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Cache Table

Cache Table. ARP Modules. Output Module. Sleep until IP packet is received from IP Software Check cache table for entry corresponding to the destination of this IP packet If (found) If (the state = RESOLVED) Extract the value of the hardware address from the Entry

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Cache Table

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  1. Cache Table

  2. ARP Modules

  3. Output Module • Sleep until IP packet is received from IP Software • Check cache table for entry corresponding to the destination of this IP packet • If (found) • If (the state = RESOLVED) • Extract the value of the hardware address from the Entry • Send the Packet and hardware address to data link layer • Return • If (the state = PENDING) • Enqueue the packet to the corresponding queue • Return • If (not found) • Create a cache entry with state= PENDING and ATTEMPT =1 • Create a queue • Enqueue the packet • Send ARP request • Return

  4. Input Module • Sleep until ARP packet (request or reply) arrives • Check cache table for entry corresponding to this ARP packet • If (found) • Update the entry ( Set TIME_OUT, Set corresponding Hardware @) • If (state = PENDING) • While (the queue is not empty) • Dequeue one Packet • Send the packet and the Hardware address to the data link • If (not found) • Create an entry • Add the entry to the table • If (the packet is a request) • Send an ARP reply • Return

  5. Cache Control Module • Sleep until the periodic time matures • For every entry in the cache table • If (State = free) • continue • If (the state = PENDING) • Attempt++ • If (Attempt > Maximum) • State = Free • Destroy the corresponding queue • Else • Send an ARP request • Continue • If (the state = RESOLVED) • TIME_OUT = TIME_OUT – ELAPSED_TIME • If (TIME_OUT < 0) • The State = Free • Destroy the corresponding queue • Return

  6. Cache Table (after 20 sec)

  7. Cache Table (15 sec later)

  8. Cache Table (after 25 sec)

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