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Edward_Gastón_S's avatar
Edward_Gastón_S
Icon for Nimbostratus rankNimbostratus
Jun 18, 2018

SNAT POOL

Hello Community,

 

One question,

 

I have configuration F5, with traffic SMTP Outgoing with virtual server type performance layer 4 with irule SNAT where i have some SNAT List (IP Address Server SMTP), it is integrate to some SNAT POOL, for example, I have server SMTP notification events to clients, the Snat Pool List have ip address server SMTP 10.10.10.1 and the outgoing of traffic SMTP is with SNAT Pool with some IP Address "192.168.1.1(A), 192.168.1.2(B), 192.168.1.3(C), 192.168.1.4(D)", my question is:

 

When the server SMTP send email to one client, what is the behavior of the traffic, the email will send for 192.168.1.1 or 192.168.1.2 or 192.168.1.3 or 192.168.1.4? if i send multiple email to client, what is the order of assignment of ip address public for the email traffic outgoing? A next B next C and next D? The order of the configuration SNAT Pool is import? the use of the IP Address is A, B, C and D or the use is any ip address, for example D, C, A and B?

 

Please, can somebody help me?.

 

thanks

 

application delivery
LTM
snat
  • youssef1's avatar
    youssef1
    Icon for Cumulonimbus rankCumulonimbus
    Jun 18, 2018

    Hi Edward,

     

    As explain in this KB link text. The BIG-IP system load balances SNAT pool connections between members using the least connections algorithm.

     

    So in your case, suppose you have this 4 memebers in you snat pool:

     

    • 192.168.1.1(A) --> 6000 connections
    • 192.168.1.2(B) --> 6001 connections
    • 192.168.1.3(C) --> 6002 connections
    • 192.168.1.4(D) --> 6003 connections

    F5 will LB Outgoing smtp connection using least connections. So int the example that I showed you above, the next IP that will be use is A.

     

    Hope it's clear, let me know if you need more details.

     

    Regards