IP address on global keepalive

[csiracusa]

CSS configuration with keepalive named set an IP address to the global keepalive.

Into the Cisco document we can read

"Configuring a Global Keepalive IP Address

The CSS sends global keepalives to a service that monitors the state of services assigned to it. Use the ip address command to specify the IP address where the keepalive messages are sent."

This means that we need a dedicated external service to monitor the real services?!

Best Regards

follow the URL :

http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/css11500series/v7.40/configuration/content_lb/guide

[Gilles Dufour]

not sure what you mean by external service.

All this document says is said your service runs on a machine which has an ip address, and you need to configure it in the keepalive section.

Gilles.

[csiracusa]

Hi Gilles,

I mean, a dedicated service (not defined into the css) that monitor all the services that I have to monitor through the global keepalive.

I said this because I have done a test, I have used for the global keepalive the IP address of a service (one of three) that have to use this global keepalive.

When I put this service in down (disabled the port of the attached switch) all the global keepalive goes down and then the relative rule con css although the other two services was alive.

Please, can you help me understand what else the sentence mean?!

Thanks

Regards

[Gilles Dufour]

each service can have its own keepalive than you configure under the service.

Sometimes, 2 or more services would actually monitor the exact same service (tcp port).

Therefore, instead of having 2 or more services polling the same port, you create a global keepalive and use it for all the services sharing the same parameter.

Hope this makes sense like this.

Gilles.

[csiracusa]

But the question is the same, what's the IP address of the global keepalive?!

Into the test that I have done it seams that this IP address is IP of an external server (not inside the css) that have to monitor all the services where I'm applying the global keepalive.

But I cannot undestend the use or the utility of it.

Regards

Cinzia

[Gilles Dufour]

Let's say you have a server that runs HTTP and FTP.

You create the following services

service A-http

..

service A-ftp

..

They will have their own separate keepalive.

NO global keepalive.

But then you create a generic service for server A.

ie:

service A-generic

ip x.x.x.x

active

And you want this service to be alive when the http port is alive.

You can simply add 'keepalive type http'.

But you already have another service sending http keepalive to that server.

So, if you add 'keepalive type http' to this new service, the CSS will send 2 probes for the same service.

So, to avoid sending 2 probes, you create a GLOBAL keepalive.

This global keepalive is configured with the ip address of the server and keepalive type http.

You then assign this global keepalive to the 2 services that need it.

This is as simple as that.

You only need global keepalive if 2 or more services use the same keepalive.

The ip address is the one used by the 2 services.

Gilles.

[csiracusa]

So, a global keepalive can be applied to more than one service ONLY if this services have the same IP address, and than, the global keepalive will have the same IP address.

Is that correct?!

Thanks

[Gilles Dufour]

Basically, yes.

But the CSS allows you to use it with different services having different ip addresses.

It's just that only the ip address specified in the global keepalive will be checked.

Gilles.

[csiracusa]

Hi Gilles,

I mean, a dedicated service (not defined into the css) that monitor all the services that I have to monitor through the global keepalive.

I said this because I have done a test, I have used for the global keepalive the IP address of a service (one of three) that have to use this global keepalive.

When I put this service in down (disabled the port of the attached switch) all the global keepalive goes down and then the relative rule con css although the other two services was alive.

Please, can you help me understand what else the sentence mean?!

Thanks

Regards