Why we need both Logical and Physical addressing in networking?

By Somnath laha ·
Why we need both Logical and Physical addressing in networking?

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by neilb@uk In reply to Why we need both Logical ...

networks are logical and humans are physical.

Or maybe it's the other way round...

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Physical addressing (MAC-level) happens on local media..

by cmatthews In reply to Why we need both Logical ...

..(the wires) within a relatively small geographic area (like a LAN). You could think of this like license plates on cars and trucks on roads in an island country. They carry parcels to and from house's, business's, airports and seaports on the island.

When these parcels (logical packets), go off the island they must use a boat or plane (network gateways or routers) to transfer their payload to another destination based on logical addressing.


Physical Example:
Ethernet - Xerox invented it in the 70's and used 6-byte addresses and other device manufacturers were assigned ample ranges. This made it so no one would really ever have to worry about making cards with the same physical address twice. A good byproduct we take for granted is that our LAN's usually run fine from the physical addressing perspective.

Logical example:
IP addresses can be dynamically (DHCP) or statically assigned. When a PC gets an IP address by DHCP and is now running when a second PC with a static IP boots up, then you have a conflict. (usually the first station continues, while the second pulls away). The internet is now running-out of IP addresses since there are only 4 bytes used - this is why some think when IP version 6 arrives, the Internet will segment.

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