ACE failed probe and established connections

[Jan Rolny]

Hello,

I have four ACE 4710. Each pair of ACE is in one geographical location. Probes are configured so that it is checking regular regex (HTTP GET).

When there is need rserver update we change text in our testpage.html (for ie. from "OK" to "SUSPEND" ) so that probe detect fail.

In fact rservers are still operational, but should not accept new connections. This works fine.

BUT I observed that established connection/sessions did not end up after probe fails. ACE probably wait for openned/established connections to end up and it is what I am askign for.

What happens if probe fails but in fact rserver is operational? I thought that if probe fails it also end up/cut all established connections to rserver. But seems it is not true. Does anybody has this experience?

Thanks for your opinion.

Jan

[Francesco Casotto · Accepted solution]

Hello Jan,

if I understood correctly what you're looking for is domented in the area for the failaction command which actually makes the ACE behavior on this aspect configurable:

http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/ace_appliances/vA4_2_0/configuration/slb/guide/rsfarms.html#wp1117375

indeed the default behavior of the ACE is to take a  failed real server out of load-balancing rotation for new connections  and to allow existing connections to complete.

Hope it helps,

Francesco

[Jan Rolny]

Hi Franceso,

thank you for answer. Information if connections will remain or not is not available in documentaation for ACE. I did not find it. So than it was surprise for me that sw engineer told me that they changed content in testpage.html to fail over and we saw connections in their application log next 10 minutes after chagne. So they could not start update and have to wait for connecton to end up correctly.

But on the other hand it seems it is correct behavior because in this case client will not see any outage of service.

Regards,

Jan