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Re: [EFM] Wavelength allocation

In the interest of taxonomy clarity we need a terminology that 
differentiates between actual PTP (via the physics of materials) and 
virtual PTP (via the physics of frequency spectra).   Maybe MPTP and FPTP.

Also in the interest of taxonomy clarity we probably also need a 
terminology that differentiates between fixed and variable frequency 
assignments (since everything happens at a band of the electromagnetic 
spectrum), maybe fixed frequency (wavelength) vs frequency (wavelength) 
agile solutions.

Whether frequency agility is undertaken as an element of TDMA EPON is a 
decision that needs to be made at some point, though is obviously 
influenced by the current relative cost of frequency (wavelength) agility.


At 08:20 AM 7/17/01 -0300, Carlos Ribeiro wrote:

>I've tried to send this message a few times over the weekend, but I didn't 
>get through. I'm trying again, because this is a very important topic, 
>looking from the carrier's perspective.
>Most EPON proposals are P2MP. You have to use a sophisticated arbitration 
>mechanism to control the use of the upstream channel. Although complex and 
>initially expensive, DOCSIS did this before, and with high volume the cost 
>of CPEs is driven down. However, the user is still concerned with the 
>security (ok, we know it's almost impossible to tap the neighboor upstream 
>signal, but go figure customer's mind :-). Also, the amount of bandwidth 
>is limited by design. Any changes must be implemented by all elements in 
>the give cable/fiber segment.
>In the P2P EPON proposal, each customer gets their own wavelength. You 
>have PON at the physical level, but a point-to-point connection at the 
>upper layers. I believe this is the best of both worlds, because you have 
>high speed, and you can provide dfferentiated services for some customers 
>in the segment. You're not stuck with the technology of the traditional 
>PON central node.
>As the technology evolves, it's possible that we'll hit the technical 
>limitations of the first generation EPON systems - the ones that are going 
>to be deployed in the next months. In the cable industry, you use smaler 
>segments to improve efficiency. Using P2MP EPON, you can do the same, but 
>you can also start to deploy new wavelengths for the new services. In 
>fact, it is possible to envision a scenario where you end up allocating a 
>wavelength for every individual customer, turning your P2MP network into a 
>P2P network.
>Other applications can (and should) user their own wavelengths. The best 
>example that comes to mind is broadcast video - it's much more efficient 
>and less expensive to deliver it using a separate lamda, than trying to 
>carry it over packets.
>As it is, I would like the EFM standard to include a wavelength allocation 
>policy. I haven't seen this discussed in depth; some presentations touch 
>on this topic slightly. There is someone working specifically on this?
>Carlos Ribeiro
>CTBC Telecom