Network interface response order

[Brian Lin]

I noticed HP engineer replied regarding APA question 'Two network interfaces load balancing' (January 12, 2001) talking about using ndd to setup ip_strong_es_model to route source and desination through designed interfaces.

Here we have similar problem when application server (Bea WebLogic) binding a license ip. We notice sometime the server response ip is not correct because we config 3 NIC with 4 ip (lan1 and lan2 is apa group and config to 2 ip, which means lan100 and lan100:1) on two machines. I tried to setup ip_strong_es_model to see whether the response is correct when clients make a http requests. By using multicasting tool (from WebLogic) to take a ping (for example, ping 237.0.0.1 assigned to clustered nodes to commnicate each other) it always returns 101 and 103.

So it seems to us network interface has different response order (we don't know). Setup ip_strong_es_model doesn't work either. Anyway we can have correct ping to designed ip? Greatly appreciated your input,

CONFIGURATION (web1):
lan100 192.168.0.101 (apa manual)
lan101 192.168.0.102 (apa manual)
lan0 192.168.0.61 (WebLogic uses)
lan0:1 192.168.0.62

CONFIGURATION (web2):
lan100 192.168.0.103 (apa manual)
lan101 192.168.0.104 (apa manual)
lan0 192.168.0.63 (WebLogic uses)
lan0:1 192.168.0.64

[Brian Hackley]

Brian,

I've noticed your question sitting on the forums without an answer for some time. However, now that I've re-read it, what "jumps out" at me here, is that on each system, you've configured multiple LAN interfaces on the same IP subnet. You can have as multiple VIRTUAL IP's on the SAME subnet, but NOT multiple LAN interfaces/cards/aggregates.

What will happend in any case, is that yes, a packet addressed to an individual LAN interface will go to that LAN interface, but any reply packet will go out the LAST LAN INTERFACE ifconfig'd UP on that IP subnet...
I believe that is the behavior you are noting here.

You can either live with this condition, or seperate the LAN Interfaces (and their associated Virtual IP's) so that they are on unique IP Subnets.

Hope this helps,

-> Brian Hackley