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IEEE 802.3: 1 Mb/s=10^6 b/s?

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KCKtt

Technical User
Oct 27, 2002
3
PL
The IEEE standard 802.3 employs "Mb/s" (or "Mbit/s"), but I can't find any explicit definition in


I believe that 1 Mb/s means a bit rate of one million bits per second (10^6 b/s), and that it is defined in other standards (possibly in 610.7-1995, although the latter seems to have been withdrawn).

Can somebody give me a precise reference for the definition of 1 Mb/s as used in the current IEEE standards?

Since I can't afford IEEE's fees, I would appreciate very much getting a scan of a suitable fragment of an IEEE publication sent as attachment to my email address, or at least a quotation posted here. Alternatively, maybe somebody could provide a link to an organization that quotes the IEEE definition?

The final part of the NIST page


suggests that, at least since 1997, in IEEE terms, 1 Mb = 10^6 b unless the usage of the binary prefix M = 2^20 is pointed out on a case-by-case basis. If this could be confirmed with a proper reference, it would clarify the meaning of Mb/s as well.

In case you are wondering, I got involved in a heated discussion with computer-science guys, who say they won't believe that 1 Mb/s = 10^6 b/s in data transmission rates until I show appropriate standards. Well, even one CISCO engineer keeps saying that 1 Mb/s = 2^20 b/s, contrary to CISCO's definitions of Mbps.

I may be missing something obvious, so I would appreciate any help, including pointers to other groups if this one is not appropriate.
 
Having worked in this business for many years, I can say with confidence that 1Mb/s is 10^6 or 1,000,000 bits per second in the transmission world. Not being a computer science guy, I'm curious as to the significance of 2^20? Sometimes data folks and comm folks fail to communicate because data geeks tend to think in bytes/second whereas comm geeks always think in bits/second. I can't count the number of times someone has complained that they are only getting 1/8th the download rate that they should be. Invariably, it turns out that the download rate is being measure in bytes/second over a bits/sec transmission line.
 
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