could two gateway exist in the same subnet

[George Liu_2]

I have a problem to set a 2nd gateway to a dedicated network. Here is the background:

There was a default gw 1.1.1.1 for network 1.1.1.0/24,
Second gw 1.1.1.2 was later added to 192.168.0.0/24,
In the 1.1.1.0 network, 1.1.1.3 is HPUX, and 1.1.1.4 is Linux.

On 1.1.1.3, pings to 192.168.0.1 got response before added the second GW.
It didn't get response after adding the second GW.
It worked again after deleted the second GW.
The routing table showed the situation.

On Linux 1.1.1.4. Pings always get response from 192.168.0.1.

Any idea?

[harry d brown jr]

WOW.

Could you tell us what the ROUTING was on 1.1.1.3??

Either 1.1.1.3 has to have a rule stating that 1.1.1.2 is the GW to 192.168 or 1.1.1.1 has to route to 1.1.1.2 for 192.168 traffic.

live free or die
harry

[Ron Kinner]

I wonder if you are running into HP 11.0's wonderful dead gateway detection problem. They cleverly have the PC ping the gateway to see if it is alive and if no response declare the gateway dead and stop using it. They added this just as most routers for security reasons are having filters added to keep them from replying to pings and made it the default. See if you can ping the 1.1.1.2. Bet you can't and that you are using 11.0 or newer.

Fix is to set
ip_ire_gw_probe_interval
to 0 using ndd.

If that is not the case then I suggest you try a
traceroute 192.168.0.1
on each machine before adding your gateway.

Go to 192.168.0.1 and run a traceroute back to each machine to see what the reply path is.

Repeat both tests after adding the gateway.

Make sure that the Linux box is talking to the same PC in both cases and that there are no filters on the routers which might block one and not the other. Check that your masks are as you think they should be.

Ron

[George Liu_2]

It's HPUX 10.20,

and traceroute was blanked at 192.168.0. side because of the routers setting.




Thanks.

[Ron Kinner]

Could we see
netstat -rn
and
netstat -r
on the HP with the 2nd gateway added?

Make sure that if you used the gateway's name in your route statement that you have the correct name/ip pair in /etc/hosts.

Ron