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Re: Proposed WAN vs. LAN Terms (Ethernet HSSG)


My comments are interspersed in your note. wrote:
> Hi All,
> Just a quick question, is there a "term" defined for the very long reach version
> of 10GEth?  These definitions seem to be important to our discussion.  As Brian
> from HP stated, we're not being clear on the specific application environment.
> I'd suggest something like:
> 10,000Base-SX
>         Multi-mode
>         Wavelength ~ 850nm
>         I'd guess WWDM only

1) The CFI WWDM presentation did not "push" SX due to 110 m distance
2) MAS can support SX but more work is required on VCSEL linearity
3) This is the primary variant of Parallel Optics

>         300m reach over 62.5um fiber

MAS is the only scheme that has a chance of attaining 300 m  over 62.5
um on SX

> 10,000Base-LX
>         Single-mode (maybe also multi-mode)

Definitely includes multimode

>         Wavelength ~ 1310nm or 1550nm
>         WWDM, Serial or MAS
>         10km reach

Several sources from whom I've been gathering requirements indicate that
15 km would cover all (+99 %) LAN and carrier access applications

> 10,000Base-EX   (EX=Extended Length)
>         Single-mode
>         Wavelength ~ 1550nm
>         DWDM or Serial

MAS should be included in the above list

>         Externally modulated

MAS does not require external modulation

>         Long Reach
>         (similar to what Bill St. Arnaud is talking about)
> Also, I've seen some comments on the serial version of the 10,000Base-LX that
> assume it'll be externally modulated.  I've heard a number of individuals state
> that a directly modulated 10 Gb laser is possible.  Lucent seemed to be
> proposing this at the Austin meeting (I believe their eye pattern was from one
> of these devices).  If this was a directly modulated uncooled DFB without
> isolator, then I believe it would be by far the lowest cost and the most
> straight forward. Regarding the 10,000Base-EX, I'd (obviously) assume that this
> was only externally modulated.

There is a substantial cost difference between a laser and supporting
PHY electronics which operate in at the frequencies required to support
Serial TDM and MAS to support transport Ethernet packets @ 10 Gbps.
Granted, there is a difference in complexity between these two schemes.

> Regards,
> Bryan Gregory
> 630/512-8520


Best Regards,

Richard Taborek Sr.    Tel: 650 210 8800 x101 or 408 370 9233       
Principal Architect         Fax: 650 940 1898 or 408 374 3645
Transcendata, Inc.           Email: 
1029 Corporation Way     
Palo Alto, CA 94303-4305    Alt email: