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Re: OT: what to do with two T1s?



On Mon, 2 Jul 2001, Derek Sivers wrote:

> #1 - put different services on the two different T1s.   (websites on 
> one.  dns & mail & office web use on the other?)
> or....
> #2 - Somehow MERGE two T1s into "redundancy" using djbdns, ipnat, or 
> something like that?
> 
> Is there a way using our OpenBSD tools (IPNAT?), to have both T1's coming 
> into our OpenBSD router/firewall, then distribute the services from 
> there?   So that if one T1 goes down the other one will take over, and 
> nothing will be down as far as the world can tell?
Yes. The way you do this:
Assuming you have IP range A for first T1 and IP range B for second T1,
you register two nameservers with *nic, one out of range A, one out of
range B. 

 ISP1  ISP2
  \    /
   \  /
    fw
     |
     |
     |
 internal 

Then, configure two instances of djbdns, bind each one to particular
interface, and make them serve entries from different zone files.

Nameserver bound to IP in range A must serve zone which only contains IPs
in range A.

You must have low TTL on all your entries (<30 minutes) as it determines
how fast the failover will be.

Then, using IPnat, map statically ports from both ranges to one internal
range, so internal machines wouldn't need to care where'd packet come
from.

I have this setup at home. Its not bad at all.

-alex