Forum Discussion
Rabih_74451
Nimbostratus
NimbostratusHealth Checking Internet links behind proxy servers
Hi,
I have a requirement to load balance forward proxy servers with load balancing decisions based on the:
1. Availability of Proxy service itself (squid).
2. Availability of the Internet link that a proxy connects to.
3. Performance of the Internet link that a specific proxy connects to.
We have 3 forward proxy servers, each connected to a separate ISP link.
If an Internet is down the F5 box should be able to detect that and bypass the proxy server related to it.
If the Internet link performance is weak then the 5 box should respond to that by reducing the traffic on the related proxy accordingly (ratio will depend on the link condition).
The F5 salesman is saying that this possible using the F5 base code plus some scripting via iRules. Does anybody know if above is possible and guide me to a written script (if one already exists).
Thank you in advance
Rabih
- JRahm
Admin
There may be a simpler way, but I think you'll get the best bang for your buck by using a pre-configured monitor for your first requirement and then writing an external monitor that would perform steps 2 & 3 are return a pass/fail response. Here's the external monitor wiki page:
http://devcentral.f5.com/wiki/default.aspx/AdvDesignConfig/ExternalMonitor.html Click here 
Rabih_74451Thanks for your reply,
Is it possible to run 3 instances of the same external monitoring each connecting over a separate Internet Link, and based on success/fail test results allow/stop using the proxy server of a specific link.
Is it also possible to test the perfomance and return a grade describing the Internet link, say 1 to 10, and then adjust the priority of the proxy server within the proxy accordingly?
Rabih- JRahmI don't believe you can weight traffic with the external monitor like you can some of the other options (like the wmi monitor) For the granularity of what you're hoping to achieve, you might be better served writing an iControl application that will do all of that checking and configure the availability and the traffic ratios of your proxy pool members dynamically.
- Rabih_74451Thank you for all your help
- Just thought I'd add that Yes, in the configuration you describe, it is possible to monitor the health of each proxy server and its dedicated link by using transparent monitors against 1 or more external targets, and conditioning server status on the success of 1 or more of those monitors.
HTH
/deb
