How a hardware device discovers the MAC address of another in the event that it is unknown?

Question

As data packets are moved from one network hardware device to another over a network, hardware address (MAC adresses) come into play? So how a hardware device disovers the MAC addrss of another in the event that it is unknown.

Answer 1

Data packets are split into 8 parts. the first part is called the Header. This part contains the MAC address of the sending unit as well as other information.

It is an automatic process.

Answer 2

MAC---Media Access Control addresses are unique and no two are the same. They are used to identify network hardware nodes. The NIC card or network adapter.

Each MAC address has six octets, with each octet consisting of one byte, each byte has eight bits. The eight bits are sperated into groups of two, which are represented by hexidecimal format.

While the human readable format is the hexidecimal format, each MAC address is sent across the network in a series of ones and zeros. With the most important bytes first, and the least important byte last.

The manner is which these addresses are created identifies the company which manufactured the adapter. This is conveyed in the first octet of the MAC address. Dell, HP, and many other companies are easily recognized via this format.

A MAC address is not unknown. While we may not know who the user is at the other end, the actual adapter is always identified, and can be determined who manufactured it, and which actual physical device lot it is, by the serial number it contains. An adapter can therefore be easily discovered not only by the network protocols MAC address translation, but also by anyone who knows how to decode the bytes and use the IEEE's charts to discover who manufactured it. At which point an investigater could contact the store, and find out exactly when it was sold, and sometimes even to who.

I only include that information so you can see that every single MAC address is known. The hardware device itself does not "discover" the MAC addresses of other hardware devices, that is done by the Networking Protocol.

The modem, router or other network translation devices are what use the different network translations to know which device to send data packets to. The adapter simply sends and recieves, it doesn't actually do any discovering.

Each system has networking capabilities, which is why we can create an Adhoc network, or a network between devices which does not include an Internet connection. Just a simple connection between devices which allows for sharing of data. In this scenario, the small networking capabilities uses the MAC address to know where to send data.

This is a very complicated issue. It is far too difficult to explain it here. Here is some resources where you can read up and get a good idea how it all works. It can be a bit of dry reading if you are not particularily interested in the details, but for me it is fun reading and can consume a great deal of my time. lol

http://en.wikipedia.org/wiki/MAC_address

There are additional links at the bottom of the page which you may find very interesting and which can give more information. Also, put Address Translation into the search box and you will find a ton of informational sites.

Answer 3

Through the IP address and a protocol called ARP (Address Resolution Protocol).

If your interested in more check out the link.