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anesler_160409's avatar
anesler_160409
Icon for Nimbostratus rankNimbostratus
Feb 06, 2015

Two Networks in the same VLAN? Is it possible?

At a technical perspective, it seems like it would be simple to do. Create a new self-IP from a new subnet, but just assign it in the same VLAN and have your servers set their default GW to that self-IP. The only issue I'm running into now, is getting the servers from the old network, talk to the new.

 

I have static routes built out on the OEs, but wasn't sure if there were any additional configurations that were needed on the F5.

 

Thanks

 

application delivery
LTM
vlan

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  • StephanManthey's avatar
    StephanManthey
    Icon for MVP rankMVP
    Feb 06, 2015

    Hi anesler,

     

    if your BIG-IP is used as a router to handle traffic for servers in different IP ranges it will be necessary to configure forwarding virtual servers.

     

    These will be network virtual servers of type "Forwarding IP", port "any, protocol "any" with fastL4 profile assigned.

     

    The destination network will be specified as the network and mask and that´s it.

     

    Two of these virtual servers will be required to handle bi-directional traffic.

     

    SNAT will not be necessary in my opinion, as the responses to the "remote" network will be send to the default gateway (represented by the floating self IP on VLAN).

     

    This setup can be improved by defining service specific virtual servers i.e. to handle long lasting sessions with specific profiles assigned or i.e. DNS traffic with a virtual server on UDP/53 with a udp_gtm_dns profile assigned.

     

    Thanks, Stephan

     

  • Mahmoud_Eldeeb_'s avatar
    Mahmoud_Eldeeb_
    Icon for Cirrostratus rankCirrostratus
    Feb 07, 2015

    yes, you can use two networks or two different subnets sharing same vlan id, however it is not recommended

     

    • Mahmoud_Eldeeb_'s avatar
      Mahmoud_Eldeeb_
      Icon for Cirrostratus rankCirrostratus
      Feb 07, 2015
      Don't forget to mark the answer as the solution if you would, please.
    • boneyard's avatar
      boneyard
      Icon for MVP rankMVP
      Feb 10, 2015
      cant speak for Mahmoud, but i do agree. you are adding complexity and with great chance on errors and difficult troubleshooting. if you dont have a very good need for this, dont do it.