RE: [EFM] Active Architectures
Frank
The task force is obviously going to have to make some hard choices about
various cost vs distance vs split ratio tradeoffs sometime soon.
It is not appropriate for us to talk about absolute dollar costs or prices
in the IEEE because that gets us on the edge of anti-competitive
behavior. From the costs I have seen, the cost of CWDM is VERY high
compared to 1310 1000BASE-LX style optics.
I think first we need to agree on a link budget that includes all the
optical choices with distances and various split ratios. Then we need to
agree on various cost multiples for the various solutions, and make the
hard choices accordingly.
We might decide that 10 or 20 km is good enough at reasonable cost, We
might decide on something else. But to date we have not seen
the information or come to enough consensus in the task force to inform
the hard choices,
Bruce Tolley
Cisco Systems
At 03:49 PM 8/21/01 -0400, FEffenberger@QuantumBridge.com wrote:
>Ketan,
>Somewhat, but the cost of CWDM is not that high.
>Also, think twice about that 1310 FP - dispersion is
>going to keep you from using those except at short
>distances. At 1.25 Gb/s and 20km, a DFB is in the cards.
>And, as we've seen from the copper debate, operators
>like long reach.
>
>Frank.
>
>
>
>
>-----Original Message-----
>From: ketan.gadkari@alloptic.com [mailto:ketan.gadkari@alloptic.com]
>Sent: Tuesday, August 21, 2001 2:21 PM
>To: FEffenberger@QuantumBridge.com; hbarrass@cisco.com;
>david.m.horne@intel.com
>Cc: sganguly@yahoo.com; ramu_raskan@angelfire.com;
>stds-802-3-efm@ieee.org
>Subject: RE: [EFM] Active Architectures
>
>
>
>Hi Frank,
>
>I think this approach will be expensive even if you use a CWDM wavelength
>plan. Because each ONU will need a CWDM DFB laser rather than low cost 1310
>Fabry Perot. Also since the CWDM range is only from 1470 to 1610 with a
>20nm channel spacing, only 8 ONUs can be served off a PON.
>
>
>Best Regards,
>Ketan
>
>-----Original Message-----
>From: FEffenberger@QuantumBridge.com
>[mailto:FEffenberger@QuantumBridge.com]
>Sent: Tuesday, August 21, 2001 9:17 AM
>To: hbarrass@cisco.com; david.m.horne@intel.com
>Cc: sganguly@yahoo.com; ramu_raskan@angelfire.com;
>stds-802-3-efm@ieee.org
>Subject: RE: [EFM] Active Architectures
>
>
>
>All,
>We have considered this topology to some degree ourselves.
>The variant we considered is to use TDM in the downstream,
>and WDM in the upstream. The advantages of doing this are
>that you avoid the TDMA protocol issues, and you save N lasers.
>over doing it point-to-point. You also reduce your spectrum
>requirement by a factor of 2 (half as many wavelengths), and
>this can be key if you are using coarse WDM. Since cost is
>key, CWDM would be a good direction. Spectral slicing is
>also an interesting option.
>Versus a TDMA PON, you must add N receivers at the CO; however,
>an array of receivers is *much* more tractable than an array
>of WDM lasers.
>Lastly, the use of WDM in the upstream retains the all passive
>outside plant advantage of PON. No field electronics.
>
>Any interest?
>Frank Effenberger.
>
>
>-----Original Message-----
>From: Hugh Barrass [mailto:hbarrass@cisco.com]
>Sent: Tuesday, August 21, 2001 10:57 AM
>To: Horne, David M
>Cc: 'Sukanta ganguly'; ramu_raskan@angelfire.com;
>stds-802-3-efm@ieee.org
>Subject: Re: [EFM] Active Architectures
>
>
>
>David,
>
>That's a fascinating idea - I like the way you think laterally. A few
>comments:
>
>Firstly, I don't see how this fits into the IEEE 802 model of LAN/MAN
>architecture. The concept of 3+ unidirectional links is pretty scary. Why
>would
>you not go the next step and make it a simple curbside switch with a GE
>uplink
>and copper edge ports?
>
>Secondly, it is not very flexible in topology. An EPON can be configured
>with a
>single 1:16 split point, as a tree with (say) 4 layers of 1:2 / 2:4 / 4:8 /
>8:16
>or even as a broken ring with 16 serial 1:2. It really depends on whose
>right of
>way you are deploying your service into.
