A R P & R A R P summary
ARP protocol is playing an important role amid the Internet layer of the TCP/IP suite.
It allows knowing the network board physical address corresponding to the IP address.
That’s the reason why it is called Address Resolution Protocol.
Every connected computer to the network has an identification number.
It is unique and given when the interface is made.
However this number is not directly used to communicate on the internet.
There is a logical address used for it, which is given by a world wide company managing this attribution.
So, to fill in its corresponding tables, ARP asks the connected computers their identification numbers, then create the table with the correspondences between the identification numbers and the logical addresses.
This table is written in a memory cache.
While a computer is trying to communicate within the network, if the address is not in the table, ARP send a request, if a connected computer has the right address, by answering and sending its identification number and ip address, ARP can store the couple of addresses in the table then the communication begins.
RARP protocol (Reverse Address Resolution Protocol) is not used very much.
It is a kind of reverse phonebook for physical and logical addresses.
It is only useful for working stations with no hard drive that need to know their physical addresses.
It allows a working station knowing a ip address from a correspondence table between MAC address and ip address owned by a getaway connected to the same LAN network.
To do so, the administrator must configure the getaway with the correspondence table.
Unlike ARP, RARP this protocol is static.
So you must update the table in order to allow all new stations to communicate.
RARP is a very limited protocol.
It needs a lot of administration time to keep the tables updated.
It is even truer for bigger networks.
The team managing these networks has to be well numbered to maintain the tables.
If you still need that kind of protocol, you can improve the updates by using the dynamic version called DRARP.
You can also used DHCP to manage dynamically the addresses.