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RE: [EFM] Active Architectures


I think the architecture you describe merits further

With the exception of downstream 
broadcast delivery, the architecture is similar to 
what Gerry Pesavento referred to as "curb-switched
ethernet" in one of his EFM presentations (May, 2001).
Downstream PON-like delivery adds some complexity
relative to straight-forward ethernet switching, 
but the payoff is one customer could get the full 
downstream bit rate if no other customers are using
the network.  1 Gbps downstream, 100 Mbps upstream 
sounds pretty good!

One big issue I see with your proposal is the
need for security, which obviously also exists in the
regular PON scenario.  This can certainly be solved.


-----Original Message-----
From: Horne, David M [mailto:david.m.horne@xxxxxxxxx]
Sent: Monday, August 20, 2001 9:58 PM
To: ''
Subject: FW: [EFM] Active Architectures

No problem, a figure would probably have been easier to see it all, but even
a figure ends up being pretty busy. Still, I figured that:


would have gotten a tad more interest. 

-----Original Message-----
From: Frank Coluccio [mailto:fcoluccio@xxxxxxxxxxxxxxxxx]
Sent: Monday, August 20, 2001 4:24 PM
To: fcoluccio@xxxxxxxxxxxxxxxxx
Cc: david.m.horne@xxxxxxxxx; sganguly@xxxxxxxxx;
ramu_raskan@xxxxxxxxxxxxx; stds-802-3-efm@i
Subject: Re: Re: [EFM] Active Architectures

Dave, All, 

Kindly disregard my earlier question concerning cwdm. I mistook the section
question, thinking instead that it was between the head end/OLT and a field 
cluster. Apolgoies to all.


> Dave,
> > Any interest?
> Yes, considerable. Thank you for presenting those views. 
> Re:
> "Downstream, it would be the same as the PON downstream (15x0nm GbE from
> to splitter; dedicated fibers from splitter to each of 16 (for example)
> ONUs)." 
> FWIW, a question (and a hint;) :
> For extremely long runs, have you considered the tradeoffs of an
> 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
> > 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
> > the node enclosure (more details in a second).
> > 
> > The second part of the upstream would be a single-fiber 13x0nm GbE
> > the node and the PoP (wavelength-muxed into the same fiber as the
> > so only one fiber between node and PoP).
> > 
> > 
> > The key savings come from the use of low power 850nm transmitters
> > the ONUs and the switch, using 100BaseSX (TIA/EIA 785) as the baseline.
> > instead of 16 high power (in comparison) 13x0 laser sources (one per
> > for PON upstream, each capable of >10km reach thru a 16:1 splitter,
> > have 16 low power, low cost 850nm sources (one per ONU) that only have
> > reach about 300m to the active node, and 1 low power 13x0 (low because
> > 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
> > discussion for later.
> > 
> > Perhaps more importantly though, in comparison to PON you lose the need
> > 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
> > time-multiplexed from different ONUs at different distances, and no
> > 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
> > 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
> > 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
> > 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
> > ONUs), and powered nodes are a mature technology with lots of cost
> > 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
> > the constituent pieces have a defined Ethernet heritage, which means
> > time to market. Arguably it is more future proof than PON since it
> > out with 100Mb ports per user, which PON cannot achieve due to TDMA
> > and guardbands. It also appears cheaper overall than PON, per user (at
> > in the early going anyway).  
> > 
> > In any event it is an alternative FTTH architecture that is decoupled
> > the development time required for PON. The primary development effort
> > involve adding OA&M to 100Base SX (but there are a couple other
> > decisions to make). The rest of the architecture uses EFM P2P elements
as I
> > envision it. 
> > 
> > Any interest?
> > 
> > --Dave Horne