[AusNOG] Discussion point: Why aren't the NBNCo tails symmetric in speed?

[Tony]

On Thu, 10 Apr 2014 01:18:19 +1000, Paul Brooks  
<pbrooks-ausnog at layer10.com.au> wrote:

>
> Why it is 100/40 at the top speed and not 100/50 is harder to answer.


Two "maybe" answers I can think of:

1. Perhaps they are allowing for a certain number of symmetrical services.  
If the PON split is 24, then (20 * 40) + (4 * 100) = 1200 (upstream),  
which would mean they could have 20 x 100/40 & 4 x 100/100 on each  
2.4/1.2G of bandwidth ?

2. To allow sufficient breathing space for the TC-1 traffic, which I  
believe is in addition to the 100/40 (it's only 150kbps each service).  
Given that voice is real time and delay sensitive it might need to be  
guaranteed certain timeslot allocation in the upstream direction that  
reduce the overall bandwidth available.

Both are pure speculation on my part :)


regards,
Tony.