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CSS11500 Keeplaive Service Problem


We are having CSS11500 load balancer used to monitor services on two servers on one particular application port.

We are using following configuration to moniter these services on these two servers.

ip addrss Server_IP_Adress

Port Port_Number_tobe_Monitored

keepalive type tcp

keeplaive port ****

max-failure 3


When we are using this service to moniter the application on the server after some time that application stops listening to that port automatically !!

We stopped monitering this application port and then that application servive starts running and the service keeps on running.

This is really surprising , that how service on server stops due to load balancer keepalives.

What type of keepalive messages are used by CSS11500 to check that the service is running on that port on that server.

If this is not working then in that case we will not be able to moniter the service of that particular application port service and load balaning will not take place.

Any idea why server service is stopping when CSS is used to moniter it.

Or it is aproblem related with Server.

IBM-AIX. is OS on the server.

Thanx in advance



Re: CSS11500 Keeplaive Service Problem

With a keepalive type of TCP, the CSS is simply opening a TCP connection to that address and port, If the connection is sucessful, the service is up. 3 consecutive fails, it is down.

When it went down on the CSS were you able to connect to the application directly?

As to why it hangs after a while? This is probably a resource issue on the server, Maybe when it gets an incoming connection it allocates some resources (eg memory) that remain allocated after the disconnection. It is kind of an issue with the server, and maybe either the application or server people can advise on how it can be handled, or maybe they can tune the application or server to handle it better. It could also be a side effect of DoS protection on the server - "EEK! all these connections and no one is doing anything - I am under attack!"

As to what to do? There are lots of options on the keepalive on the CSS. The least intrusive is the default which is simply a ping. It may be that by slowing the keepalives from the CSS the server can manage better.

You really need to talk to the server people about a suitable keepalive strategy. Ideally you want a URL that the CSS can request of the server that will confirm all is OK, including any backend database access, and that does not hog all the resources on the server.

Unfortunately things like this with a CSS can be a degree of trial and error.