RE: WWDM vs. 10Gb/s serial
- To: "Nader Vijeh" <nader@xxxxxxxxxxxxxx>, <stds-802-3-hssg@xxxxxxxx>
- Subject: RE: WWDM vs. 10Gb/s serial
- From: "Bill St. Arnaud" <bill.st.arnaud@xxxxxxxxxx>
- Date: Mon, 10 May 1999 09:04:57 -0400
- Importance: Normal
- In-Reply-To: <012401be98b6$e9490860$26c5fad0@p6350>
- Reply-To: <bill.st.arnaud@xxxxxxxxxx>
- Sender: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
I think most restoral and protection schemes will move to higher protocol
layers. I don't think the 10xGbE at the PHY layer should be concerned about
fast restoral. However we do need very fast notification of laser failure
on the Tx PHY (< 10 msec) and similarly it would be nice in an ideal world
to have some tools to monitor loss of received laser power (DC bias?) on Rx
PHY . BER would also be useful, but maybe this should be done at a higher
level protocol
Bill
-------------------------------------------
Bill St Arnaud
Director Network Projects
CANARIE
bill.st.arnaud@xxxxxxxxxx
http://tweetie.canarie.ca/~bstarn
> -----Original Message-----
> From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of Nader
> Vijeh
> Sent: Friday, May 07, 1999 2:25 PM
> To: stds-802-3-hssg@xxxxxxxx
> Subject: Re: WWDM vs. 10Gb/s serial
>
>
> The 802.3 standards have always included different PHY options when
> required. Having 2 or more PHY options for trading cost versus distance is
> viable for the LAN, MAN and long haul applications.
>
> What is the group's opinion on framing options for applications where fast
> (<50ms) fault recovery is required?
>
> Nader
>
> -----Original Message-----
> From: Rogers, Shawn <s-rogers@xxxxxx>
> To: 'bill.st.arnaud@xxxxxxxxxx' <bill.st.arnaud@xxxxxxxxxx>;
> BRIAN_LEMOFF@xxxxxxxxxxxxxxxxxxxxxxxxxx
> <BRIAN_LEMOFF@xxxxxxxxxxxxxxxxxxxxxxxxxx>; stds-802-3-hssg@xxxxxxxx
> <stds-802-3-hssg@xxxxxxxx>
> Date: Friday, May 07, 1999 10:23 AM
> Subject: RE: WWDM vs. 10Gb/s serial
>
>
> What if HSSG defined a common fiber module interface for both WDM to serve
> the LAN applications and Serial to serve the WAN applications?
>
> Shawn
> ___________________________________________
> Shawn Rogers, PMP
> s-rogers@xxxxxx
> Wizard Products Program Mgr., Bus Solutions Group
> Texas Instruments, Dallas Texas
> Tel: 972-480-2678, Fax: 972-480-2264 Pager: 972-597-1803
> ___________________________________________
>
>
>
>
> -----Original Message-----
> From: Bill St. Arnaud [mailto:bill.st.arnaud@xxxxxxxxxx]
> Sent: Friday, May 07, 1999 11:17 AM
> To: BRIAN_LEMOFF@xxxxxxxxxxxxxxxxxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> Subject: RE: WWDM vs. 10Gb/s serial
>
>
> I agree 100% with your comments. The requirements of long haul 10xGbE may
> be substantially different than the LAN. But as much as possible I hope
> that the HSSG committee would try to develop solutions that apply
> equally to
> both scenarios for economies of scale etc. Obviously the PHY requirements
> are going to be substantially different, and I agree with you that
> SpectraLAN WWDM seems to make the most sense in a LAN environment
>
> Bill
>
> -------------------------------------------
> Bill St Arnaud
> Director Network Projects
> CANARIE
> bill.st.arnaud@xxxxxxxxxx
> http://tweetie.canarie.ca/~bstarn
>
>
>
>
>
>
>
> > -----Original Message-----
> > From: BRIAN_LEMOFF@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > [mailto:BRIAN_LEMOFF@xxxxxxxxxxxxxxxxxxxxxxxxxx]
> > Sent: Friday, May 07, 1999 12:11 PM
> > To: bill.st.arnaud@xxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> > Subject: RE: WWDM vs. 10Gb/s serial
> >
> >
> > Bill,
> >
> > Again, you are confusing a LAN discussion with an independent, and
> > very different long-haul discussion. I agree wholeheartedly
> > that 10-Gb/s
> > serial, i.e. externally modulated lasers similar to OC-192
> > products are the
> > optimum solution for long-haul, and they are already widely
> > available!
