[AusNOG] Why not Symmetric ingress and egress?

Tim McCullagh technical at halenet.com.au
Thu Jun 17 11:22:29 EST 2010


----- Original Message ----- 
  From: John Lindsay 
  To: ausnog at ausnog.net 
  Sent: Thursday, June 17, 2010 9:59 AM
  Subject: Re: [AusNOG] Why not Symmetric ingress and egress?


  There are also some limits in the FTTH network architecture that mean there is less total bandwidth in the back channel.

  Not necessarily,  that may be true for GPON which is what NBN is going to use, but GEPON equipment has no such limitation.   Even for GPON it can hardly be used as an excuse to have a 25 down 5 MB up etc.  Unfortunately with NBN we will be locked into GPON.  


  It is easy to prioritise the traffic from one head end to hundreds of end users.  It is much harder to control those end points when they each want to transmit over one shared path.  

  Not all vendors would be affected by this, as I understand it prioritorisation is done in the management system profiles and once setup can be duplicated across multiple head ends, between head ends is a matter of having sufficient switching / routing and backhaul.  Most backhaul is synchronous, so I am not sure why that should be an issue.  

  For mine it comes down to protecting the business customer revenue as much as anything.  

  Some of the issues has come down to the choice of equipment vendors.   As always in choosing a vendor big is not always better.   

  Much of the equipment deployed (presently) in Australia is not the same vendor as NBNs choice. Other than Telstra, most deploy Wave7 / Enablence kit in either GPON or GEPON or both varieties.  Then there is some hills equipment.  Personally I don't see why a GPON solution was chosen over a GEPON solution other than that the GPON vendor was familiar to the powers to be at NBN.   In fact I think it was a dumb choice, but that is just my 2 bobs worth.  This is all really back to the future stuff.  I wonder how long it will take to hear the cries from the public re lack of competition and choice re NBN, in the same way as happened in the 1970s.   

  It strikes me that there are too many so called experts that have never done any FTTH deployments that simply do not understand the issues.  Fibre is sexy so we should do it stuff, when fibre should be driven by a business case.  

  I really do pity the 55% of homes that are going to get aerial FTTH, talk about recipe for disaster.  It isn't the same as copper, you can't just scotch lock a bit into it when it gets brought down by wind, fires trucks etc.   For those that want to remind me about backhoe fade, yes that happens in one spot.   In the case of fire and wind it will happen in many spots, over large geographic areas.  Trying to reconstruct quickly will take time.  You cant run fibre acress a driveway to effect quick repairs like copper.  I could go on but I am already off topic.

  regards Tim
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ausnog.net/pipermail/ausnog/attachments/20100617/bcab20a5/attachment.html>


More information about the AusNOG mailing list