APA Config - load balancing

[K Kantola]

We have a 2 node cluster (HPUX) with APA in use on each node. Each box has two ports in aggregate. I see it load balances inbound traffic but not outbound traffic, all that goes out over one interface. Is this normal or is there a setting to load balance outbound traffic?

[Eric SAUBIGNAC]

Bonjour,

First I would like to clarify a point : HP-UX APA boxes are supposed to balance their own output packets and ethernet switches are supposed to balance their own output packets. In other words, HP-UX does no balancing with input packets.

So "I see it load balances inbound traffic" is improper. If you can see load balancing on input packets, it is the fact of the switch, not of HP-UX.

And I am a bit surprised that you can see input load balancing. Generally, when configured in manual mode, switches don't realize any balancing. How have you configured your APA : manual, Cisco FEC or LACP ?

Now, if you see no output balancing, maybe the load-balancing algorithm you chose is not adapted. In a summary you should choose "IP-based" when the server speak with remote sites (or IMHO with others node on the same lan), "MAC-based" when the server is supposed to speak with others node in the same lan, and "Port-based" when the server is supposed to speak with a dedicated server.

For exemple, suppose that in your cluster each of the 2 nodes has 2 network : one we will call the private network where the 2 nodes speak together, exchange files, etc ... and one call the public network where local client computers connect to the application. In such a situation you should configure "Port-based" on the private network, and "MAC-based" (IMHO "IP-Based" could also works well) for the public network.

You will find an attached graph on a site with APA configured in manual mode/Port-based. It is a situation where 2 servers are speaking togeteher, and only together, with 4 NIC each in an APA aggregate. You will see good balance on output packets and no balance on input packets. Output packets are showed in percentage.

Hope this will help

Regards

Eric

[K Kantola]

I understand that the switch really handles inbound load balance. When I say I see outbound not load balancing, I am looking in GlancePlus. When I pull up network and drill down to interfaces, you can see the inbound split between the two aggregated ports but all outbound goes out over one port only. This cluster is running Openview so the 'hot' node is talking to the rest of the LAN rather than talking to just the other box in the cluster. Ours is set up MAC based since it talks to the LAN. When you say the policy configured might not be adapted, would a restart take care of that?

Thanks

[K Kantola]

no answer

[Dave Olker]

Hi,

Have you tried configuring different load balancing policies to see if the behavior changes? I've had cases where MAC-based load balancing didn't work because the MAC addresses of the connecting systems were so similar that they hashed to the same outbound port on the APA trunk, and thus defeated the load balancing algorithm.

Does switching to PORT-based or CPU-based load balancing change the behavior?

Regards,

Dave