Subject: Re: Uncommon routing arrangement
To: John Klos <>
From: Daniel Carosone <>
List: tech-net
Date: 02/17/2005 07:58:27
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On Thu, Feb 17, 2005 at 07:34:39AM +1100, Daniel Carosone wrote:
> Either way, ipf fastroute is probably the best way to direct traffic
> outbound

Note also that while both links *ought* to use the same IP address as
their default route, they don't actually have to use that address in
their routing tables. This address doesn't appear in the packets, it's
only used to find the link-layer next hop address.  So you could make
up a fake router address and add a static arp entry for that address
on the relevant nic, and not use overlapping subnets at all.

Beware, however, that the router is hopefully/probably actually also a
failover pair, and its not infeasible that the MAC address could
change when the ISP does its own failover.

> but the answer will have important implications for
> interaction with failover.=20

To clarify: bridge(4) will help with failover, but unless you're very
careful, could hinder load balancing.  If the head end does link
selection by IP address, you won't be able to failover those IP
addresses, either.


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