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Re: Linux box


On Wed, Jul 31, 2002 at 09:15:53PM +0200, Riccardo Losselli wrote:
> I know it will never be like bgp, but it still better than nothing at
> all, or not?

I don't know bgp at all, but I cannot believe it's easier than the

One Linux Router, three network cards:

1- nothing stops you, if you have two or more IP-segments on the
   same physical network. - connect net1 and net2 either directly or
   via a switch, or whatever.

2- Use some old unuseful box and plug three NIC into it:
   eth0 to the joint networks 1 & 2
   eth1 to link 1
   eth2 to link 2

3- give eth0 two IP numbers, one as gateway in net1 and one as gateway
   in net 2

4- route net2 to  ipalias1 and net1 to ipalias2 on the linux box.

5- use other recomendations (policy and metrics) to route default
   packets to eth1 and eth2 respectively.

6- Internet Mail has it's own "failover" mecanism.  Put a
   "proxy"-mailserver on net1 and the "real" mailserver on net2,
   declare mx1 with priority 20 and mx2 with priority 10 for net2 in
   the DNS - Or vice versa. Do the same (or vice versa) for net1.

7- DNS has it's own "failover" mecanism.  Talk to your DNS-superior
   and tell him/her that dns1 (from net1) and dns2 are nameservers for
   net1 and also for net2.

If any of the two links fail, the server in the other "net" takes over
the task.  External clients will occasionally fail, because they try
the higher priority MX first, the lower only when the first is not

DNS-servers for a domain are handed out "arbitrarily" anyway, if one
is not reachable, there is a 50:50 chance a client has to try two
times to get an answer.

Use one server with IP alias for net1 and net2 if you are keen or

Client computers with sensible OS's can route more then one network to
the same NIC, take advantage of this.

Best Regards,


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