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Stewart_76633's avatar
Stewart_76633
Icon for Nimbostratus rankNimbostratus
Oct 31, 2012

LTM on different subnets (layer 3 routing)

Hi Guys,

 

I'm running a f5 POC at the moment with 2 1600 appliances. I have two data centers which are seperated via routing (ie not layer 2 spanned Vlans). I was under the impression I could have these devices in a cluster, on different subnets and have routing take care of the HA and production (ie server facing) vlans. I've run into an issue syncing config though,.

 

DC1 1600 - HA 1.1.1.1

 

DC2 1600 - HA 2.2.2.2

 

On DC1 I have a static route to 2.2.2.2, and on DC2 I have a static route to 1.1.1.1. This is so the traffic exits through the HA interface not the production interface. This works fine however when the config sync happens I get an error along the lines of 1.1.1.1 is directly connected to DC1 so won't sync, and vica versa for the other device.

 

As far as I can tell the only way this route sync would work is if they shared the same subnet (and default gateway) so the route would not be neccassary for them to chat to each other.

 

 

Is there anyway around this? While it may be technically possible for me to span a VLAN across the two DC's it would break a 'model' we currently have. I'd rather not.

 

Thanks

 

 

config
design

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  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Oct 31, 2012
    why do you want to make a cluster across data centers with different vlan?

     

     

    if you want active/standby, is ip anycast (route health injection) not usable?
  • Stewart_76633's avatar
    Stewart_76633
    Icon for Nimbostratus rankNimbostratus
    Oct 31, 2012
    We want active/active as some VIP's will be available on the primary DC, and some on the secondary. We will manipulate this by RHI and BGP. ie if VirtualServer A is at DC1, the DC1 device advertises the route into our routing core, and vica versa if we want VIP's at DC2.