Curiosity question on MAC address


R

richard

I"ve always wondered how the manufacturer determines what the mac address
is going to be.
Is there some sort of agreed upon format to identiify the manufacturer?
Like a VIN is for the automobile?
From what I see, mine is a 6 digit hexa decimal number.
eg: 00-11-22-33-44-af

After a million computers, the numbers would be repeated.
 
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G

Ghostrider01

I"ve always wondered how the manufacturer determines what the mac address
is going to be.
Is there some sort of agreed upon format to identiify the manufacturer?
Like a VIN is for the automobile?
From what I see, mine is a 6 digit hexa decimal number.
eg: 00-11-22-33-44-af

After a million computers, the numbers would be repeated.
There is a standard format, as indicated. As for how many MAC's
can be issued, remember that the number is in hex with each pair
having 70 (alpha & numeric) combinations and each set of 6 having
the possibility of 5 different permutations. (I think I got this
right regarding combinations and permutations.) That could cover
all of the communication devices used in digital electronics.

GR
 
K

Ken1943

I"ve always wondered how the manufacturer determines what the mac address
is going to be.
Is there some sort of agreed upon format to identiify the manufacturer?
Like a VIN is for the automobile?
From what I see, mine is a 6 digit hexa decimal number.
eg: 00-11-22-33-44-af

After a million computers, the numbers would be repeated.
This address my help you understand

http://www.adminsub.net/mac-address-finder

The first three groups xx:xx:xx are the vendor and there can be up to 48
groups = billions


KenW
 
E

Evan Platt

I"ve always wondered how the manufacturer determines what the mac address
is going to be.
Is there some sort of agreed upon format to identiify the manufacturer?
Like a VIN is for the automobile?
Yes. Google it.
From what I see, mine is a 6 digit hexa decimal number.
eg: 00-11-22-33-44-af

After a million computers, the numbers would be repeated.
Math fail.

There are 281474976710656 possible combinations of numbers.
 
J

John Williamson

Evan said:
Yes. Google it.


Math fail.

There are 281474976710656 possible combinations of numbers.
Even if they weren't hex, there would be (10^12 -1) valid combinations,
assuming 0 is not a valid value. That's a million million, near enough.
 
K

Ken1943

Even if they weren't hex, there would be (10^12 -1) valid combinations,
assuming 0 is not a valid value. That's a million million, near enough.
In other words "heck of a lot"


KenW
 
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G

Gene E. Bloch

There is a standard format, as indicated. As for how many MAC's
can be issued, remember that the number is in hex with each pair
having 70 (alpha & numeric) combinations and each set of 6 having
the possibility of 5 different permutations. (I think I got this
right regarding combinations and permutations.) That could cover
all of the communication devices used in digital electronics.

GR
Wow. You missed it. If you did it the easy way, you'd get it right.

First, digits 0-9 and A-F define 16 values (same as 4 bits), so each
pair has 256 possible values, not 70.

Anyway, a *much* easier way to look at it (IMO): there are 12 hex
digits, each representing 4 bits, so the MAC address represents a 48-bit
binary number.

Thus the possible values are 0 to (2^48 - 1), or 0 to about 2.81x10^14
(AKA 2.81E14).

The current human population of the earth is about 7x10^9.
 
R

richard

Even if they weren't hex, there would be (10^12 -1) valid combinations,
assuming 0 is not a valid value. That's a million million, near enough.
hex=16
16*16=256
256*6=1,536

how do you get your total?

So why would you need 3 pairs to identify the manufacturer when there
aren't even 50 manufacturers?
 
K

Ken1943

hex=16
16*16=256
256*6=1,536

how do you get your total?

So why would you need 3 pairs to identify the manufacturer when there
aren't even 50 manufacturers?
Don't know, but that web site I posted shows it. A Google search shows a
lot of information.


KenW
 
K

Ken1943

hex=16
16*16=256
256*6=1,536

how do you get your total?

So why would you need 3 pairs to identify the manufacturer when there
aren't even 50 manufacturers?
Put another way, there are so many possible addresses that the world
don't have enough fingers!! LOL


KenW
 
K

Ken1943

hex=16
16*16=256
256*6=1,536

how do you get your total?

So why would you need 3 pairs to identify the manufacturer when there
aren't even 50 manufacturers?
I haven't used mathematical progression in many years.


KenW
 
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E

Evan Platt

So why would you need 3 pairs to identify the manufacturer when there
aren't even 50 manufacturers?
Because the first 3 octets identify the manufacturer, that's why you
need the first 3 octets.
 
P

Paul in Houston TX

richard said:
hex=16
16*16=256
256*6=1,536

how do you get your total?

So why would you need 3 pairs to identify the manufacturer when there
aren't even 50 manufacturers?
At this time there are about 18,000 mfgs. I bet in another 10 years
that list will double. Everthing is getting embeded comm devices now,
washing machines, light switches, etc.
 
K

Ken1943

At this time there are about 18,000 mfgs. I bet in another 10 years
that list will double. Everthing is getting embeded comm devices now,
washing machines, light switches, etc.
I figured out the mathematical progression, but I don't know how to show
it here. The first two addresses work out to 65,536 and from a search can
go up to 48 addresses = really big number.


KenW
 
R

ray carter

hex=16 16*16=256 256*6=1,536

how do you get your total?
There are 12 digits, base 16. So the total is 16 ** 12 - i.e. 16 raised
to the twelveth power - i.e. 16 multiplied by itself 12 times.
 
R

richard

I figured out the mathematical progression, but I don't know how to show
it here. The first two addresses work out to 65,536 and from a search can
go up to 48 addresses = really big number.


KenW
just use a calculator and mulitp;y 256 times 256 for six times.
ie 16 raised to the power of 6.
 
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K

Ken1943

just use a calculator and mulitp;y 256 times 256 for six times.
ie 16 raised to the power of 6.
I did. Some of my math has gone the way my age did.


KenW
 
S

Stan Brown

There is a standard format, as indicated. As for how many MAC's
can be issued, remember that the number is in hex with each pair
having 70 (alpha & numeric) combinations
Where's you get 70? 00 to FF is 256 combinations.
and each set of 6 having
the possibility of 5 different permutations. (I think I got this
right regarding combinations and permutations.)
Sorry, but no. The number of ways to permute six things is 6! (6
factorial), which is 720.

But that's way too complicated a method. Take a simpler approach:
there are 12 digits, each with 16 possibilities varying
independently, so there are 16^12 possibilities, about 280 trillion
(280 million million if you're in the UK).
That could cover
all of the communication devices used in digital electronics.
Indeed yes.
 
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A

athiker

I"ve always wondered how the manufacturer determines what the mac address
is going to be.
Is there some sort of agreed upon format to identiify the manufacturer?
Like a VIN is for the automobile?
From what I see, mine is a 6 digit hexa decimal number.
eg: 00-11-22-33-44-af

After a million computers, the numbers would be repeated.

All this math make my head hurt.
 

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