topic Re: Two network interfaces load balancing in Operating System - HP-UX

Two network interfaces load balancing

Zelenskii Andrei — Fri, 12 Jan 2001 13:35:33 GMT

Hi Experts!

Does anybody know, - is there possibilities
to make load balancing over two network interfaces on same server? (both in the same subnet)

Mean by software method.

Thank you in advance.

Re: Two network interfaces load balancing

Berlene Herren — Fri, 12 Jan 2001 15:01:35 GMT

Yes. Included with AutoPort Aggregation software is something called Lan Monitor. This has a "hot standby" feature whereas if one card fails, the other comes up.

see
http://docs.hp.com/hpux/onlinedocs/netcom/hp_apa_using11i.pdf

and

http://docs.hp.com/hpux/onlinedocs/J4240-90005/J4240-90005.html

Berlene

Re: Two network interfaces load balancing

rick jones — Fri, 12 Jan 2001 19:22:07 GMT

APA is the proper way to go here, but if you are really strapped and cannot buy the software, you might get part of the way there through some cruder and less effective means. This presumes that your system is a server, responding to queries from others, and not initiating connections on its own.

First, you would do something to balance the use of the two IP addresses by your clients. One way would be to implement a DNS round-robbing scheme. each time they ask for the IP address(es) of your server DNS RR would shuffle the order of the IPs in the reply.

Another even cruder way would be to have two names, one for each IP address, and tell 1/2 your clients to use one name, the other half the other.

Next, on the server, you use ndd to set the parameter ip_strong_es_model to a value of one. This tells the transport (among other things) to use the source IP address in addition to the destination IP address when selecting outbound routes. In a nutshell, it means that if the request comes-in on interface 1, the replies will also go out interface 1.

However, like I said above, APA is really the better way to go. It will load balance, allow you to only consume one IP address, and will do automagic failover if one link goes belly-up.

Re: Two network interfaces load balancing

Zelenskii Andrei — Wed, 14 Feb 2001 14:12:52 GMT

Exact answer and great ideas.

Thanks a lot.