OSPF route installed when recursed via connected interface

Guys,

This is doing my head in and even if it can't be done - at least I'd
like someone who may have done this enlighten me.

Router A is connected to a /23 network on its fa0/0 interface
Router A has a point to point link to Router B each on their fa0/1
interface
Router B is connected to a /23 network on its fa0/0
Both Router A and Router B are sharing the same /23 space but at
different geographical locations.

So now we add the salt...

Behind each Router and in the /23 space there is a PIX which also has
a /23 mask BUT is authoritative for one of the /24 networks within
the /23 space and 'secondary' for the other /24 within that space.
What I want to do it advertise both of the /24's into OSPF at each PIX
into RTR_A and RTR_B. So I've got a couple of static routes pointing
to the PIX interface for each /24 and then a route-map redistributing
the /24's to the RTR's at each end...job done.

The problem I see is that each of the RTR's receives the /24 networks
from both PIX boxes BUT when the route is added to the routing table
it sees the next hop via the /23 interface fa0/0 NOT the point-to-
point link fa0/1.

Diagramatically we have:

PIX_A <-> fa0/0 RTR_A fa0/1 <-> fa0/1 RTR_B fa0/0 <-> PIX_B
192.168.0.0/23 <-> 192.168.255.0/30 <-> 192.168.0.0/23

PIX_A has IP address 192.168.0.254/23
PIX_B has IP address 192.168.1.254/23
RTR_A has IP address 192.168.0 1/23
RTR_B has IP address 192.168.1.1/23

PIX_A is advertising networks 192.168.0.0/24 and 192.168.1.0/24 with
metric added to the 192.168.1.0/24 network
PIX_B is advertising networks 192.168.0.0/24 and 192.168.1.0/24 with
metric added to the 192.168.0.0/24 network

The routing table for RTR_A sees the 192.168.1.0 /24 via interface fa0/0
The routing table for RTR_B sees the 192.168.0.0 /24 via interface fa0/0

The outcome is that the routes are in the table which is great but
that the next hop is via the wrong interface. How can we get OSPF to
install the route so that it goes via the fa0/1 interface and not do a
recursive lookup and send it out the connected fa0/0 interface?

Cheers Gurus
Rich

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Received on Fri Oct 02 2009 - 14:52:16 ART