Just what is Ethernet?

Gary is right: “… ‘Ethernet’ … no one (possible exception would be network engineers on standards committees or in academia) uses the term for what it really means.”   And I have to add myself to the exception list – must be the engineer part of me.  Precision of nomenclature matters.  Now there’s a marketing part of me, too.  But the goal of the marketing part of me is not to create a story out of nothing, but to communicate the technical underpinnings clearly.  I don’t want to blur Ethernet into what it is not.

Kenna’s concluding paragraph really does try to unblur the definitions: “Clearly, the sources of confusion are many. But remember that Ethernet and TCP/IP are not equals. TCP/IP sits on top of Ethernet.”  I could add that most of the Industrial Ethernet protocols then sit on top of TCP/IP (or as Kenna described it earlier in the article: “The top layer is the applications layer that contains protocol suites…”)  Those protocol suites include  Ethernet/IP CIP, Modbus, and PROFINET.  In addition to sitting on top, PROFINET also includes a real-time stack that sits beside TCP/IP in the OSI model.  (I had to add that last sentence to satisfy the engineer part of me.)

No reason for reluctance in mentioning that there are other Ethernet-based industrial networks, Gary.  We certainly know they’re out there.  In fact many of our members are members of the other networks’ organizations in addition to being members of PTO.  Which leads me to concurrence with your conclusion: “So the market will actually decide. And what the market will decide is that there will be two or three leaders with different technologies. People will confuse the technologies–sometimes on purpose. We’ll continue to have material to write about–and have fun doing it.”

PROFINET is clearly one of those leaders.  In my personal opinion, having multiple standards is actually a good thing for the users.  (I’m on record with that opinion here and here.)  And we are definitely having fun writing, speaking, and training about this stuff!

A final plug for the PROFINET book(let):  Yes, it is mainly about PROFINET, but it also includes some diagrams in the Glossary that help show the OSI model and the Industrial Ethernet model.