ACE to load balance proxy servers

[gordonderick]

Hi,

i have a set of 4 proxy servers that are already load balanced. But they are using a incorrectly configured health probe on the ace. I need to know a good configuration for a heath probe that will send a http request over port 80 , wait for response, and read it?  I searched the forum and the cisco pages but could not find a proper answer.        

the current probe is as follows:

probe http HTTPGET

  description Tests that www.gmail.com returns 302 redirect

  interval 10

  request method get url http://www.gmail.com

  expect status 302 302

-Gordon

[Jorge Bejarano]

Gordon,

Maybe this can help:

probe http gordon

  port 80

  interval 15

  passdetect interval 5

  request method head url /gordon/cisco.txt

  expect status 200 200

  open 1

Jorge

[gordonderick]

Hi Jorge,

Thanks for replying. Well i guess this may not work as the config you provided assumes that the server it is being probed is a web server. In our case its a proxy server.

-Gordon.

[ajayku2]

Hi Gordon,

This is what you want to achieve :

I need to know a good configuration for a heath probe that will send a  http request over port 80 , wait for response, and read it?

So ideally you have to choose what content you want to request and what you expect as response.

Any HTTP request will assume that the request is going to the web server or the device can understand HTTP and respond accordingly.

If you ask me I would say that the probes which you are using make sense.

If the probe fails that means the proxy is unable to reach "www.gmail.com" which is almost as good as proxy is not working.

Let me know your thought about it.

regards,

Ajay Kumar

[gordonderick]

Hi Ajay,

Thanks for the response. The problem i am seeing is that when the probe sends out a request to the proxy server it sends it is http://x.x.x.x where x.x.x.x is the ip address of the proxy server. Is this correct?

As you rightly mentioned this is happening because the probe thinks that it is probing a web server. But i want it to think that it is probing a proxy server. Is there a way to make it believe its doing this?

-Gordon.

[ajayku2]

Hi Gordon,

There is no different way to do it. The protocol ( HTTP ) behavior will not change.

If you want to use something else then you may use TCP probe.

regards,

Ajay Kumar

[gordonderick]

Hi Ajay,

i guess that is the way forward. Do you know of any link or document that is available that can give me some examples on TCP probes. I tried looking but could not find much information.

-Gordon.

[ajayku2]

Hi Gordon,

here is the example for TCP probe.

probe tcp TCP
  interval 10
  faildetect 2
  passdetect interval 10
 
you can also refer the guide: 

http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/ace_appliances/vA3_1_0/configuration/slb/guide/probe.html#wp1031228

regards,

Ajay Kumar

[gordonderick]

Hi Ajay,

Thanks. I was looking for probe example to achieve : send a http/tcp request over port 80 , wait for response, and read it. If the data that is read is what is expected then the probe is pass.

I had a look at the guide but it is quite generic and does not give specific information and even does not provide examples of the 'send-data'.

I would appreciate if you have some information on this.

-Gordon.

[ajayku2]

Hi Gordon,

probe http P_HTTP_TEST

  interval 5

  passdetect interval 3

  passdetect count 3

  request method get url /test

  expect status 200 200

  expect regex testdata   <<<---- This is the data you want to parse in order to make the probe successful.

If the regex match fails then the probe will be declare it as failed.

regards,

Ajay Kumar