>
>Lastly, after thinking about this, it could fit into the definition of EPONs
>as
>they stand. If the upstream (and the downstream if you want) is simply an
>electrical-optical translation then the overall behavior will be the same as
>EPON. I haven't thought deeply about it, but I would guess that a smart
>system
>vendor could make such a device interoperate with standard EPON head ends
>and
>standard EoVDSL CPEs. This could be a great idea - have you patented it?
>
>I think the bottom line is that (according to my first reading) this idea
>doesn't impact the work that we are doing on the 3 media as defined here.
>
>Hugh.
>
>"Horne, David M" wrote:
>
> > On the topic of active architectures, one that seems attractive in
> > comparison to PON for some deployment scenarios could be called a
> > "half-PON." Below I give a proposal for this. Comments appreciated.
> >
> > The half-PON is a hybrid active/passive architecture that preserves the
> > attractive features of PON and P2P while eliminating many of the
> > unattractive features of each.
> >
> > Downstream, it would be the same as the PON downstream (15x0nm GbE from
>PoP
> > to splitter; dedicated fibers from splitter to each of 16 (for example)
> > ONUs).
> >
> > And upstream would be in two pieces:
> >
> > The first would be from the ONUs to the active node (hardened Ethernet
> > switch in node; node also contains the downstream splitter) and has a
> > dedicated fiber per ONU, each to a separate port on the Ethernet switch in
> > the node enclosure (more details in a second).
> >
> > The second part of the upstream would be a single-fiber 13x0nm GbE between
> > the node and the PoP (wavelength-muxed into the same fiber as the
>downstream
> > so only one fiber between node and PoP).
> >
> > ADVANTAGES AND SAVINGS:
> >
> > The key savings come from the use of low power 850nm transmitters between
> > the ONUs and the switch, using 100BaseSX (TIA/EIA 785) as the baseline. So
> > instead of 16 high power (in comparison) 13x0 laser sources (one per ONU)
> > for PON upstream, each capable of >10km reach thru a 16:1 splitter, you'd
> > have 16 low power, low cost 850nm sources (one per ONU) that only have to
> > reach about 300m to the active node, and 1 low power 13x0 (low because no
> > splitter to go thru) source from the switch back up to the PoP. There are
>a
> > couple options on the fiber between the node and the ONU but I'll leave
>that
> > discussion for later.
> >
> > Perhaps more importantly though, in comparison to PON you lose the need
>for
> > developing and agreeing upon a TDMA protocol, a ranging protocol, a sync
> > protocol, and a contention protocol for requests. You also get uniform
> > transmit power back to the PoP since there is only 1 source rather than 16
> > time-multiplexed from different ONUs at different distances, and no
>concerns
> > about run-away transmitter operation bringing down the node. You also get
>a
> > management-capable intermediate network point which will allow greater
> > diagnostic, provisioning, and demarcation capabilities.
> >
> > So, ONUs would be significantly cheaper. On this point there is no
>question.
> > For reference, a 100BaseFX (13x0 laser, 15km reach) to 100BaseTX media
> > converter goes for about 3-4x the cost of a 100BaseSX (850nm, 300m) to
>100TX
> > media converter. Essentially, this is the ONU's function for any of the
> > architectures. Multiply that cost differential by 16 then subtract off a
> > 10km lower power (no splitter to go thru) 1000BaseLX , then add back in
>node
> > powering costs. It seems to be an attractive option as a first order
> > estimate (i.e. thousands of dollars in savings per node branch, serving 16
> > ONUs), and powered nodes are a mature technology with lots of cost
>reduction
> > tradeoffs that can be made.
> >
> > By the way, I am not presenting this as a replacement for PON, but as an
> > alternative that has not been discussed, and may be more attractive in
> > certain situations. It would also be much less development effort since
>all
> > the constituent pieces have a defined Ethernet heritage, which means
>shorter
> > time to market. Arguably it is more future proof than PON since it starts
> > out with 100Mb ports per user, which PON cannot achieve due to TDMA
>overhead
> > and guardbands. It also appears cheaper overall than PON, per user (at
>least
> > in the early going anyway).