> >
> > The SpectraLAN WWDM proposal is intended to be a low-cost
> > solution for
> > premises and campus LANs (up to 300m on 62.5 micron fiber,
> > up to 10km on
> > single mode fiber). The economics of this market, and the
> > decision between
> > WWDM or serial are completely separate and very different from the
> > long-haul market that you are interested in.
> >
> > Regardless of which market "drives" 10-GbE, different
> > physical solutions
> > will be required for the long-haul and the LAN. Nobody is
> > going to buy a
> > cooled, isolated, externally modulated transmitter, meeting
> > all of the
> > rigorous specs for long-haul transmission, to go 200 meters
> > between wiring
> > closets in an office, or even to go 3km between buildings in
> > a campus.
> >
> > Both LAN and long-haul applications are open for discussion on this
> > reflector. It is important not to confuse the two when
> > making arguments
> > relating to physical layer solutions.
> >
> > -Brian Lemoff
> >
> > ______________________________ Reply Separator
> > _________________________________
> > Subject: RE: WWDM vs. 10Gb/s serial
> > Author: Non-HP-bill!st!arnaud (bill.st.arnaud@xxxxxxxxxx) at
> > HP-PaloAlto,mimegw2
> > Date: 5/7/99 6:51 AM
> >
> >
> > Brian:
> >
> > I disagree with your suggestion that long haul 10xGbE is 6-10 years out.
> > 6-10 months is more likely.
> >
> > Already a "major" ISP has deployed several long haul 1xGbE CWDM
> > systems up
> > to 1000 km in length using a combination of GbE transceivers and
> > optics from
> > Pirelli. In one installation from Quebec city to New York City
> it took 2
> > engineers in a Volkswagon bus 2 days to install this whole system. On a
> > parallel set of fibers a more traditional SONET/DWDM system was
> > installed by
> > the carrier. It took them 3 months and a team of engineers to
> > install that
> > system.
> >
> > The economics of long haul GbE is so compelling that I personally
> > believe it
> > is this marketplace rather than the LAN that will drive 10xGbE
> > development.
> > I know of at least a dozen 1xGbE CWDN long haul systems that are
> > currently
> > being deployed. All of these users would quickly move to 10xGbE
> > if it was
> > available.
> >
> > Several equipment suppliers are shipping CWDM 1xGbE systems that
> > will go as
> > far as 400km
> >
> > In long haul 10xGbE the cost comparison is with SONET, not LAN costs.
> >
> > Bill
> >
> >
> >
> > -------------------------------------------
> > Bill St Arnaud
> > Director Network Projects
> > CANARIE
> > bill.st.arnaud@xxxxxxxxxx
> > http://tweetie.canarie.ca/~bstarn
> >
> >
> >
> >
> >
> >
> >
> > > -----Original Message-----
> > > From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> > > [mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of
> > > BRIAN_LEMOFF@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > > Sent: Thursday, May 06, 1999 9:09 PM
> > > To: bgregory@xxxxxxxxx
> > > Cc: dolfi@xxxxxxxxxxxxxxxx; bill.st.arnaud@xxxxxxxxxx;
> > > stds-802-3-hssg@xxxxxxxx; dolfi@xxxxxxxxxx; twhitlow@xxxxxxxxx
> > > Subject: WWDM vs. 10Gb/s serial
> > >
> > >
> > > I will try to respond to some of Bryan Gregory's remarks
> regarding
> > > CWDM vs. 10-Gb serial. By the way, I will refer to it as WWDM
> > > (SpectraLAN is HP's implementation of WWDM), since CWDM is
> > > apparently
> > > used to refer to 400-GHz spaced telecom systems, and this
> > has caused
> > > some confusion among some people on this reflector.
> > >
> > > First, let me say that I agree that long-term (say 6-10
> > years out) a
> > > low-cost 10-Gb/s serial solution may be the simplest and
> > lowest cost
> > > solution. That having been said, I think that with today's
> > > technology
> > > (and for several years out) WWDM will be the lowest cost and most
> > > useful technology for 10-GbE LAN applications.
> > >
> > > Fiber: A 4 x 2.5-Gb/s WWDM module in the 1300nm band
> > should still
> > > support useful distances of up to 300m on the installed
> > base of 62.5
> > > micron core fiber. The SpectraLAN approach, like 1000LX, will
> > > simultaneously support multimode and single mode
> > applications (up to
> > > 10-km) with a single transceiver. All 10-Gb/s serial
> > > approaches that
> > > have been proposed (excluding multilevel logic) will require
> > > new fiber
> > > to be installed in premises applications.
