Wednesday, May 26, 2010

New age in Ethernet port naming

In less than a month, the IEEE Standards Association (IEEE-SA) Review Committee (aka RevCom) will offer a recommendation to the IEEE-SA Standards Board on the approval of IEEE P802.3ba which is the draft standard for 40 Gigabit and 100 Gigabit Ethernet.  Given that approval is pretty much a slam dunk, the resulting standard IEEE Std 802.3ba-2010 will usher in a new age of Ethernet port naming.

When Ethernet first considered doing fiber optic links back in the 10M and 100M days, they used to just an F to indicate that the medium to use was fiber optic cabling.  Over time, Ethernet speeds have increased, laser technology has improved, and fiber optic cabling has advanced.

When Gigabit Ethernet came into being in 1998, the Ethernet industry hailed in the concept instead of just calling it F for fiber optics that stating the wavelength to be used would help the end user.  1000BASE-SX was a Gigabit Ethernet port that would transmit 8B/10B encoded data using the 850 nm wavelength (short wavelength) on multimode fiber.  The X implied an externally sourced coding scheme (8B/10B came from Fibre Channel), and the S implied short wavelength.  1000BASE-LX would transmit the same data using the 1310 nm wavelength (long wavelength) on either multimode (using a mode conditioning patch cord) or single-mode fiber.

When 10 Gigabit Ethernet came into being in 2002, the Ethernet industry continued the support of that concept.  10GBASE-SR was a 10 Gigabit Ethernet port that would transmit 64B/66B encoded data - the R was used to give credit to the inventors of 64B/66B: Rich Dugan and Rick Walker - using short wavelength optics.  10GBASE-LR would use the long wavelength, but the mode conditioning patch cord was such a pain that it was decided to only use LR with single-mode fiber.  10GBASE-ER would transmit the same data using a new "extra long wavelength": 1550 nm.  Later, in 2006, a new port type would be created: 10GBASE-LRM.  Applying the principles previously used, this was 10GBASE-LR device, but with a unique feature; it was tuned to operate directly over multimode fiber, hence the M at the end of the name.

What was interesting is that the marketing types at some of the big switch companies could not understand these tough technical names, so they invented their own.  SR became "short reach", LR became "long reach", ER became "extended reach" and LRM became "long reach multimode".

Sounds like a great translation, doesn't it?  It would work if it was true.  SR can achieve 300 m on OM3 multimode fiber; whereas, LRM can only achieve 220 m.

Guess what, the marketing types won!

With 40 Gigabit and 100 Gigabit Ethernet, SR, LR and ER mean reach, not wavelength.  SR will do 100 m on OM3 with the 850 nm wavelength, LR will do 10 km on single-mode fiber with the 1310 nm wavelength, and ER will do 40 km on single-mode fiber with the 1310 nm wavelength.  In 10 Gigabit Ethernet, an LR and an ER port type could never communicate with each other.  The names were different, the wavelengths were different; therefore, there was no information exchange.  At 100 Gigabit Ethernet, an LR port can talk to an ER port if they are within 10 km of each other.

So, the time has come to unlearn the "technical" terms for Ethernet port name and time to embrace the "marketing" hype.  Heaven knows, it will get interesting if new port types need to be created.

1 comment:

kenmiller said...

Thanks for let us know how the different names were introduced in order to get rid of confusion.

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