Re: [802.3BA] Discussion on 40G for => 10 km SMF
Hi Frank,
I have a couple of brief of comments inline...
> Steve;
>
> I share with your viewpoint, but still have similar concerns,
> so put us in the category of "undecided" regarding this after
> listening to customers from either datacom or telecom side.
>
> The problem is if neither 40g serial or 4x10 CWDM can provide
> a cost trend more favorable than 4x individual 10ge, then
> 40gbe will be hard to take off, everyone may stick to install
I think ~4X the cost of 10G with *just* the benefit of consolidating 4 metro fibers will work quite well.
On top of it add the operational advantage of simplifying the network by reducing the dependency on LAG by a factor of 4 and one could argue that 4X on SMF is perfectly fine.
> 10ge a bit longer, especially for data centers (which is more
> cost sensitive), so 40gbe SMF may eventually unable to build
> up significant volume. Think about the 10gbe volume
> difference regarding LX4 vs. 10ge serial.
Comparing the volumes of optics destined to different applications is not an apple-to-apple comparison. Even though LX4 works on SMF, I believe less than 5% use it for that purpose.
Thanks,
Alessandro
> 4x10g CWDM option may provide a competitive cost point from
> day one, are we underestimating the LX4 mfg issues in terms
> of photonics integrated circuits to drive further cost down?
>
> Are we too optimistic on 40g innovation for cost reduction
> (obviously maybe lengthy and expensive development) keeping
> in mind close to limits of current electronics?
>
> Feel like both 4x10g CWDM and 40ge serial face "breakthrough"
> ahead. Without any reasonable/realistic consensus with these
> "hard" data, seems there would be difficult for the group to
> reach the decision unanimously.
>
> The likely scenarios is if both 40g serial or 4x10 CWDM
> cannot be built more cost-effectively than 4x individual
> 10ge, 40ge SMF will have very limited time window, then
> people will escape it and jump straight to 100GE.
>
> My 1 cent.
> Frank
>
> -----Original Message-----
> From: Trowbridge, Stephen J (Steve)
> [mailto:sjtrowbridge@xxxxxxxxxxxxxxxxxx]
> Sent: Monday, August 04, 2008 8:50 AM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [802.3BA] Discussion on 40G for => 10 km SMF
>
> Hi Mori-san and others,
> It goes without saying that the cost of a 40G 4x10G CWDM
> transceiver will not over the long term fall below 4x the
> cost of a 10G transceiver, but for a very trivial reason: Any
> cost reduction that results from development or volumes of 40
> GbE will also reduce the cost of a quad 10G transceiver. So
> this is a meaningless comparison and not helpful for the
> decision. The decision needs to be made based on how the
> costs of 4x10G CWDM and serial 40G compare to each other, not
> how they compare to the cost of 10G. 40G serial technology
> has been in the market for ~6 years, and is still stubbornly
> expensive. Costs are finally decreasing somewhat, but the gap
> is not being closed vs. 10G because the cost of 10G is
> decreasing even faster than the cost of 40G.
> Regards,
> Steve
>
> -----Original Message-----
> From: Kazuyuki Mori [mailto:mori.kazuyuki-1@xxxxxxxxxxxxxx]
> Sent: Sunday, August 03, 2008 10:21 PM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [802.3BA] Discussion on 40G for => 10 km SMF
>
> TF members,
>
> I'm Kazuyuki Mori, Fujitsu Labs. I support 40G Serial and I
> basically agree with Takai-san regarding below points.
>
> (1) Cost
> My understanding is that, generally speaking, the final
> cost target for 40G optical transceiver should be 2 -3 times
> of 10G transceivers. In order to achieve this target , I
> again and again discussed the cost reduction approaches with
> TOSA/ROSA suppliers, IC suppliers, optical module suppliers
> and our laboratory experts. In case of CWDM, I haven't found
> any technical solution to achieve this target (<x4 cost of
> 10G transceiver), and there has been no presentations in IEEE
> to show this cost reduction approaches until now. On the
> other hand, 40G serial is feasible to achieve this target as
> shown in traverso_02_0708.
> I wonder that 40G transceiver cost will remain more than 4
> times of 10G in future if once CWDM solution is authorized.
>
> (2) Size
> I think the size reduction is another big challenging
> target in CWDM as Chris already agreed in recent dialogues.
