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steph_01_143006's avatar
steph_01_143006
Icon for Nimbostratus rankNimbostratus
Jul 10, 2014

Floating IP not needed if SNAT used

Hello,

 

I implemented 2 BIG-IP active/active with two traffic-groups. The VS are links to SNAT pool, so the floating IP is not needed, the servers in pool communicate with SNAT IP not with floating IP. So I didn't built any floating ip.

 

It seems to work properly, but I would like to know if this design is approved by F5. Or if floating ip is mandatory even if not used.

 

Thank you

 

application delivery
availability
design
LTM
TMSH

4 Replies

  • Vitaliy_Savrans's avatar
    Vitaliy_Savrans
    Icon for Nacreous rankNacreous
    Jul 10, 2014

    Hi,

     

    from guide :"A floating self IP address enables a destination server to successfully send a response when the relevant BIG-IP unit is unavailable. When two units share a floating self IP address, a destination server can send traffic to that address instead of a static self IP address. If the target unit is unavailable, the peer unit can receive and process that traffic. Without this shared floating IP address, the delivery of server traffic to a unit of a redundant system can fail."

     

    In case of one device failure it's usefull feature.

     

  • uni's avatar
    uni
    Icon for Altocumulus rankAltocumulus
    Jul 11, 2014

    I recommend always assigning a self-ip, ever since I got caught by the situation described in sol7336, in addition to that mentioned by Vitaliy above.

     

  • JG's avatar
    JG
    Icon for Cumulonimbus rankCumulonimbus
    Jul 11, 2014

    However, if you have configured MAC masquerading, that helps.

    See:

    [sol11880: BIG-IP objects configured on a different subnet than the self IP address do not send gratuitous ARP requests during failover.](https://support.f5.com/kb/en-us/solutions/public/11000/800/sol11880.html)
  • steph_01_143006's avatar
    steph_01_143006
    Icon for Nimbostratus rankNimbostratus
    Jul 11, 2014

    Hello, thank you for your answers.

     

    The SNAT Automap feature use floating IP, but SNAT pool not because the IPs are defined into the SNAT pool.

     

    So I have only setup MAC masquerading in traffic group for sending gratuitous ARP during the failover. No floating self IP is enabled. I'm continuous to test my design in order to check if all is ok, currently it seems to work properly.

     

    Regards