Last Mile Design

Miles Fidelman mfidelman at
Sat Feb 9 20:23:29 UTC 2019

On 2/9/19 2:51 PM, Grant Taylor via NANOG wrote:

> On 2/9/19 12:12 PM, Miles Fidelman wrote:
>> With early PON designs, upstream bandwidth was horrible. Not 
>> particularly useful if you're doing things like remote backup, or 
>> video chatting, or running a server (business grade service). GPON 
>> does better on upstream bandwidth, but it's still asymmetric.
> Intriguing.
> I would have not considered my municipal GPON to be asymmetric. Well, 
> not as such.  Routinely, when I do speed tests I get better upstream 
> speeds than I do downstream speeds.  (More below.)
>> If you're marketing to business customers, or home office 
>> professionals, of families with multiple users that consume upstream 
>> bandwidth, AE gives you a lot of room for upside growth (assuming you 
>> provision the right kinds of fiber).
> Are you referring to the dedicated bandwidth between the CPU and the 
> AE equipment?  Or the fact that bandwidth feeding the GPON and all 
> subscribers is aggregate?

I'm thinking about the backside.  Generally there's a lot more 
downstream bandwidth to distribute, and not a lot of upstream 
bandwidth.  Makes a lot of sense if you're a content provider & expect 
your customers to be passive consumers (also, considering that a lot of 
that bandwidth might be used for things other than IP packets).

> I have attributed the asymmetry in my speed tests to be that most 
> people on my GPON are predominantly downloading, thus consuming 
> aggregate download bandwidth.  Conversely, few are uploading more than 
> requests, thus using relatively little of the aggregate upload bandwidth.

Probably the case.  But if you're in an area with a lot of home office 
users, or gamers, or business grade customers running servers, your 
experience might be different.

> Do I see asymmetry?  Yes.  Is it truly asymmetric?  I don't think so.  
> I think is just based on consumption of aggregate bandwidth.
> I have no idea if this is normal for GPON or not.  Hence one of the 
> reasons that I'm finding this thread enlightening.
The SPECS are asymmetric, as is the technology when you take into 
account allocation of bandwidth between downstream video & IP services.


In theory, there is no difference between theory and practice.
In practice, there is.  .... Yogi Berra

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