RE: WWDM vs. 10Gb/s serial
- To: "bill.st.arnaud" <bill.st.arnaud@xxxxxxxxxx>, Nader Vijeh <nader@xxxxxxxxxxxxxx>, stds-802-3-hssg <stds-802-3-hssg@xxxxxxxx>
- Subject: RE: WWDM vs. 10Gb/s serial
- From: pbottorf@xxxxxxxxxxxxxxxxxx (Paul Bottorff)
- Date: Mon, 10 May 1999 10:44:33 -0700
- Sender: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
Bill:
I certainly agree that the PHY must provide fast failure detection (<10
msec). In addition, it would be nice if the PHY layer could inform the
transmitting end of failures.
10 GigE has a broad range of uses for both LAN and WAN applications. The
design tradeoffs for photonics in the WAN and LAN are different. In the WAN
a major component of cost is the optical reach. The data which I've seen
indicates that transmission frequency very significantly affects reach. To
get the lowest cost solutions 10 GigE should move away form group codes
systems like 8/10 into scrambler code systems. Scrambling provides an NRZ
efficient line encode giving 10 gigabits of data at 10 gigabaud.
Paul
Paul A. Bottorff
Director Switching Architecture, Bay Architecture Lab
Nortel Networks, Inc
pbottorf@xxxxxxxxxxxxxxxxxx
At 09:04 AM 5/10/99 -0400, Bill St. Arnaud wrote:
>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
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> >
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