> Some people say that monolithic DFB array enables high
> density package solution, but CWDM option is almost
> impossible to be realized because the same active layer of LD
> cannot be applied. Also the hybrid integration using PLC with
> an integrated AWG MUX is sometimes picked up, but it is quite
> challenging due to high insertion loss of AWG caused by
> intrinsic Gaussian profile, and also due to AWG temperature
> dependence. In my perspective as a researcher, optical
> integration approach in 40G CWDM has some intrinsic problems
> and leads the cost increase.
> Please remember that this isn't the case of Vcsel array,
> but the case of DFBs and also with optical mux.
>
> (3) Power
> Steve pointed out that '40G SerDes are very power hungry',
> but this is not correct. Current SerDes is for 16:1 and 1:16,
> however 4:1 and 1:4 SerDes
> should be asuumed in We need to compare using 4:1 and 1:4
> SerDes. In our
> estimation, 2W is possible by deleting unnecessary circuits
> from today's SerDes even when SiGe was used.
>
> Kazuyuki Mori
>
> ----- Original Message -----
> From: "Atsushi Takai" <atsushi.takai@xxxxxxxxxx>
> To: <STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx>
> Sent: Sunday, August 03, 2008 12:34 PM
> Subject: Re: [802.3BA] Discussion on 40G for => 10 km SMF
>
>
> > Jeff
> >
> > I do not know your background.
> > However I found, in your comment below, you misunderstood
> the optical
> > transmission technologies.
> > I do not want to argue line by line.
> >
> > Just I would like to point one sentence:
> > "The biggest downside of 40G serial, seems to be the
> physics problem of
> > PMD.".
> > This is not true for 10km SMF.
> > The 40Gbit/s PMD was a technical challenge in several years
> ago but now it
> > is not downside.
> > Even, we are discussing 1310-nm devices while current
> module includes
> > 1550-nm devices.
> > (We can neglect dispersion issue in case of 1310nm transmission)
> >
> > The biggest cost in current serial module is silicon chip
> that is much
> > more
> > volume sensitive.
> > I hope you know the accumulative shipment of 40Gbt/s client
> module is
> > around
> > 10K peaces or such range.
> > However IEEE confirmed market of 40GbE 10km serial enough for
> > standardization, you can expect much lower cost with higher volume.
> >
> > Also investment for 40Gbit/s transmission networks started
> these years,
> > thus
> > industry started invest for 40Gbit/s technologies.
> > You will find much activity in the industry.
> >
> > All
> >
> > I am very concerning during the meeting and e-mail discussion,
> > many of members may misunderstand the 40Gbit serial
> technology status and
> > activity in the industry,
> > and understand only the surface.
> > We, who has technology especially optical device
> technology, should be
> > responsible to let people understand the technology.
> > I will think about it.
> >
> > =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
> > Atsushi Takai
> > =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
> > ----- Original Message -----
> > From: "Jeff Meyer" <jmeyer@xxxxxxxxx>
> > To: <STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx>
> > Sent: Sunday, August 03, 2008 2:33 AM
> > Subject: Re: [802.3BA] Discussion on 40G for => 10 km SMF
> >
> >
> > Chris has a excellent point about
> >
> > _Other Aspects_
> >
> > It is no longer possible to simply increase Baud to
> match data rate,
> > because of fundamental electrical and optical propagation limits.
> > This was recognized during the 100G SMF PMD discussion,
> with Serial
> > never a viable alternative for the 10km or 40km reach. In the
> > future, all data rates beyond 100G will use some form of
> multi-lane
> > technology. 40G is the inflection point where cost and
> difficulty of
> > Serial rises dramatically compared to multi-lane alternatives.
> > Optical communication has reached the point that all
> other forms of
> > communication (wired or wireless) reached many years ago, where
> > simple modulation format serial solutions are not practical.
> >
> >
> > The biggest downside of 40G serial, seems to be the physics
> problem of
> > PMD. However there are an increasing number of long haul equipment
> > providers who have solved this problem. There have been
> thousands of 40G
> > serial long haul installations deployed to date.
> >
> > As far as the Cost, Power, Size & Reliability I think this favors
> > serial. The cost saving of CWDM seems largely driven by the
> large number
> > of vendors providing 10G IC's and components. But let us
> ponder, if the
> > 10GE fathers chose 4x 2.5G WDM to reduce risk in the late
> 1990's would
> > we be benefiting from the low costs and the large number of
> vendors? All
> > we need is multiple vendors of 40G serial components and
> the prices will
> > plummet. Lets face it the cost of SiGe is not that much
> higher than CMOS
> > unless you get to volumes greater than 100,000 parts. By then, CMOS
> > processes will catch up to SiGe in FT. I am a microwave guy
> and the 40G
> > packaging is not difficult these days ( there are many
> vendors that can
> > do LTCC fine line packages and they are "Open Tooled" so
> you can get a
> > reference design for the 40G electrical packages for no NRE ). If we
> > compare microwave packaging to flip chip mounting of lasers
> and optics,
> > I would imagine optics costs more, but I have no "hard
> data" to support
> > this.
