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New Member

AS400 High Availability - Role Swapping

How long will it take a user's PC to recognize and switch from a production (primary) AS/400 to a backup (secondary) AS/400 if the backup AS/400 automatically assumes the exact same IP address of the primary AS/400 if it detects that the primary AS/400 has gone down.

We have two AS400 systems at two different sites. The systems are being setup to role-swap if the production (primary) AS/400 goes down. We have a 6509 switch/router at each site. The 6509's at each site are connected together via a trunked Gigabit fiber connection. The AS/400 connection to the 6509's at each site will be on the same subnet. If the primary AS/400 system goes down, the backup AS/400 system will automatically change it's own IP addresses so that they are exactly the same as the primary -thus assuming the role of the primary system.

How will the switches and connected users respond when a system automatically disappears from one switch port and appears at another. If they just continue to communicate with the newly located connection, how long does it take for the network to re-direct?

New Member

Re: AS400 High Availability - Role Swapping


A quick answer would be that it depends on how long your mac-address-aging time is. This is as far as your layer-2 config. THis coupled with the delay in the as400 taking/releasing the primary role.

I would make sure that you don't have port secutiry turned on for either of these servers as this will disable the failover capability due to the switch securing the mac address per vlan. If you need more info, let me know. I would say test it.

I do have a set of role-swapping 400s. However, our role-swap is done manually and takes quite a bit of time.


New Member

Re: AS400 High Availability - Role Swapping

Thanks, Bo. We are going to try it soon.

New Member

Re: AS400 High Availability - Role Swapping

We use Local Area Mobility to handle faolover between our AS400's.

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