ACE real server rate liiting

Unanswered Question
May 24th, 2009


If the ACE is configured to rate limit the traffic to a given real server to a certain bandwidth, what happens to the traffic that exceeds the specified limit ? Does the ACE drop this traffic in all cases as the documentation says ? Or can we configure the ACE to bypass this traffic either without any load balancing or to a backup server ?

Thanks and regards

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Gilles Dufour Mon, 05/25/2009 - 01:34

on a server has reached its quota we put it "out-of-rotation" so it does not appear available for the next request.

ACE will select another valid rserver.

If none available we select the backup or drop the connection.


thedinuka Mon, 05/25/2009 - 02:19

Hi Gillies, Thanks for the response. Is there a possibility to bypass or send to backup only the amount of traffic that exceeds the set rate limit. What We need is the ACE to send only 155Mbps of total web traffic to a caching server, and to bridge or route the traffic exceeding that limit. This does sounds like a bit of a impossible task to handle, but thought I should verify it with you guys first



Gilles Dufour Mon, 05/25/2009 - 03:00

Sounds possible.

Configure a serverfarm with your cache engine. Set the rate-limit command under the rserver.

Configure a serverfarm with rserver representing default gateways.

Set the serverfarm as transparent.

Configure this gateway/transparent serverfarm as backup of the first one.

This should do what you need.


thedinuka Mon, 05/25/2009 - 03:39

That sounds good, When there is excess traffic, all the new connections would be sent to the serverfarm representing the DG. Now when the traffic level of the cache due to the existing connections decrease below acceptable levels, the ACE will again bring it in to rotation.

Cool, One question though. What happens if there are two caching servers, and we want to implement the same to both the servers. I'm thinking the net effect would be similar. But would there be any caveats ?

Gilles Dufour Mon, 05/25/2009 - 04:13

It would work with as many caches as needed.

Only caveat is that you do not optimize disk space with such a solution.

Your caches might be in and out of rotation.

So even if a file exist in a specific cache, if this cache is already at 155mbps, the request will be either sent to the other cache or sent out.



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