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How to calculate storage for Log Collector for CGNAt log session?

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  • 1.  How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-10-2018 20:19

    Hi all,

     

    May i know whether someone can share the formula how to calculate space of storage need on Syslog/Log Collector for CGNAT session. Let's say the total suscriber is 3 million. Not sure whether url below is can use or juniper have their own formula calculation.

     

    https://tools.ietf.org/id/draft-nishizuka-cgn-deployment-considerations-00.html

     

    Thanks and appreciate someone feedback



  • 2.  RE: How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-10-2018 23:36

    Hello,

    AFAIK,  JNPR-proprietary calculation formula does not exist and You can use algorithm described in the cited Internet Draft.

    You can get the exact raw syslog messages sizes and session establishment/teardown rates (if You are using NAT44) or PBA block allocation/release rates (if You are using PBA) from Your own lab or production.

    And AFAIK, JNPR does not sell syslog compression products but others do (F5 comes to mind).

    HTH

    Thx

    Alex



  • 3.  RE: How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-10-2018 23:56

    Hi aaserniv,

     

    Just want to get advise from u, when i look into that url i'm not see the value "a" stand for what thing. Do u know how they can get value  6.4 TB per day?

     

    "It should be noted that the log is generated at the timing of NAT table creation and freeing. As the result, for 1,000,000 users, the size of log is piled up to 6.4 terabytes per day"

     

    The size of log (L) = # of Subscriber (S) * a * N * 120byte * 2 * ( Time frame(T) / 5 min. )

     

    Thanks and appreciate any help.



  • 4.  RE: How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-11-2018 00:13

    Hello,

    My reverse calculation shows that value of a* N = 101.8.

    Explanation: 

    6.4TB is approximately 7036874417766 bytes

    There are 288 5-min intervals in the 24-hour period.

    1,000,000 * a * N * 120 * 2 * 288 = 7,036,874,417,766

    a * N = 101.8

    My educated guess is that N is 400 and a is the compression factor (~0.25 in this case).

    HTH

    Thx

    Alex



  • 5.  RE: How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-11-2018 00:29

    Hi aarserniv,

     

    Please teach me how u get value of "a". On your calculation

     

    a * N = 101.8    and value N = 400 but what is value "a".

     

    Thanks and appreciate your guidance.



  • 6.  RE: How to calculate storage for Log Collector for CGNAt log session?
    Best Answer

    Posted 10-11-2018 01:40

    Hello,

    My math tells me

    if a * N = 101.8

    and

    N = 400,

    then

    a = 101.8/400=0.25.

    HTH

    Thx
    Alex



  • 7.  RE: How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-11-2018 02:20

    Hi Aarserniv,

     

     

    So the value "a" u get is "0.25" that referring to compression. So that 0.25 is can used if number of suscriber change? Lets say 2m suscriber.

     

    Thanks



  • 8.  RE: How to calculate storage for Log Collector for CGNAt log session?

    Posted 10-11-2018 02:57

    Hello,

     


    @kronicklez wrote:

     

     

    So that 0.25 is can used if number of suscriber change? Lets say 2m suscriber.

     

     


     

    My another educated guess is that "a" is constant for a given log compressing device and does not depend on the subscriber count since log reformatters/compressors deflate every single syslog message individually (basically, cut & discard unnecessary fields and translate IP+timestamp ASCII records into binary) and do not "learn" patterns across other messages, as other popular algos like LZH do.

    HTH

    Thx

    Alex