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New Member

Failover for server farm

If you have a basic configuration on the ACE which consists of

VIP --> serverfarm -----> server1

                           -----> server 2

if one of the servers is removed or fails will the ACE detect this without probes being configured? and if so how does it detect the failure?

thanks

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Failover for server farm

When you doesn't configure probe, ACE only detects server down with arp table.

It mean rserver goes down when arp timer is expired and rserver state will become ARP_FAILED.

Default arp timeout of rserver is 300 seconds as below.

ACE20/Admin# sh arp timeout

Context:Admin

Refresh Time:

   Learned Address      : 14400 seconds

   Configured Address   : 300 seconds

Retry Rate              : 10 seconds

Max retries per host    : 3

Periodic Sync Interval  : 5

You can change this value with 'arp interval' command on configuration mode.

However, this configuration change effects all configured address.

So, I recommend you configure probe.

Regards,

Yuji

4 REPLIES
Silver

Re: Failover for server farm

Hi,

There is no automatic failure detection. You need to have some form of health probe.

HTH

Cathy

New Member

Re: Failover for server farm

So if a server is rebooted or disconnected, it will still send data to it?

Cisco Employee

Re: Failover for server farm

When you doesn't configure probe, ACE only detects server down with arp table.

It mean rserver goes down when arp timer is expired and rserver state will become ARP_FAILED.

Default arp timeout of rserver is 300 seconds as below.

ACE20/Admin# sh arp timeout

Context:Admin

Refresh Time:

   Learned Address      : 14400 seconds

   Configured Address   : 300 seconds

Retry Rate              : 10 seconds

Max retries per host    : 3

Periodic Sync Interval  : 5

You can change this value with 'arp interval' command on configuration mode.

However, this configuration change effects all configured address.

So, I recommend you configure probe.

Regards,

Yuji

Cisco Employee

Re: Failover for server farm

ACE will still send data until it detects server down.

After ACE detects rserver down, it doesn't send new connection to this server.

Regarding existing connection, it depends on the 'failaction' configuration on serverfarm mode.

Regards,

Yuji

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