> > >
> > > Laser Cost: At 2.5-Gb/s, low-cost uncooled, unisolated DFB
> > > lasers can be
> > > used with no side-mode suppression requirement (double moded
> > > lasers are
> > > okay) up to 10km. These lasers are readily available today
> > > in die form at
> > > costs not that much higher than the FP lasers used in
> > > 1000LX. Linewidth,
> > > RIN, and Jitter requirements at 2.5-Gb/s are MUCH easier to
> > > realize with
> > > high yield and low-cost electrical packaging than they are
> > > at 10-Gb/s (not
> > > to mention 12.5 Gbaud). Optical isolation will probably be
> > > required to
> > > achieve the necessary noise and linewidth requirements for a
> > > 10-km, 10-Gb/s
> > > serial link (Lucent presented an unisolated FP solution for
> > > 1km. The data
> > > they showed for a 10km uncooled DFB link required
> > > isolation). Given this,
> > > I believe that the 4 lasers required for WWDM will be many
> > > times lower cost
> > > than the single laser required for serial.
> > >
> > > Optical Packaging Cost: The 1000LX standard has forced
> > > transceiver vendors
> > > to develop low-cost automated alignment and precision die
> > > attach systems
> > > for aligning edge-emitting lasers to single-mode fiber. In
> > our WWDM
> > > solution, we are leveraging such a system to robotically
> > > assemble and align
> > > our 4 lasers and MUX in a fast, low-cost process. On the Rx
> > > side, only
> > > multimode alignment tolerances are required to align the
> > > demux to the
> > > detector array and glue it into place. The mux and demux
> > > optics themselves
> > > are low-cost parts (many times lower cost than a
> > > micro-optical isolator).
> > > The mux is a simple, unpolished, unpigtailed, silica
> > waveguide chip
> > > (several hundred devices on a standard 4" wafer). The
> demux is an
> > > injection-molded plastic optical part, requiring minimal
> > > assembly. This
> > > may sound complicated, but it is not expensive. As we get
> > > further into the
> > > standards discussions, we'll provide more details that
> > > should help convince
> > > the skeptics that this is a realistic and low-cost solution.
> > >
> > > Electronics: WWDM at 2.5-Gb/s per channel works with
> > > existing low-cost Si
> > > electronics. 10-Gb/s serial Tx and Rx IC's will require
> > > processes at least
> > > 4 times faster. Add to this the tighter jitter and noise
> > > requirements, the
> > > poorer performance of dielectric circuit boards, the higher
> > > laser current
> > > requirements (required to push relaxation oscillation
> > > frequencies 4 times
> > > further out), and you have a difficult electrical problem to
> > > solve. The
> > > cost associated with the electronics and electrical
> > > packaging is likely to
> > > be much higher than that for 4ch WWDM for several years.
> > >
> > > Scalability: Bryan made a good point that a 10-Gb/s
> > serial solution
> > > adopted now could be combined with WWDM later to provide
> > even higher
> > > capacity (e.g. 40 Gb/s). Why not adopt the WWDM (4 x 2.5
> > > Gb/s) solution
> > > now, when 10-Gb/s lasers and electronics are still very
> > > expensive, and then
> > > in a few years, increase the channel rate to 10-Gb/s.
> > > Either solution for
> > > 10-GbE is scalable to 40-Gb/s when it is combined with the other.
> > >
> > > Eye-safety: The proposed power budget for SpectraLAN meets
> > > the Class I
> > > eye-safety requirement by a comfortable margin. At 1550nm
> > > it would be even
> > > better, but increased fiber dispersion and the lack of
> > > well-characterized
> > > fiber in the LAN make this a more difficult option. It
> > > should be noted
> > > that 4 lasers means 6-dB less eye-safe power available per
> > > laser, but at 4
> > > times the speed, for a given IC process, a typical receiver
> > > will be less
> > > sensitive by at least 6 dB, negating the eye-safety
> > > advantage inherent in
> > > the serial approach.
> > >
> > >
> > > "Inherent Simplicity": A serial approach is "inherently
> > > simple". The
> > > question which we must answer over the coming year is which
> > > approach makes
> > > the most practical sense from a performance and cost
> > > perspective, given the
> > > technologies that are available today.
> > >
> > >
> > > I hope I have at least provided a few reasons why 4x2.5-Gb/s
> > > WWDM might be
> > > better than a 10 Gb/s serial approach, at least in the
> > > near-term. There is
> > > still a lot to be learned, a lot to be demonstrated, and an
> > > awful lot of
> > > discussion to be had before one solution is chosen over another.
