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Re: [EFM] Active Architectures


> Any interest?

Yes, considerable. Thank you for presenting those views. 


"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)

FWIW, a question (and a hint;) :

For extremely long runs, have you considered the tradeoffs of an inexpensive cwdm 
solution in lieu of multiple strands coming back from the ONUs?


> 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).
> 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@xxxxxxxxx]
> Sent: Sunday, August 19, 2001 9:06 AM
> To:;
> 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@xxxxxxxxxxxxx> 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!
> >
> > 
> > 
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