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

[Cameron Ferdinands]

If you'd like. Here's the PDF to the ITU General characteristics for GPON.

http://www.itu.int/rec/T-REC-G.984.1-200803-I/en

No more guessing.

On Wed, Apr 9, 2014 at 3:35 PM, David Beveridge <dave at bevhost.com> wrote:
> On Wed, Apr 9, 2014 at 3:22 PM, Greg Anderson <ganderson at raywhite.com> wrote:
>> On 9 April 2014 12:08, Lincoln Dale <ltd at aristanetworks.com> wrote:
>>> Lincoln Dale | Principal Engineer, Arista Networks Inc. |
>>> ltd at aristanetworks.com
>>> au did: +61 3 9999 7442 | m: +61 417 457 965 | us did: +1 408 547 5782
>>>
>>>
>>> On Mon, Apr 7, 2014 at 8:52 PM, Skeeve Stevens
>>> <skeeve+ausnog at eintellegonetworks.com> wrote:
>>>>
>>>> - The fibre to the home is symmetric capable
>>>
>>>
>>> Not true.  Its not "symmetric capable" because of the timeslots of how the
>>> upstream works.
>>>
>> Not true.  In fact Lincoln, in my understanding you just mistakenly tried to
>> correct Skeeve's statement which was already correct.  I believe the TDM of
>> the NBN's PON network has no bearing on its (a)symmetric nature, only the
>> maximum potential speeds that may be achieved in either direction.
>>
> Must understanding of GPON is as follows. The downstream can transmit in
> any proportion to any endpoint as it sees fit.  The endpoints can only upload
> when they have a time-slot as to avoid a collision with another endpoint.
> If an endpoint is not transmitting any real data, then some of it's timeslice
> can be reallocated to another busier endpoint.
> Therefore there would be some loss of efficiency in upload as the nodes
> adjust the timeslices.  I don't know big of an effect this has in practice.
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