Re: Long distance links
Rich,
I should have said 300m MMF short reach would be used quite a bit for the WAN compatible
PHY because of facilities collocation of the NSP systems with the metro and long haul
transmission/DWDM systems. Thank you for correcting my understanding of the current
objective distances.
Thank you,
Roy Bynum
MCI WorldCom
Rich Taborek wrote:
> Roy,
>
> HSSG objectives only specify a MMF distance of 300M. How to you intend to meet the 500M
> distance over MMF when operating at an OC-192 line rate? Do you have a 500M MMF WAN PHY
> proposal available now or to present in York or Kauai?
>
> Note the Lucent has presented a brand new fiber with a bandwidth*distance of 2200/500
> MHz-km at 850/1300 nm with “laser” launch. This is one of the best fibers I know of.
> It'll get you out to about 440M at an OC-192 line rate with VCSEL. Note also that this
> is NEW not INSTALLED fiber.
>
> In my estimation, if you want an inexpensive 500M MMF interface which connects a
> customers LAN with DWDM equipment, you need to reduce the line rate with a MAS, WWDM,
> or Parallel Optics approach.
>
> Best Regards,
> Rich
>
> --
>
> Roy Bynum wrote:
>
> > Rich,
> >
> > There are two different WAN specific implementation architectures. One of these is
> > to use one of the SMF PHYs. The other uses a MMF PHY. When going into transport
> > DWDM equipment at the customer or ISP POP site, the service providers would like to
> > save money by using inexpensive interfaces also. The 500M MMF PHY is also a WAN
> > implementation.
> >
> > Thank you,
> > Roy Bynum
> > MCI WorldCom
> >
> > Rich Taborek wrote:
> >
> > > Paul Bottorff wrote:
> > >
> > > (text deleted)
> > >
> > > > Provided people built networks to this configuration, then it works just
> > > > fine.
> > > > The IEEE has not yet decided to build 2 PHYs. I believe that the WAN PHY
> > > > being talked about does not have a distinct identity from the LAN PHY.
> > > > Because I don't have a good criteria for distinct identity I've found no
> > > > reason to believe the committee should build 2 PHYs. My assumption is that
> > > > any PHY developed may run on SMF and may be deployed in the wide area. This
> > > > is what is currently happening with 1 GigE.
> > >
> > > (text deleted)
> > >
> > > Paul,
> > >
> > > This is exactly what I'm concerned about. Your requirements to have Ethernet
> > > operate at a MAC/PLS rate of 9.58464 Gbps, perform encoding with NRZ efficiency
> > > (assumed to mean 0% overhead) and not use special symbols is unreasonable and
> > > in conflict with virtually all 10 GbE PHY proposals presented to the HSSG to
> > > date.
> > >
> > > The best criteria for distinct identity is cost. For example, we can go through
> > > all the components in a MAS PHY and all the components in your proposed WAN PHY
> > > if you like. ...All right... I'll tell you: A prototype MAS PHY transceiver I
> > > envision will use an SFF shell, a SFF connector, a MAS PHY CMOS chip including
> > > laser driver, one laser, one photodiode/aIA/Post-amp and operate at 5 GBaud
> > > (2.5 GHz). The result will be a significant difference in cost with a MAS PHY
> > > coming out on top.
> > >
> > > Another criteria is distance. A MAS PHY at 5 GBaud will support a MMF (all LANs
> > > are MMF not SMF) distance of approximately 2X your proposed WAN PHY given the
> > > same optics (which BTW need to support half the bandwidth of a WAN PHY and are,
> > > therefore, less expensive.
> > >
> > > Another criteria is ease of implementation through the use of integral clock
> > > multiples in the most common 10 GbE equipment. That is, equipment which
> > > supports multiple Ethernet data rates.
> > >
> > > I could go on...
> > >
> > > Many PHYs proposed for 10 GbE WILL NOT run over SMF. I'm probably splitting
> > > hairs here, but VCSELs in general support only MMF. Many of the 10 GbE PHY
> > > proposals support VCSELs. Are you excluding VCSELs from supporting 10 GbE?
> > >
> > > I participated in the Gigabit Ethernet Standards process from day 0 till the
> > > standard was published. There was never an objective set to support the WAN nor
> > > was there any discussion or work done on a separate WAN PHY. As you and Roy
> > > Bynum have pointed out, GbE is being successfully deployed in the WAN without
> > > even considering this environment. I'm wondering right now if the HSSG should
> > > do the same at 10 GbE?
> > >
> > > Your proposal for a single PHY to meet all HSSG objectives including direct
> > > support of the SONET WAN environment appears to be flawed from both a
> > > cost/performance and simplicity perspective. 802.3 folks have drummed these
> > > basic tenets into my head since I joined the group trying to sell them Fibre
> > > Channel technology lock stock and barrel. I clearly changed my tune, proving my
> > > flexibility. We can start negotiating any time now :-)
> > >
> > > > Paul A. Bottorff, Director Switching Architecture
> > > > Enterprise Solutions Technology Center
> > > > Nortel Networks, Inc.
> > > > 4401 Great America Parkway
> > > > Santa Clara, CA 95052-8185
> > > > Tel: 408 495 3365 Fax: 408 495 1299 ESN: 265 3365
> > > > email: pbottorf@xxxxxxxxxxxxxxxxxx
>
> -------------------------------------------------------------
> 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: rtaborek@xxxxxxxxxxxxxxxx
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> Palo Alto, CA 94303-4305 Alt email: rtaborek@xxxxxxxxxxxxx