Re: Grand Apagon - Electricity (not) in Spain

On 2025-05-06 12:26, Carlos E.R. wrote:

On 2025-05-06 11:25, Martin Brown wrote:
 

Amazingly fibre to premises can still work OK in a power cut since that is actually powered off the reserve supply back at the main exchange.
Advantages of having a UPS at home.

 Here there are boxes on the walls of the city blocks, where one fibre from the exchange is divided into half a dozen (exact number unknown to me). I don't know if these boxes are passive or active.
 <https://www.google.com/imgres? q=cajas%20de%20reparto%20de%20fibra%20telefonica&imgurl=https%3A%2F%2Fcomunidad.movistar.es%2Ft5%2Fimage%2Fserverpage%2Fimage-id%2F111764iC1F6FAD7948695D6%3Fv%3Dv2&imgrefurl=https%3A%2F%2Fcomunidad.movistar.es%2Ft5%2FSoporte-Fibra-y-ADSL%2FINSTALACION-CAJA-DISTRIBUIDORA-DE-FIBRA-EN-EXTERIOR-DEL-EDIFICIO%2Ftd-p%2F2929655&docid=zZHuHCpt8An46M&tbnid=0T2mKKO1TLeZFM&vet=12ahUKEwiN9onmz46NAxXYVqQEHYnHDk4QM3oECHMQAA..i&w=914&h=611&hcb=2&ved=2ahUKEwiN9onmz46NAxXYVqQEHYnHDk4QM3oECHMQAA>
 <https://www.change.org/p/movistar-cambien-cto-caja-donde-se-conecta-la- fibra-optica-para-poder-realizar-mis-estudios>
  I could not test if my landline phone worked during the outage because my local UPS went down too soon.
 

I found another link that explains the system. Not sure if this is what everybody here has, but I think yes.
<https://bandaancha.eu/articulos/puede-fibra-realmente-dar-1gb-simetrico-9834>
GPON
                                                          16 fibres
[exchange]-------[splitter]-----------------[CTO 1:16]---/-------> home
                     1:4     \---
                              \---
                               \---
Results in 2.488,32 Mbps divided between 64 clients. So, if the other clients are not busy, you get the gigabit stream.
«With this architecture, the laser light coming from the OLT located in the central unit simultaneously illuminates the 64 ONTs, passing through the two levels of division mentioned above. In order for each ONT to receive its information, the GPON standard divides each second into 8,000 fragments of 125 microseconds, which are dynamically assigned to each ONT depending on the throughput requested and available. All of them will receive the signal, but they will only be able to read the information that corresponds to them, since the information of the other users is encrypted.
Translated with DeepL.com (free version)»
It is time multiplexing again, not routing. This way the splitter can be optical, no electronics needed — this is my guess, the article doesn't say.
<https://en.wikipedia.org/wiki/GPON>
<https://es.wikipedia.org/wiki/GPON>
The Spanish Wikipedia has a different content, and says this:
«Downstream - Broadcast
All data is transmitted to all ONTs (the splitter is a passive element that simply replicates the input data to all outputs). Each ONT filters the received data (it only keeps the data that is directed to it). It has the problem that the operator/user may want confidentiality of the data, which is solved by encrypting the data.
Upstream - TDMA
Conceptually similar technology to TDMA (Time Division Multiple Access) is used. The OLT controls the upstream channel, allocating time windows to the ONTs. Medium access control is required to avoid collisions and to distribute bandwidth among users.
As the optical splitter is a passive element, perfect synchronisation of the incoming upstream packets is necessary for it to be able to form the GPON frame. It is therefore necessary for the OLT to know the distance between the ONTs to take the delay into account.
Translated with DeepL.com (free version)»
The other article says that upstream with Movistar each client has actually 19,44 Mb
--
Cheers, Carlos.