GPON Technology

Routing & Switching Network Management
1

Hello, everyone.

I’m not sure if this is the right place to ask so let me know if it isn’t!

I work at an ISP space and I encountered a technology called GPON. I understand that the principle is the following:

  1. The router installed at the customers’ premises is called the ONT
  2. The device inside the ISP’s space which connects the infrastructure is called the OLT
  3. The principle works in a way where a point-to-multipoint topology is built. If a customer watches YouTube or something, it will send the packets through the GPON network to the OLT.
  4. Once the OLT replies, a splitter splits this signal and sends it to every ONT connected to the GPON network (and they use some form of identification to determine whether the traffic is for them)

GPON_topology
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My question is about the 4th point. Are responses from the OLT the only thing that is split to all customers? To clarify this point a bit more, this is the traffic flow form the OLT to the ONTs.

obrázok
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If one of the ONTs opens up YouTube, is the traffic also split or only sent to the OLT?

And one final question, if the OLT really does send something to all customers, what if there is a customer that is, say downloading a big file? Wouldn’t this saturate the links of the other customers, considering that everything is broadcasted there?

Thank you
David