> >
> > The biggest reason why I favor serial over CWDM is the
> leadership for
> > the future. Lets take the risk like the 10G serial
> innovators did in the
> > late 90's. Once we get several manufacturers of 40G parts
> this prices
> > will plummet.
> >
> > Schedule Risk. Albeit the risk for serial is higher but how much?
> >
> > Let's keep technology moving forward for the future generations.
> >
> >
> >
> > Jeff Meyer
> >
> >
> >
> > Chris Cole wrote:
> >
> >> Takai-san痴 7/31/08 email discusses a number of points. Our
> arguments
> >> concerning his first two points (Cost and Time to Market) are
> >> unchanged from cole_04_0708, so are not repeated here. The
> remaining
> >> points are addressed below.
> >>
> >> _Power_
> >>
> >> The long term power consumption of 40GE CWDM and 40GE Serial is
> >> similar. Four 10G un-cooled DFBs and associated Laser Drivers use
> >> about the same power as one cooled 40G EML and associated Modulator
> >> Driver. The remaining ICs are also about the same if
> advanced process
> >> nodes and new designs are assumed. As was pointed out by
> Joel Goergen
> >> during the Q&A session in Denver, a 40GE Serial block diagram has
> >> comparable circuitry to 40GE CWDM block diagram when drawn
> fairly to
> >> permit apples to apples comparison.
> >>
> >> There is no basis for a claim at this late stage in the debate that
> >> Serial has a power advantage over CWDM, and that CWDM
> 菟ower reduction
> >> plans are invisible.・In jewell_03_0508, p.9 and again in
> >> traverso_02_0708 p. 12, ratios of power between an
> aggressive Serial
> >> implementation and CWDM implementation are 0.96 and 0.97,
> i.e. clear
> >> statements in pro-serial presentations that there is no advantage.
> >>
> >> _Size_
> >>
> >> For future generation products, CWDM has an advantage over
> Serial for
> >> fitting into a smaller form factor like QSFP because similar to a
> >> 10GE-LR SFP+, the re-timing CDRs can be moved outside of
> the module.
> >> Serial always has to have the 4:1 SerDes function in the
> module. Even
> >> with aggressive projections about future component size and power,
> >> Serial has a packaging and thermal management design
> challenge to fit
> >> into QSFP.
> >>
> >> What is required to fit 40GE CWDM into QSFP is optics integration.
> >> This type of technology has been described in numerous
> presentations
> >> to the HSSG and involves flip-chipping lasers onto a PLC with an
> >> integrated AWG Mux. The CWDM grid prevents use of a monolithic DFB
> >> array and requires flip-chipping discrete DFBs, but that is a yield
> >> and cost issue not a feasibility or size issue. The time
> line for such
> >> an advanced development program is lengthy, but is similar to
> >> realistic PCB RF-interconnect 40GE Serial development
> schedules. The
> >> investment required to bring this advanced technology to market is
> >> high, again similar to one required for low cost 40GE Serial.
> >>
> >> In contrast, no advanced technology development is
> required to quickly
> >> bring to market first generation low cost CWDM products based on
> >> discrete optics packaged in a larger form factor.
> >>
> >> _Reliability_
> >>
> >> There is no current 1310nm 10G DFB failure data that justifies
> >> bringing up concerns about the reliability of a 4x10G CWDM PMD. 10G
> >> 1310nm PMDs ship in volume today with very high
> reliability. If there
> >> is actual field failure data behind this concern, it would add
> >> credibility to have it presented.
> >>
> >> _Other Aspects_
> >>
> >> It is no longer possible to simply increase Baud to match
> data rate,
> >> because of fundamental electrical and optical propagation
> limits. This
> >> was recognized during the 100G SMF PMD discussion, with
> Serial never a
> >> viable alternative for the 10km or 40km reach. In the
> future, all data
> >> rates beyond 100G will use some form of multi-lane
> technology. 40G is
> >> the inflection point where cost and difficulty of Serial rises
> >> dramatically compared to multi-lane alternatives. Optical
> >> communication has reached the point that all other forms of
> >> communication (wired or wireless) reached many years ago,
> where simple
> >> modulation format serial solutions are not practical.
> >>
> >> Chris
> >>
> >>
> >
>