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I have a ISA server 2006 and all my HTTP request are forward to another proxy. I have configure ISA for that, when the proxy is unreachable, ISA does the request directly. My problem is that when the proxy is online again, the request are sent directly, ISA don't use the proxy again even after some time. The only solution I found is restart ISA.

Do you have a solution for that ISA forward the request to the proxy when it's back online ?

Thanks for advance.

Sébastien
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  • ISA generally detects when the upstream proxy becomes available (I want to say within a minute, but I can't remember if 30 seconds or 3 minutes were significant numbers). Are you using the latest update rollup? Also, there are two settings that look alike - one is for web chaining (what you're describing), one is for client browsers. – TristanK Apr 04 '12 at 05:08
  • Ok I think that I forgot to say that the another proxy is not an ISA server. So maybe that the availability detection works only between two ISA server ? – Sébastien Apr 05 '12 at 08:32
  • Nope, it's based on TCP. The "polling URL" is an ISA-specific thing, but the failover detection works with any old proxy. Does it eventually recover if you leave it alone? (Is a Connectivity Restored event logged)? It might be triggered based on client requests, so if you've a low-N number of clients or exclusively use long-running requests, it might vary. I have seen it work before at many clients' networks. Maybe look at your build version, grab the latest rollup if you're not already on it. But I'd be surprised if it was that alone. – TristanK Apr 05 '12 at 10:01

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Ok, I have found what was the problem and how to fix it. The web chaining feature of ISA was made to chain two ISA togather. I was trying to chain ISA with another proxy.

When ISA loose connection with the proxy, it will regulary check if it's up. This request is : "GET /array.dll" (with some get parameters but it's not really important). So the solution is very simple, the proxy MUST answer a HTTP response. Even it's a 404 or any error code (for what I have see). My proxy just ignored the request so ISA didn't receive any response.

Sébastien
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