How ARP Cache Work in linux?












0















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



























    0















    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

























      0












      0








      0








      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














      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












      share










      share



      share










      asked 2 mins ago









      AbdAllah TalaatAbdAllah Talaat

      535




      535






















          0






          active

          oldest

          votes











          Your Answer








          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "106"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: false,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: null,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f499207%2fhow-arp-cache-work-in-linux%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          0






          active

          oldest

          votes








          0






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes
















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Unix & Linux Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f499207%2fhow-arp-cache-work-in-linux%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          CARDNET

          Boot-repair Failure: Unable to locate package grub-common:i386

          濃尾地震