> > >
> > >
> > > -Brian Lemoff
> > > lemoff@xxxxxxxxxx
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > ______________________________ Reply Separator
> > > _________________________________
> > > Subject: Re[2]: 1310nm vs. 1550nm -> Eye Safety + Attenuation
> > > Author: Non-HP-bgregory (bgregory@xxxxxxxxx) at HP-PaloAlto,mimegw2
> > > Date: 5/6/99 9:32 AM
> > >
> > >
> > > In response to Bill's email... regarding the EDFA issue,
> > I'd imagine
> > > that this would only be used in a small number of cases with
> > > a serial
> > > 10GbE approach. I don't think it needs to be a core
> > concern of the
> > > group, but in some dark fiber trunking applications it can
> > > be useful.
> > >
> > > I am most concerned about wavelengths vs. eye safety, and
> > > wavelengths
> > > vs. fiber attenuation. This could end up being a real
> > killer. Four
> > > lasers @ 850nm or 1310nm put out quite a bit of light in an eye
> > > sensitive range. As I remember, four lasers at 1550nm
> offer a lot
> > > more margin. A single source at 1550nm could be very strong
> > > and still
> > > meet the eye safe requirements. This increase in power
> > > combined with
> > > lower fiber attenuation would reduce some of the link distance
> > > problems that we're bound to run into.
> > >
> > > Also, long term I can't see how [4 lasers and an optical
> mux] + [4
> > > photodiodes and an optical de-mux] would be better than a single
> > > source and photodiode. There is a lot of difficult
> > > packaging involved
> > > in the CWDM approach. I think the CWDM solution offers a
> > > quicker path
> > > to market because most of that technology is available
> > > today. But long
> > > term a single 10 Gb source (uncooled DFB without isolator)
> > has a lot
> > > of advantages. It is intrinsically much simpler. I think
> > the board
> > > layout and chip-sets will eventually support this as
> well. If the
> > > standard wanted to be able to scale beyond 10 gigs, even
> > the serial
> > > 10Gb solution could allow further CWDM scaling.
> > >
> > > Regards,
> > > Bryan Gregory
> > > bgregory@xxxxxxxxx
> > > 630/512-8520
> > >
> > >
> > > ______________________________ Reply Separator
> > > _________________________________
> > > Subject: RE: 1310nm vs. 1550nm window for 10GbE
> > > Author: "Bill St. Arnaud" <bill.st.arnaud@xxxxxxxxxx> at INTERNET
> > > Date: 5/6/99 10:38 AM
> > >
> > >
> > > Hmmm. I just assumed that 802.3 HSSG would be looking at 1550
> > > solutions as
> > > well as 1310 and 850
> > >
> > > I agree with you on longer haul links it makes a lot more sense
> > > to operate
> > > at 1550
> > >
> > > I am not a big fan of EFFA pumping. It significantly raises
> > the overall
> > > system cost. It only makes sense in very dense wave long haul systems
> > > typically deployed by carriers.
> > >
> > > CWDM with 10xGbE transcivers should be significantly cheaper. That is
> > > another reason why I think there will be a big market for
> > 10xGbE with all
> > > those transceivers every 30-80km on a CWDM system. However there is a
> > > tradeoff. There is greater probablity of laser failure with many
> > > transceivers and the need for many spares. I figure somewhere
> > > between 4-8
> > > wavelengths on a CWDM and transceivers is the breakpoint where it is
> > > probably more economical to go to DWDM with EDFA. Also EDFA is
> > > protocol and
> > > bit rate transparent.
> > >
> > > An EDFA will ..(edited)..... But EDFA window is very small, so
> > > wavelength
> > > spacing is very tight requiring expensive filters and very stable,
> > > temperature compensated lasers at each repeater site. Also laser
> > > power has
> > > to be carefully maintained within 1 db otherwise you will get
> > > gain tilt in
> > > EDFAs. A loss of a signal laser can throw the whole system off,
> > > that is why
> > > you need SONET protection swicthing. But companies are developing
> > > feedback
> > > techniques to adjust power on remaining lasers to solve this problem.
> > >
> > > A single 10xGbE transceiver will .(edited)....??? Probably less. So 6
> > > 10xGbE transceivers will equal one EDFA. No problems with gain
> > tilt. If
> > > you lose one laser you only lose that channel, not the whole system.
> > > Protection switching not as critical, etc
> > >
> > > Bill
> > >
> > >
> > >
> > > -------------------------------------------
> > > Bill St Arnaud
> > > Director Network Projects
> > > CANARIE
> > > bill.st.arnaud@xxxxxxxxxx
> > > http://tweetie.canarie.ca/~bstarn
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
>
>