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What Jorge brought out is MSO’s request that an ONU and a CNU should interoperate with the same OLT port on the same ODN. This actually should be the #1 objective of EPOC. The basic assumption of EPOC is that CNU reuse EPON MAC chip so that the EPOC system has the economic advantage of EPON, preserves the interoperability and provides scalability. It is this goal that bring us together as a SG to prove that it is actually feasible or otherwise. With the understanding that EPOC may not be an optimum solution for coax; we are under certain assumptions or constrains, such as preserving EPON economic by reusing its MAC, let’s get a solid answer to this questing first before diving into other solutions – there are plenty of them. As far as “convertor”, “CMC” and “CLT” are concerned, they were used as convenience to facilities our conversations; instead of call it “that thing” we sometimes call it “convertor”. As time passing by it turn out that the use of “CMU”, “CLT” is actually causing confusions; the “CLT” and “CMC” in many respect are views of the same object from different angles. What this tells us is that we need a good model to describe what we are trying to achieve. Thanks, Eugene From: Edwin Mallette [mailto:edwin.mallette@xxxxxxxxx] Valy, We're talking about two things – products and standards – and I would hate for us to confuse them. The products (assuming all goes well) that could come out of this effort can be varying and myriad. A potential product could be a bridge which terminates the EPON MAC and originates an EPOC MAC. Alternatively, another potential product that could come out of this effort could be something that exists largely below the MAC layer (an Optical Coax Unit / conversion box, if you will.) My goal – whether or not anything like this conversion box or bridge is standardized in 802 – is to ensure such a product is possible. Ed From: Valentin Ossman <Valentin_Ossman@xxxxxxxxxxxxxx> Hi Jorge, I totally understand your concern and tried to raise this in the past meeting in Long Beach. The conversion box in your description is simply called a bridge and is already defined by 802. That bridge has 2 interfaces, EPON for the fiber and an new one for the Coax. The challenge, as you correctly formulated, is to be able to manage and provide the CNUs form the OLT. I completely agree with this statement and want to see this on the EPOC objectives. As a side note, there’ve been discussions about “media converters” or “black magic box” between EPON (fiber) and EPOC (coax). Defining those boxes as PHY layer “media converter” is incorrect in the 802 jargon as it implies that every bit of information from one side is converted to the other side. To be more specific, there is no packet filtering in the media converter as the PHY can’t analyze a data packet (that’s done in the MAC). I propose that we move away from the self-imposed limitation of “media converter” and PHY only protocol and, have a solid discussion on a practical solution that is able to provide a manageable data service between the OLT and the ONU, taking advantage of EPON and the most efficient technologies available for Coax at this time. We should not impose unnecessary technical and physical limitation on the coax just to have a protocol identical to EPON but we must ensure that whatever we define, can work with and be manageable from existent EPON OLT equipment. We must also completely define those “black magic boxes”. There is no point in defining an architecture that relays on an element that is not standardized. I propose we use the well defined functionality of Ethernet switches/bridges for that element. From: Salinger, Jorge [mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx] Paul, David, Howard, and EPoC Study Group members, I'm expanding a discussion that I had with Marek, Ed, and Mark to the entire team. I know this will get unruly, but I see this as a "white elephant in the room" for what seems like some sort of philosophical argument, so might as well get it out in the open. Also, I recognize that this was a subject of discussion during the meeting in Newport Beach, but I did not understand it then and thought it might not be important. I see now that it is a key problem that if not resolved will haunt us forever. So, let's see if we can discuss it via Email and see if we can resolve it before the meeting in Hawaii. My initial statement of the problem to Ed, Mark and Marek, expanded for clarity, is: I struggle with what the CLT is, and what is the problem with the converter that we need to define. I see the EPON and EPoC systems containing these components: EPON: OLT <=== Fiber =====================================> ONUs EPoC: OLT <=== Fiber ====> converter <=== HFC network ====> CNUs The bottom line is that I want to buy a standard OLT, and buy ONUs for customers I can connect via fiber. And, when I can't run fiber to customers, I want to buy a converter between the fiber and the HFC network so I can use the same standard OLT, and use CNUs (an RF version of the ONU) for those customers attached to the HFC network. The FIRST KEY POINT here is that I want to use the same OLT. The SECOND KEY POINT is that I want to buy a passthrough device that will be invisible to the OLT, which will take the optical EPON signals and convert them into RF signals. This passthrough device must be flexible in several ways, such as allowing me to use different portions of the RF spectrum, including more and less spectrum as available. The THIRD KEY POINT is that I want the CNU to be functionally equivalent to the ONU so that the OLT does not know the difference. I think that I want the RF PHY that the converter and the CNU will use to be defined at IEEE because that should make it easier for the vendors that will implement the converter and the CNU to develop it. But people tell me that this will be a problem because, from what I understand, the IEEE does not specify converters or some such rationale. Because of that we have to talk about a CLT instead of the OLT, to hide the converter inside the OLT (if I understood correctly). I hope I was able to keep the definition of the problem simple and clean enough to have a straightforward discussion of why we can't do what I, and my esteemed MSO colleagues, need. So, what is the problem with the converter, and why is there a need to instead define a CLT which is something I don't want to have? Thanks! Jorge <="" p=""> <="" p="">
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