ACE redirection question

Answered Question
Jun 5th, 2009
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Hi All,


Supose I got 1 VIP serving a serverfarm with 2 servers. Is it possible to configure the ACE in a way that if any of the servers goes down, all the requests to this serverfarm are redirected to another serverfarm?


I've tried to use backup rservers but in this case all the servers in the serverfarm had to be down for the backup server to take up.


Any thoughts?

Claudio.

Correct Answer by ciscocsoc about 7 years 9 months ago

Hi Claudio,


You don't need to configure two probes. If you use the "partial serverfarm failover" technique then you can achieve waht you want. With the partial technique as serverfarm is marked as down if less than a specified percentage of the servers are available.


serverfarm FARM1

partial-threshold 60 back-inservice 100


policy-map type loadbalance ...

class class-default

serverfarm FARM1 backup FARM2


HTH


Cathy

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huangedmc Sat, 06/06/2009 - 20:19
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This is an unusual requirement, since the idea of running multiple servers behind a VIP is to provide redundancy, so that if one server fails, it'll still be ok, since the other server can still serve clients.


You're correct that the backup farm would only kick in only if the primary farm goes down.


One way to make that happen is to create a probe so that the two servers actively monitor each other.

If one fails the probe on the other one would fail too.


Once again this is an odd request - do you mind explain the reason behind it?

cfrosa Sun, 06/07/2009 - 17:06
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Hi huandedmc, thank you for your suggestion!


I do agree that this is not an ordinary request. My customer is testing a vendor aplication and because of old hardware he needs two servers in order to be able the handle the requirement. If one server goes down the other wont be able to handle the requests. So, in the event of one server failure all te requests should be redirected to another, more powerfull server. This third server is being used by other applications and the business has offered it to be used just in case othe the primary serverfarm be down.


Thanks

Correct Answer
ciscocsoc Mon, 06/08/2009 - 00:42
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Hi Claudio,


You don't need to configure two probes. If you use the "partial serverfarm failover" technique then you can achieve waht you want. With the partial technique as serverfarm is marked as down if less than a specified percentage of the servers are available.


serverfarm FARM1

partial-threshold 60 back-inservice 100


policy-map type loadbalance ...

class class-default

serverfarm FARM1 backup FARM2


HTH


Cathy

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