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Bob_Porambo's avatar
Bob_Porambo
Icon for Nimbostratus rankNimbostratus
May 29, 2019

Changing netmask for self-ip and floating-ip V12

I've read several articles within regarding the ability to change the netmask on a vlan. Some recommend editing the base.conf file and reloading while others indicate we should shy away from that method.

 

I wanted to use tmsh to modify the self IP and the floating IP but it we keep getting the warning about conflicts. We can't seem to be able to modify both at the same time. I understand.

 

I'm a little shy about modifying the base.conf file and reloading. I'm working on a 3-LTM cluster with hundreds of virtual servers so there is concern about any interruption in service if the load fails. The specific vlan in question only has a small number of virtual servers so I'm not concerned about their availability. Am I being overly cautious with this method?

 

If I decide to do this via GUI and/or TMSH by tearing down virtual servers, removing the floating IP, modifying the self-ip, and rebuilding, is there a reason that I must work on the "active" LTM first for that vlan (as it was mentioned in a prior article) or does it matter on which LTM I should start?

 

Thanks,

Bob

application delivery
LTM

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  • rafaelbn's avatar
    rafaelbn
    Icon for Cirrostratus rankCirrostratus
    May 29, 2019

    Hello Bob!

     

    I think you will have to do on the active first because if you try to mess with the standby it will complain about a mismatch regarding the float IP and the self ips.

     

    My suggestion to you is schedule a window, remove the float, sync, remove all selfs and then re-add everything with the new netmask.

     

    I would also advise against editing the config file manually.

     

    Best of luck.

     

    Cheers, Rafael.

  • Oscar_Pucheta's avatar
    Oscar_Pucheta
    Icon for Cirrus rankCirrus
    May 29, 2019

    I would do it modifying the bigip config files. creating a backup first for obvious reasons. Remember the non floating self ip are not sync'd between the boxes, only the floating self ip are. I don't see why you shouldn't do it on the standby units first, it is the reasonable thing to do. I would do this, starting with the standby:

    -Create UCS backup

    -Create a copy of bigip config files (bigip_base.conf and bigip.conf) just in case

    -Modify mask for floating and not floating at the same time

    -run:

    tmsh load sys config base verify

    tmsh load sys config verify

    -if all is good, then run:

    tmsh load sys config base

    tmsh load sys config

    -Proceed with the other units.

     

    Best Regards,

    Oscar Pucheta

    https://www.australtech.net

    https://www.linkedin.com/in/npucheta/