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I have active/passive servers cluster talking with another cluster located behind a Router, for some bug in the operating system in the first cluster it did not send GARP message after switch-over and the communication with the second cluster will be broken till either the ARP cache timed out on the router or someone clear the ARP cache table on the router manually. to resolve this I have two options, Either reduce the cache timeout on the router or implement script and add it to the switch-over procedure to be called automatically during switch-over, but the first option look easier to implement and more safe. I have concern that reducing the cache timeout on the router would cause high broadcast on the network,is it safe to reduce the Cache time out?

Mr.lock
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    Re: "I have concern that reducing the cache timeout on the router would cause high broadcast on the network,is it safe to reduce the Cache time out?" Short answer: it depends on the number of attached systems, but for any reasonable number (i.e. attached systems not measured in thousands), then the answer is "yes, you can reduce your ARP timeout". Also see **[this answer](https://networkengineering.stackexchange.com/a/2193/775)** which reduced the ARP timer for different reasons – Mike Pennington Apr 20 '17 at 18:10
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide your own answer and accept it. – Ron Maupin Aug 07 '17 at 16:37

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I have personally done that ARP timeout set to 60 sec for a single VLAN caused 0.05% ARP usage on cisco 29XX series. It is running like that for over a month. No problems at all. Still I'd not recommend using the network for solving clustering problems.

Viktor Borisov
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