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Dario_19875's avatar
Dario_19875
Icon for Nimbostratus rankNimbostratus
May 11, 2010

LC no longer supporting HTTP fallback

Hi all,

 

 

I have a deployment of 2 Link Controllers v10.1.0 at a customer, which will replace the customer's current LCs v4.5.14.

 

 

In his current LCs, we had the possibility to define a 'fallback host' in case no pool members were active. A HTTP redirect was send that points to a page saying the website is down for maintenance.

 

 

In the new version, this feature is apparently no longer available.

 

 

After searching ask.f5, we found an iRule using HTTP_REQUEST and HTTP::redirect, but get an error stating 'ltm_rule_L7 feature not licensed'.

 

 

Do you have any idea how we can accomplish this? Or is buying an LTM license only for this the only valid solution?

 

 

Thanks in advance.

 

 

Br,

 

Dario

 

config
design

10 Replies

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  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    May 11, 2010
    Hi Dario,

     

     

    I don't think there is a way in a LC-only license for v9/10 to do this.

     

     

    Aaron
  • Dario_19875's avatar
    Dario_19875
    Icon for Nimbostratus rankNimbostratus
    May 20, 2010
    Hi,

     

     

    I've found an iRule that could work, but at the moment it isn't working 100%:

     

     

    when CLIENT_ACCEPTED {

     

    if { [active_members POOL_NAME] < 1 } {

     

    TCP::respond "HTTP/1.1 302 Redirect\r\nLocation: http://URL/\r\nConnection: Close\r\n\r\n"

     

    }

     

    }

     

     

    The weird thing is, when testing using Chrome as internet browser, my request is redirected and everything is working fine.

     

    When doing the same thing with IE or Firefox, an error occurs.

     

    IE just gives me the page that a connection error has occured, Firefox gives me a Connection Interrupted: The document contains no data.

     

     

    When changing the 302 to 301, again Chrome works fine, IE also works fine but still Firefox gives me the same error.

     

     

    When sniffing, I see the same HTTP redirect being send, so I assume it is browser related.

     

     

    Anyone had this problem before or can explain where it goes wrong?

     

    Anyone can point me in the correct direction?

     

    Can I adopt my iRule to get this to work?

     

     

    Thanks in advance!

     

     

    Dario
  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    May 20, 2010
    At a quick guess, I'd surmise that the browsers don't like an HTTP response coming back before they've made their request..

     

     

    (CLIENT_ACCEPTED fires as soon as the connection is made, and (Depending on load) will probably fire well before the client has a chance to send the request)...

     

     

    H

     

  • Dario_19875's avatar
    Dario_19875
    Icon for Nimbostratus rankNimbostratus
    May 20, 2010
    Hi,

     

     

    I've checked the traces, and see that the HTTP GET is first done. In response to that, the 302 redirect is send.

     

     

    Any idea by which is can replace CLIENT_ACCEPTED?

     

     

    Thanks,

     

    Dario
  • Cspillane_18296's avatar
    Cspillane_18296
    Icon for Nimbostratus rankNimbostratus
    May 20, 2010
    Hi Dario,

     

     

    does using "when HTTP_REQUEST" as the iRule Event give you any better result? I'm afraid I don't have time to test this but I fear it might still not work, it may depend on the Virtual Server type (see SOL8082). However if you have the time a quick test will show one way or the other.

     

     

    Good luck!
  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    May 20, 2010
    I believe that was covered in the first post... Those events don't appear to be available in the version he's running with an LC only license...

     

     

    H
  • Dario_19875's avatar
    Dario_19875
    Icon for Nimbostratus rankNimbostratus
    May 20, 2010
    Hi,

     

     

    found a solution which works:

     

     

    CLIENT_ACCEPTED {

     

    if { [active_members POOL_NAME] < 1 } {

     

    TCP::respond "HTTP/1.1 302 Found\r\nServer: webserver\r\nLocation: http://URL\r\nAccept-Ranges: none\r\nConnection: close\r\nContent-Length: 0\r\n\r\n\r\n"

     

    TCP::close

     

    }

     

    }

     

    }

     

     

    Thanks all for the replies.

     

     

    Dario

     

  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    May 20, 2010
    Posted By Cspillane on 05/20/2010 07:35 AM

     

    Silly me, you're quite right Hamish! I'll go hide somewhere in shame...

     

     

    I think I've made worse...
  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    May 20, 2010
    Posted By Dario on 05/20/2010 07:37 AM

     

    Hi,

     

     

    found a solution which works:

     

     

    CLIENT_ACCEPTED {

     

    if { [active_members POOL_NAME] < 1 } {

     

    TCP::respond "HTTP/1.1 302 Found\r\nServer: webserver\r\nLocation: http://URL\r\nAccept-Ranges: none\r\nConnection: close\r\nContent-Length: 0\r\n\r\n\r\n"

     

    TCP::close

     

    }

     

    }

     

    }

     

     

    Thanks all for the replies.

     

     

    Dario

     

     

     

    Ahh.... It's possible that firefox is waiting for content... Because your original response had a header, and then nothing for response body... Now you're sending a CL header of 0, and an extra EOL... I wonder if it's the extra EOL or the CL header that firefox really wanted...