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Albert_Coll's avatar
Albert_Coll
Icon for Cirrus rankCirrus
Feb 07, 2022

Irule to modify the VIP route advertisement setting upon pool down

Hi, I have an Big-IP LTM in which I need to create a procedure to set a VIP "route advertisement" setting to "disabled" whenever a pool goes down. I think that this can be achieved by an iRule.  Do...
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  • Jim_Schwartzme1's avatar
    Jim_Schwartzme1
    Feb 08, 2022

    What you could do is create a gateway monitor and give it an Alias Address of the gwy. Assign that to the pool as a second monitor that is the default pool of the virtual server the vip address is assigned to. That way, when the gwy fails, it marks the pool members down which in turn will retact the advertisment of the route.

Albert_Coll's avatar
Albert_Coll
Icon for Cirrus rankCirrus

Hi Jim, 
Thank you for your post. 

The Big-IP LTM VM is integrated into the network through two Firewalls:
* There is a static default route pointing to a FW in a DMZ, which is the incoming interface of all user's traffic.
* There is another firewall on another interface, through which a BGP session is established to a PE located beyond it.
I redistribute the VIP to BGP to this PE through a redistribute kernel & a route map. 

Now, the network manager requests me to cease advertising the VIP through BGP as soon as the default route fails: I created a pool to properly monitor the default gateway, so that this pool gets down when the gwy stops replying icmps.

What I would need is to define some function (irule, iapp maybe) to disable the "route advertisement" flag when the pool gets down, or triggering some BGP reconfiguration to remove the VIP advertisement.

Regards.

 

Jim_Schwartzme1's avatar
Jim_Schwartzme1
Icon for MVP rankMVP
Feb 07, 2022

Is the pool that monitors the GWY the default pool of the virtual server that is using the VIP that is being advertised? Also, is there a single or multiple pool members?

  • Albert_Coll's avatar
    Albert_Coll
    Icon for Cirrus rankCirrus
    Feb 08, 2022

    The pool monitoring the gateway is not the Virtual Server default pool: This pool is unassociated.

    The default gateway IP address is the only member of this pool.

    • Albert_Coll's avatar
      Albert_Coll
      Icon for Cirrus rankCirrus
      Feb 08, 2022

      But I also posted a reply to James: I guess I shoud use BFD for that purpose.

      Thank you.

      • Jim_Schwartzme1's avatar
        Jim_Schwartzme1
        Icon for MVP rankMVP
        Feb 08, 2022

        What you could do is create a gateway monitor and give it an Alias Address of the gwy. Assign that to the pool as a second monitor that is the default pool of the virtual server the vip address is assigned to. That way, when the gwy fails, it marks the pool members down which in turn will retact the advertisment of the route.