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Romain_DA_ROIT_'s avatar
Romain_DA_ROIT_
Icon for Nimbostratus rankNimbostratus
Aug 12, 2015

Source Port reuse timer with SNAT automap

Hi,

 

Using a SNAT automap, is there any specific timer which prevent a source port to not be reused after a closed connection using that same source port ?

 

Romain

 

application delivery
design
LTM
performance

2 Replies

  • Ravi_K__Malhotr's avatar
    Ravi_K__Malhotr
    Icon for Nimbostratus rankNimbostratus
    Aug 12, 2015

    Ah, let me explain this way, covering few basics and interesting to read. 1. upon receiving a request, the Big IP System processes the request, entry added into a connection table. 2. and now the moment connection flow becomes idle, idle connection timer is initiated 3. and when connection reaches the idle session time-out, connection is terminated and also deleted from the connection table.

     

    So, here is an answer for your query --> the same source port will not be used for any other request, if its still there in connection table, either be in active or idle session. once entry is deleted from the connection table, then source port is subject to be re-used.

     

    --Ravi K. Malhotra--

     

  • Romain_DA_ROIT_'s avatar
    Romain_DA_ROIT_
    Icon for Nimbostratus rankNimbostratus
    Aug 12, 2015

    Thanks for your answer. The point is to know if there is any way to set the idle session time-out. Sometimes, the bigip system reuse a source port whereas on the server side, a previous connection with the same source port is still in a TIME_WAIT state. Default TIME_WAIT timer value is set to 60 sec by default (this value can change depending the OS).

     

    I know that using a OneConnect profile may help to manage this situation, but it would be interesting to know the idle session timeout value.