violation of basic TCP/IP networking principals.

Unless you are "merging" the network cards into one virtual card for
load balancing or redundancy they can't have the same IP address.

A router routes between different subnets and the subnets can't overlap.

-- 
Leonard Isham, CISSP 
Ostendo non ostento.