What is ARP ?

  • Its is stands for Address Resolution Protocol.
  • ARP associates an IP address with the physical address.
  • Use to resolve IP Address to MAC addresses.
  • The main Work of the ARP is to convert the 32-bit IP address to 48-bit address.

Mapping of IP Address into Mac Address

  • Static Mapping
    • Table is create with logical and physical Address.
  • Dynamic Mapping
    • Each time a machine knows the logical Address of Another machine.
    • it can use a protocol to find the physical address

Two Different types of APR Entries

  • Dynamic :-
    • Dynamic Entry is create automatically when a device sends out a broadcast message out on the network.
    • Dynamic Entry are not permanent.
    • They are flushed out periodically.
  • Static :-
    • A static Entry is where someone manually enters an IP to MAC address association using ARP Command line utility.
    • A static Entry are often use to reduce any unnecessary ARP broadcast traffic on a network.

The working of ARP protocol

ARP accepts a logical address from the IP protocol, maps the Address to the Corresponding Physical address and pass it to the data link layer.

the working of ARP protocol
The working of ARP protocol

Anytime a HOST or a Router need to find a physical Address of another Host or Router on its network , it sends an ARP Query Packet. The packet Includes the physical and IP address of the receiver. Query is broadcast to the network, when the intended recipient recognizes its IP address , it sends back an ARP response packet which contains both IP and Physical Address.

ARP Packet Format

ARP Packet Format
ARP Packet Format

To know more about Rom please check Wikipedia link click HERE.

Basic Engineer

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