In Canada, there is an emerging wholesale ISP model where the regulator (CRTC) forces incumbents to make their last mile available for competitive retail services. This regulatory regime does not YET include FTTH last mile. To this end, I have some questions about FTTH deployments. Any answer to any of the topics is appreciated as it will give me better understanding of some of the technical aspects. *** Wavelengths (ok, this is a newbie question :-) It was my understanding that lasers were on/off devices which transmitted bits very fast. But I suspect I am very wrong on this because this doesnt seem to support RFoG deployment by cable, nor the Verizon FIOS which allocates some spectrum to TV and some to data. Anyone have a good pointer on how the lasers in an FTTH/GPON function ? Are they able to produce a wide range of "colours" and modulate signals ? Or are they really a bitstream with a single narrow colour and it is the hardware at both ends which converts between multi frequency broadcast signals and light pulses ? *** ONT Selection Are there standards similar to DOCSIS where in theory, any ONT *should* work on any GPON system ? (with carriers only qualifying a limited number of models on their system). Or does the selection of the OLT and line cards determine a narrow set of ONTs that are compatible ? Or does it get down to each carrier getting custom made ONTs for the system they are deploying ? Do most ONTs on the market generally allow end user access to some of the config/status data to help in debugging problems ? or are they generally inaccessible by users ? In the case of Bell Canada, I have obtained the following 2 images: http://www.vaxination.ca/temp/ont1.jpg outside equipment http://www.vaxination.ca/temp/ont2.jpg indoors equipment The ONT appears to be the alcatel-lucent equipment indoors. Would this mean that the outdoor equipment really acts only as a demarc which would be just a passive optical connector to join the patch cord to indoors CPE with the optical cable coming from the telephone pole ?
From what I have seen, Verizon FIOS uses an "all-in-1" ONT that is outdoors and provides ethernet, POTS phone and coax for TV services. So each carrier appears to have different approaches. (and Verizon also has spectrum dedicated to TV, spectrum to data and some to voice, which looks like a hybrid RFoG system).
*** IPTV and packet priority/QoS/rate-limit In the case of Bell Canada, they have an IPTV service and they use twin PPPoE sessions on twin VLANs. One is the data connection to/from the BRAS, and the other is the IPTV stream from the Mediaroom data centre. (in the second picture, this would be handled by the black equipment on the left which would be the router that does the PPPoE sessions and outputs ethernet data and MoCA) In their VDSL2 environment, the DSLAM enforces QoS to give IPTV packets priority, reducing data througput to ensure it fits within the limited copper speeds. In an FTTH system, how would this be accomplished ? Would QoS and rate limiting be done by the ONT (since it is the new choke point where subscription speed is imposed), or would the OLT rate limit each end user's total bandwidth and prioritise IPTV packets to ensure it all fits whn it gets to the ONT's rate-limit ? Based on what I heard, those on Bell's FTTH have their IPTV streams fit within their subscription speed, so if they only subscribe to 16mbps service, and use 7mbps for IPTV, they only have 9mbps left for data. *** POTS Service
From a POTS service point of view, is it easy to specify that customer X's SIP traffic goes to server A, while customer Y's traffic goes to server B ? (aka: allow CLECs to provide VoIP service to end users)
From the information I have gathered, Bell uses Corning Flexnap on the telephone poles to connect lines to individual homes. Those are custom made at the factory for each street block (based on distances where each
Does the ONT get the SIP server destination when it is provisioned or does it talk to the OLT and it is the OLT which routes voice traffic to the SIP server assigned to that customer ? **** Installation costs If a carrier has been installing FTTH systems for about 2 years now, would its installation costs have become fairly stable by now, or would they still be going down as the carrier optimises its processes and has more trained crews ? How long does it generally take before they have stable installation costs ? line to home will be). Is this fairly common method ? Or is it considered a more expensive method used by carriers with fewer trained employees ? If a carrier is using Flexnap to save on cable termination/connection manhours, would they also order pre-cut fibre cable runs between the flexnap on the telephone pole and each home ? Or would those be cut and terminated on the field ? And out of curiosity, in a Flexnap setup, what happens if a couple of fibre strands between two poles are damaged by a squirrel ? Does this mean that they have to manually splice the lines from the affected homes into spare strands on the cable ? I appreciate any guidance/information you may provide. The more information I can provide to the regulator, the more informed a debate there can be and thus a better regulatory decision. Jean-François Mezei Vaxination Informatique Montréal, Canada