AIX

Hi,

I have a system with network interfaces en0 and en1

en0:
physical ip: 1.1.1.10
virtual ip1: 192.168.100.11
virtual ip2: 192.168.100.12

en1:
physical ip: 1.1.1.20
virtual ip1: 192.168.100.20
virtual ip2: 192.168.100.21

default gateway ist 192.168.100.254

when I open a connection from this host to another host, it's established from ip 192.168.100.11

but I want it to be established from 192.168.100.21 to one special host behind a firewall

the interface name on which the ips reside on may differ, so I need a host route, and specify the source ip, and not the source interface, it would be easy to say take en1 when connecting to host x, but that's not what I want
any ideas?

try smit route so you can add routs from there

it's not possible to add a host route from an ip, it's just possible to specify an interface in the smit menu

on linux, my interface would be eth0:1, eth0:2

but on AIX, there are no additional interfaces created for ip aliasing

I am not sure if i understand you correctly, but wouldn't a simple static route solve your problem? Use "route add -host ..." to add a static route to the destination with a network mask of 255.255.255.255 and your desired local IP address as gateway. You can indeed use an IP address as gateway, can't you?

I hope this helps.

bakunin

In AIX, you can use the -interface option with route.
This line should solve your problem:

route add -host targethost -interface 192.168.100.21

If omitting "-interface", the system would use the primary address on the same interface as gateway, in your case 1.1.1.20, which is not what you want.

No do not use route add with AIX as the route will disappear when you reboot the server. The correct way to this is via smithy tcpip and add static route.

You can do this via the command line with a chdev command on the inter device, but it needs a lot of commas in the right place. You can specify the en device that you want a route to use.

In relation to the original question, the trouble is that the TCP/IP stack can't differentiate between which of the two source addresses that you have as they are in the same subnet. My understanding of TCP/IP tells me that this will lead to ambiguous routing and problems. Would you not be better to create an ether channel with the two intfaces and have a single ip address on it as being easier to manage?

AIX cannot handle multiple adapters, or interfaces, in the same subnet. Why would it?
You need to separate the the addressed in to different subnets if you need to gain control over what goes where.
Or do you have subnet masks one IP address wide?