IEEE: Mbit/s... or Mibit/s?

[Godigo]

Hi!

Does anyone know for certain if protocol IEEE 802.11 ou IEEE 802.3 megabits are with decimal SI prefix ou binary prefixes?

Example:

Decimal prefix: 1 megabit = 1.000.000 bits

Binary prefix: 1 megabit = 1.048.576 bits

(I'm aware of binary prefix Mibi, Kibi, etc. The discussion is not about that.)

Rule of thumb is that in networks is the Decimal notation that prevails, but in the IEEE 100 dictionary (2000 edition), they refer megabit with binary notation. I'm extremely confused...


Regards,

Rodrigo Selada

[RadioRaiders]

Hmmm...interesting question. I would say binary, since bits are binary digits and should be measured as so. I think the decimal notations are just used to round it. It's easier to say 1 Megabit, instead of "one million and fourty-eight thousand bits", right? ...and the difference in practical terms isn't really much either. I work in telecom networks, and in transmission we always refer to a E1 line as a 2 Mb line, even tho it's technically 2048 Mbits.

...here's what Wikipedia says, if it helps. My interpretation is that even with decimal notation, it still implies implies binary (1kb=1048 bits).

Binary prefix - Wikipedia, the free encyclopedia

The dual use of these prefixes as both decimal and binary quantities was defined in standards and dictionaries. The 1986 ANSI/IEEE Std 1084-1986[17] defined dual uses for kilo and mega.

kilo (K). (1) A prefix indicating 1000. (2) In statements involving size of computer storage, a prefix indicating 210, or 1024.

mega (M). (1) A prefix indicating one million. (2) In statements involving size of computer storage, a prefix indicating 220, or 1,048,576.

The binary units Kbyte and Mbyte were formally defined in ANSI/IEEE Std 1212-1991.[18] The terms Kbyte, Mbyte, and Gbyte are found in the trade press and in IEEE journals. "Gigabyte" was formally defined in IEEE Std 610.10-1994 as either 1,000,000,000 or 230 bytes.[19] Kilobyte, Kbyte, and KB are equivalent units and all are defined in the current standard, IEEE 100-2000.[20]

With Gigabytes, it's just saying a million bytes. A byte is still 8 bits, and therefore still binary.

[Godigo]

Thank you, RadioRaiders

Even so, I'm reticent to be sure that is decimal notation.

Usually, I see the rule:

• Data storage and network: Decimal notation (Even if file managers usually show as binary)
• Memory: Binary notation (is a must for computers)

I've had read a lot of wikipedia articles, but not the one you showed. Your deduction makes sense from the data you read, but I also read (Gigabyte: Definition - Wikipedia)

There are two different definitions of gigabyte in general use:

• 1,000,000,000 bytes or 109 bytes is the decimal definition, used in telecommunications (such as network speeds) and most computer storage manufacturers (such as hard disks and flash drives). This usage is compatible with SI. Quote from Seagate: "For drive storage capacity, 1 gigabyte = 1,000,000,000 bytes (or one billion bytes).",[2] Similar quotes are found on the websites of other storage manufacturers.
  
  
• 1,073,741,824 bytes, equal to 10243, or 230 bytes. This is the definition commonly used for computer memory and file sizes. Microsoft uses this definition to display hard drive sizes,[3] as do most other operating systems and programs by default. By this definition, there are 1,0243, or 1024×1024×1024 bytes in a gigabyte. (This is equivalent to 1,024 megabytes, where one megabyte is 1,048,576 bytes or 220 bytes.) Since 1999, the IEC recommends that this unit should instead be called a gibibyte (abbreviated GiB).

which says that is decimal for storage and network and binary for memory (sigh). But this text has no reliable references...

I would like to see more opinions... or the unquestionable reference... maybe from a IEEE 802 member :-P (The IEEE 802.* document standards say nothing about this)

Regards,
Rodrigo

[RadioRaiders]

Yea, confusing, eh? I just say over-dimension everything and don't worry about it

By the way: where does 220 come from?

one megabyte is 1,048,576 bytes or 220 bytes

[Charlyee]

Originally Posted by RadioRaiders

Yea, confusing, eh? I just say over-dimension everything and don't worry about it

By the way: where does 220 come from?

Isn't that base 20 base 2 or 2 to the power of 20, which equals to 1,048,576?

Same as 30 base 2 or 2 to the power of 30.equals to 1,073,741,824

[RadioRaiders]

Originally Posted by Charlyee

Isn't that base 20 base 2 or 2 to the power of 20, which equals to 1,048,576?

Oh yea, Ok. The way it was typed confused me. The 20 should be raised in an exponential way.

[Ddeere2]

But 802.11 is for wireless specs, it has nothing to do with 802.3 or data rates.


IEEE 802.11 - Wikipedia, the free encyclopedia

IEEE 802.11 is a set of standards for wireless local area network (WLAN) computer communication, developed by the IEEE LAN/MAN Standards Committee (IEEE 802) in the 5 GHz and 2.4 GHz public spectrum bands.

I would think its in binary. I never really stopped and thought about this and it never came up in my CCNA class. I would say its binary because as with routing, everything refers back to binary.

[Godigo]

RadioRaiders,
I also stopped to think when I read your text... because it also had "220". Only when I read the Wikipedia page I got it :-)

I could overdimension :-P but I'm doing measurements in my Master thesis that I want to be rigorous (that's why I haven delivered, yet :-|). I think the application I use (MGEN & TRPR) uses decimal.


Ddeere2,
I understand... but I think that routing and quantifying data are not necessarily seen in the same way.


Well... a so everyday thing that anyone knows the answer. So strange


Thanks.

Regards,
Rodrigo

[Godigo]

Oh,

Originally Posted by Ddeere2

But 802.11 is for wireless specs, it has nothing to do with 802.3 or data rates.

I know that... both 802.3 and 802.11 have Mbit/s specifications. The standards were only to help explain the question.


Rodrigo