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ARP: Difference between revisions
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(Created page with '==Linux ARP states== {|class="wikitable" border="1" !state !meaning !transitions |- |'''permanent''' |never undergoes verification or expiry |none (manually configured) |- |'''no…') |
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|still usable, needs verification | |still usable, needs verification | ||
|use resets timer and returns to '''reachable''' | |use resets timer and returns to '''reachable''' | ||
timer changes state to delay | timer changes state to '''delay''' | ||
|- | |- | ||
|'''delay''' | |'''delay''' | ||
|schedule ARP request, needs verification | |schedule ARP request, needs verification | ||
|use resets timer and returns to '''reachable''' | |use resets timer and returns to '''reachable''' | ||
timer changes state to probe, issuing ARP request | timer changes state to '''probe''', issuing ARP request | ||
|- | |- | ||
|'''probe''' | |'''probe''' | ||
|need ARP reply for verification | |need ARP reply for verification | ||
|use resets timer and returns to '''reachable''' | |use resets timer and returns to '''reachable''' | ||
timer reissues ARP requests or moves to failed | timer reissues ARP requests or moves to '''failed''' | ||
|- | |- | ||
|'''incomplete''' (new entry) | |'''incomplete''' (new entry) | ||
|need ARP reply for first use | |need ARP reply for first use | ||
|use resets timer and returns to '''reachable''' | |use resets timer and returns to '''reachable''' | ||
timer reissues ARP requests or moves to failed | timer reissues ARP requests or moves to '''failed''' | ||
|- | |- | ||
|'''failed''' | |'''failed''' | ||
Revision as of 09:14, 19 July 2011
Linux ARP states
| state | meaning | transitions |
|---|---|---|
| permanent | never undergoes verification or expiry | none (manually configured) |
| noarp | normal expiration, never verified | use resets use counter |
| reachable | normal expiration | use resets timer |
| stale | still usable, needs verification | use resets timer and returns to reachable
timer changes state to delay |
| delay | schedule ARP request, needs verification | use resets timer and returns to reachable
timer changes state to probe, issuing ARP request |
| probe | need ARP reply for verification | use resets timer and returns to reachable
timer reissues ARP requests or moves to failed |
| incomplete (new entry) | need ARP reply for first use | use resets timer and returns to reachable
timer reissues ARP requests or moves to failed |
| failed | no response received | timer governs reissuing of ARP requests
use resets timer and moves to reachable |
See Also
- "The ARP State Machine" James Westall's CpSc 853 "Protocol Implementation" class notes
- "2.1 Address Resolution Protocol (ARP)" Martin Brown's "Guide to IP Layer Network Administration with Linux"
