Two-tier ACE config question

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Sep 27th, 2009
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I am an ACE newbie - I have a two-tier ACE setup and I am basically trying to get the front-end ACE to divert to a sorry page if the back end servers hanging of the Back-end ACE do not reply to their probes.

I have the following setup...



DMZ ACE (doing SSL termination)


Reverse Proxy Server farm


Corporate LAN ACE


Application Server farm

DMZ ACE is probing Rev Proxy farm on TCP 2000 - and using sticky cookie insertion.

Corporate LAN ACE is probing App Server farm on TCP 2000 - and using sticky cookie insertion.

If the Application server farm becomes unavailable, I would like the DMZ ACE to detect this and then redirect the clients to a 'service unavailable' page hosted on the Reverse Proxy Servers.

My thought so far is the following...


rserver Rev_proxy1


rserver Rev_proxy2


probe icmp probe_icmp

ip address <App_Server_VIP>

serverfarm Rev_proxy_farm

probe probe_icmp

prove probe_tcp_2000

rserver Rev_proxy1, Rev_proxy2

So the above Rev_proxy_farm availability is tied to the appearance of the App Server vip due to the directed icmp probe to the Corporate LAN ACE VIP - the VIP will disappear if the App Server farm does not respond to it's TCP probe.

I am then not sure how to redirect the HTTP request to the Reverse Proxy Server seeing as though these have already been flagged unavailable.

Should I then follow 'Configuring a Sorry Server Farm' as per to divert the connections from the Reverse_proxy:2000 to Reverse_proxy:3000 (which serves Service unavailable page)?

Any advice on whether this is the best way to go would be much appreciated.



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Gilles Dufour Mon, 09/28/2009 - 00:21
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  • Cisco Employee,

you need to create a redirect host and serverfarm and use this serverfarm as a backup serverfarm for your main serverfarm.

I'm not sure that the icmp ping will work.

Because the ping will be sent to dest ip address of the vip, but the dest mac-address ill the rev-proxy where your configured the probe.

Give it a try.



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