For more information regarding the security incident at F5, the actions we are taking to address it, and our ongoing efforts to protect our customers, click here.

Forum Discussion

Miguel_61449's avatar
Miguel_61449
Icon for Nimbostratus rankNimbostratus
Sep 28, 2011

Internal big ip ltm flow consultation

Hello all,

 

 

I would like to inquire about the operation of iRules and the http_class in a big-ip ltm system. I have a pretty good idea of how these resources work and can be allocated to virtual servers, however, I have not very clear the order of application of these two resources.

 

 

For example, if there is any inconsistency between the definition of iRules and http_class (say, the iRule sends the traffic to pool_A and the http_class send traffic to pool_B and to both resources are associated to the same virtual server) which would be ejecuted? The iRule or the http_class.

 

 

Is there any documentation describing in detail the functioning of the internal data flow in a bib-ip f5 and the correlation between iRules and http_class?

 

 

Thanks you in advance.

 

 

Miguel.
config
design

2 Replies

  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Sep 28, 2011
    Hi Miguel,

     

     

    An iRule can have multiple events which execute before and after the HTTP class(es) are evaluated. Here's a quick list:

     

     

    CLIENT_ACCEPTED - TCP connection from client to VIP established

     

    HTTP_REQUEST - client's HTTP request headers parsed

     

    HTTP_CLASS_SELECTED (if a matching class is found for a request) or HTTP_CLASS_FAILED (if no matching class is found for a request). If a pool is added to the HTTP class and it matches the request, the pool selection will override the VS default pool and any pool selected in the HTTP_REQUEST event.

     

    LB_SELECTED - pool member selected

     

    SERVER_CONNECTED - TCP connection from LTM to server established

     

    HTTP_REQUEST_SEND - just before the HTTP request is sent to the server

     

    HTTP_REQUEST_RELEASE - last chance to inspect/modify HTTP headers only before request is sent to pool/node (added in v11.0)

     

    HTTP_RESPONSE - server's HTTP response headers parsed

     

    HTTP_REQUEST_RELEASE - last chance to inspect/modify HTTP headers only before request is sent to client (added in v11.0)

     

    SERVER_CLOSED - LTM to server connection closed

     

    CLIENT_CLOSED - client to VIP connection closed

     

     

    Aaron