How ARP Cache Work in linux?

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-1















I Know the ARP protocol uses and the role of the cache but I have difficulty
understanding the difference between various states of the entries in the ARP Cache like : permanent , noarp , reachable , stale .



I have found the following text explaining them :




The permanent state indicates a valid entry that can only be deleted
manually, the noarp state designates a valid entry that expires at the
end of its lifetime, the reachable state shows a valid entry that
expires when its reachability timeout expires, and the stale state
specifies a valid but suspicious entry.




but I have some difficulty understanding the difference between the meaning of terms like "lifetime" vs "reachability timeout" , "valid" vs suspicious .



I feel the existence of counters/timers in the mechanism and a state diagram but can't figure out the essential documentation source that
explain the mechanism after googling that, so it will be appreciated
mentioning the source documentation I was supposed to search into or
read from .



Thanks










share|improve this question


























    -1















    I Know the ARP protocol uses and the role of the cache but I have difficulty
    understanding the difference between various states of the entries in the ARP Cache like : permanent , noarp , reachable , stale .



    I have found the following text explaining them :




    The permanent state indicates a valid entry that can only be deleted
    manually, the noarp state designates a valid entry that expires at the
    end of its lifetime, the reachable state shows a valid entry that
    expires when its reachability timeout expires, and the stale state
    specifies a valid but suspicious entry.




    but I have some difficulty understanding the difference between the meaning of terms like "lifetime" vs "reachability timeout" , "valid" vs suspicious .



    I feel the existence of counters/timers in the mechanism and a state diagram but can't figure out the essential documentation source that
    explain the mechanism after googling that, so it will be appreciated
    mentioning the source documentation I was supposed to search into or
    read from .



    Thanks










    share|improve this question
























      -1












      -1








      -1








      I Know the ARP protocol uses and the role of the cache but I have difficulty
      understanding the difference between various states of the entries in the ARP Cache like : permanent , noarp , reachable , stale .



      I have found the following text explaining them :




      The permanent state indicates a valid entry that can only be deleted
      manually, the noarp state designates a valid entry that expires at the
      end of its lifetime, the reachable state shows a valid entry that
      expires when its reachability timeout expires, and the stale state
      specifies a valid but suspicious entry.




      but I have some difficulty understanding the difference between the meaning of terms like "lifetime" vs "reachability timeout" , "valid" vs suspicious .



      I feel the existence of counters/timers in the mechanism and a state diagram but can't figure out the essential documentation source that
      explain the mechanism after googling that, so it will be appreciated
      mentioning the source documentation I was supposed to search into or
      read from .



      Thanks










      share|improve this question














      I Know the ARP protocol uses and the role of the cache but I have difficulty
      understanding the difference between various states of the entries in the ARP Cache like : permanent , noarp , reachable , stale .



      I have found the following text explaining them :




      The permanent state indicates a valid entry that can only be deleted
      manually, the noarp state designates a valid entry that expires at the
      end of its lifetime, the reachable state shows a valid entry that
      expires when its reachability timeout expires, and the stale state
      specifies a valid but suspicious entry.




      but I have some difficulty understanding the difference between the meaning of terms like "lifetime" vs "reachability timeout" , "valid" vs suspicious .



      I feel the existence of counters/timers in the mechanism and a state diagram but can't figure out the essential documentation source that
      explain the mechanism after googling that, so it will be appreciated
      mentioning the source documentation I was supposed to search into or
      read from .



      Thanks







      linux linux-kernel arp






      share|improve this question













      share|improve this question











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      share|improve this question










      asked Feb 7 at 3:14









      AbdAllah TalaatAbdAllah Talaat

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