Forum Discussion
jrok_47156
Apr 15, 2013Nimbostratus
When you start talking about Layer2 and the TCP stack, you are loitering on the outskirts of my knowledge, that's why I didn't respond appropriately to your earlier comment, sorry. Routers, firewalls, hubs, switches, etc. I am fine with and can have a loose conversation about them - but I'm not down with the stack you know, it's over my head.
Here's my situation. I have about a dozen servers sitting behind the F5 running six different applications with a couple servers in each pool. I needed a way to be notified immediately when an entire pool went down so that I could react to it. So I built another IIS/App "warning" server that would accept http requests destined for any of the app pools, decipher their original destination domain and then send emails and sms message out to our team. So when an entire pool goes down I use the pool command in an iRule to send it instead to my down-time-service pool and "warning" server. This all works swimmingly. What I decided to add was a new part of the rule that if just one of my two nodes for any particular pool goes down I would send the real request on through to the app pool but also send a clone of the request to my new node-down-service pool and "alert" server that would again decipher the original destination and alert the team that one of the nodes has failed so we can address it.
There is a better description of my situation with the actual iRule code here from last week:
https://devcentral.f5.com/community/group/aft/2166542/asg/50