Re: Need TCP-IP guru advice - 2 networks, 1 firewall

Hello Jim,

You wrote:
>I checked, and the datagram forwarding is alreadty set on.  I still can't 
>ping the firewall from a PC on the other network.  Now what?

That indicates that the AS/400 should be forwarding data from the 172.22 
network to the 172.24 network. However, something is stopping the return 
traffic. Further something in the 172.24 network is stopping traffic for the 
172.22 network from reaching the AS/400. Since you say neither network can PING 
the other the problem is probably due to an incorrect route.

You also wrote:
>>>>>>>
Topology looks something like this:

----------
|        |
| AS/400 | TR Card 1 (172.24.1.1) --> PC's -->  Firewall (172.24.1.10) --> More 
PCs
|        |
|        | TR card 2 (172.22.1.1) --> PC's (172.22.***.***)
----------

It seems rather odd  to have a firewall between PC's on the same network so I 
presume the "More PC's" are really on yet another network.

It is likely that the PC's in the 172.24 network have a default route that 
sends all traffic to the firewall but the firewall doesn't know what to do with 
it so it sends it to its default route which is who-knows-where. In this case 
you need to either:

        1/ add a network route to each PC in the 172.24 network telling it to 
           forward all traffic for the 172.22 network to the 172.24.1.1 
           interface.
--or--
        2/ add a network route to the firewall telling it to forward all 
           traffic for the 172.22 network to the 172.24.1.1 interface.

Something like:
        route add net 172.22.0.0  172.24.1.1  1 netmask 255.255.0.0

should work. Note that each TCP stack has a slightly different syntax for the 
route command so check your OS's help text for the correct syntax.

Regards,
Simon Coulter.
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