How to load balance two forward proxy servers that are not transparent?

I don't see any limitation with that, is like load balance to a web server. Just be aware that if you are doing persistence based in the URL, all users going to will use the same server (as an example), and that may overload the server if the URL heavily used.

Hi Wasfi,

I've investigated CARP-Loadbalancing for HTTP-Proxy Servers a while ago. Unfortunately the F5 does not support a flawless CARP balancing for proxy servers. The problems are...

1. Without using OneConnect, just the initial Proxy-Request will getting CARP'ed to the right proxy server node. Subsequent Proxy-Request over the same TCP-Connection will stick to the initial selected proxy server node and may cause redundant cache contents.
2. Using a OneConnect Profile in combination with HTTP-Profiles will allow you to CARP subsequent Proxy-Requests accordingly. But on the other hand OneConnect will by default break any form of Session-Based-Proxy-Authentication (e.g. NTLM, Kerbeors, Negotiate).
3. Using manual OneConnect-Labels will allow you to perfrom CARP for initial and subsequent Proxy Requests with full Session-Based-Proxy-Authentication support, but this approach will create a lot of (idle) Serverside TCP connections and therefor require somewhat huge OneConnect Connection Pools.

You may take a look to my CARP based HTTP-Proxy load balancing iRule (with Tunnel-SSL and full Session-Based-Authentication support) as a starting point. If this iRule is to rocket science / experimental for you, then I would recommend to skip using CARP and simply use Least-Connection balancing for your Proxy Servers.

https://devcentral.f5.com/questions/need-information-on-oneconnectselect-48701

Cheers, Kai