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zztop123's avatar
zztop123
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Sep 07, 2023
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Remove subnet from NAT pools without any impact

What is the easist way to Remove subnet from NAT pools without any impact

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  • Mohamed_Ahmed_Kansoh's avatar
    Mohamed_Ahmed_Kansoh
    Sep 07, 2023

    Hi zztop123 , 

    Look , 
    you should first see how this pool of NAT IPs used , see if it's used by huge amount of traffic , or by little or isn't used. 

    if this subnet not used , you can remove it , it will not cause any impact. 

    but if this subnet is used much in NATing you should remove it , as you maybe impacted by port exhausion so at this case you shouldn't remove it. 

    So the impact only is with port exhausion not anything else. 

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  • Mohamed_Ahmed_Kansoh's avatar
    Mohamed_Ahmed_Kansoh
    Icon for MVP rankMVP
    Sep 07, 2023

    Hi zztop123 , 

    Look , 
    you should first see how this pool of NAT IPs used , see if it's used by huge amount of traffic , or by little or isn't used. 

    if this subnet not used , you can remove it , it will not cause any impact. 

    but if this subnet is used much in NATing you should remove it , as you maybe impacted by port exhausion so at this case you shouldn't remove it. 

    So the impact only is with port exhausion not anything else. 

    • zztop123's avatar
      zztop123
      Icon for Nimbostratus rankNimbostratus
      Sep 08, 2023

      Thats right , thats what i was concerned with.If we monitor the use and if its use, and we  disable the pool to see the impact ?You think that would be a better idea

      • Mohamed_Ahmed_Kansoh's avatar
        Mohamed_Ahmed_Kansoh
        Icon for MVP rankMVP
        Sep 08, 2023

        Hi zztop123 ,

        Take a packet capture in the server side and see how this pool of NAT ips utilized. 

        If you saw much traffic converted to source ips from the subnet that you want to remove it here you should be careful fron port exhaustion issue. 

        If you don't much traffic use ips from the subnet you need to remove it you can delete it. 

        Look at this article , it explains port exhaustion : https://my.f5.com/manage/s/article/K33355231

         

        So the recommendation is to keep monitor in /var/log/ltm periodically to see if there is port exhaustion or not. 

        If you found this log even one time , you should rollback and return the removed subnet again in the pool.