> >
> > In any event it is an alternative FTTH architecture that is decoupled from
> > the development time required for PON. The primary development effort
>would
> > involve adding OA&M to 100Base SX (but there are a couple other
>integration
> > decisions to make). The rest of the architecture uses EFM P2P elements as
>I
> > envision it.
> >
> > Any interest?
> >
> > --Dave Horne
> >
> > -----Original Message-----
> > From: Sukanta ganguly [mailto:sganguly@yahoo.com]
> > Sent: Sunday, August 19, 2001 9:06 AM
> > To: ramu_raskan@angelfire.com; stds-802-3-efm@ieee.org
> > Subject: Re: [EFM] EFM Requirements
> >
> > Ramu,
> > A all Fiber architecture will be simpler in the
> > overall aspect but would be a extremely expensive
> > deployment. So wo should have some sort of E/O deliver
> > in the last/first half mile.
> >
> > Rich, Vladimir,
> > An active architecture within the field isn general
> > is not a good idea, but actual scenario may digress
> > from generality. Some switching is required, no doubt.
> > I haven't read any deeper discussion on the switching
> > complexity (Maybe I missed some of the discussions in
> > the past.) I also did not understand the assumption of
> > the last/first 0.5 mile being more scalable than PON.
> > What kind of scalability is required at the last/first
> > mile. If you are talking about 1000baseX being
> > distributed to the real consumer or to then the amount
> > of bandwidth that is to be switched is fairly small
> > (i.e. in comparison to the 10G portion). The switching
> > components as far as scaleability and complexity is
> > concerned will be very different and hence, atleast
> > from my point of view is a very different discussion.
> > I think, and you folks may help me understand it
> > better, it is not a good idea to come up with a
> > generic one switching logic which can be applied to
> > 100base-X/1000base-X and 10G network.
> > I would be extremely interested in discussing the
> > active component network on different scale of
> > operation as opposed to a PON as far as cost/ease of
> > deployment and maintainence, complexity etc is
> > concerned.
> >
> > My two cents.
> >
> > Thanx
> > SG
> > (Sukanta Ganguly, An independent view)
> >
> > --- ramu <ramu_raskan@angelfire.com> wrote:
> > >
> > > Rich, not sure I understand the logic behind some of
> > > your points, but the simple answer appears to be
> > > that it requires new trenching for the new copper
> > > drops, which will never fly. If I misunderstand,
> > > please elaborate.
> > >
> > > I don't quite get you conclusion: 'since E/O is
> > > required, 1KBaseX is significantly more cost
> > > effective, scalable, and simpler than PON.'
> > >
> > > If E/O is required in the field it can't be PON.
> > > Whether it is significantly more cost effective
> > > cannot be judged without detailed designs of each.
> > > Whether it is more scalable I guess depends on your
> > > definition. Simpler is hard to imagine, but again
> > > may depend on definition. If you could elaborate
> > > your view I would be interested.
> > >
> > > Since you are suggesting an active architecture with
> > > new electronics in the field, I for one would
> > > welcome a discussion of such a network architecture
> > > that had fiber for the last thousand feet. No one
> > > has addressed that at all to my recollection. None
> > > of the architectues is perfect in all respects so an
> > > all-fiber active architecture undoubtedly has some
> > > advantages.
> > >
> > >
> > ==================================================================
> > > Vladimir,
> > >
> > > It would seem that the most cost effective approach
> > > for a 10 mile EFM
> > > solution would be to use standard point-to-point
> > > 1000BASE-X or 10GBASE-X
> > > for the first 9.5 miles and then a 0.5 mile copper
> > > tail for the
> > > first/last half mile. Since E/O conversion is
> > > required at the 9.5 mile
> > > mark, standard 1000BASE-X or 10GBASE-X technology
> > > would be significantly
> > > more cost effective, scalable and simpler that PON
> > > at that point. I
> > > expect that there will be switching equipment
> > > located at the upstream
> > > (10 miles away) side, negating any benefit of a PON
> > > split at that point.
> > >
> > > Please tell me what's wrong with this picture?
> > >
> > > P.S. I understand that this does not address the
> > > rural market portrayed
> > > by Frank Miller in this thread, but neither does
> > > PON.
> > >
> > > --
> > >
> > > Best Regards,
> > > Rich
> > >
> > >
> > >
> > > Get 250 color business cards for FREE!
> > > http://businesscards.lycos.com/vp/fastpath/
> > >
> > >
> >
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