[LibreQoS] [Starlink] Annoyed at 5/1 Mbps...

[Sebastian Moeller]

I have to push back gently on this...

XG(S)-PON is gross 10Gbps (after FEC you are left with around 8,6 Gbps), Noki's proprietary (aka not ITU) @% Gbps PON seems to be abbreviated 25GS-PON.

Now XGS-PON allows maximally 128 end-nodes in the tree, so:
8600/128 = 67.18 Mbps/subscriber

unless the ISPs royally screwed up the configuration there should be a CIR per subscriber of around 60 Mbps. So setting your cake shaper to 50 Mbps shpuld give you:
a) 10 times the throughput of the 5/1 Mbps DSL (ignoring overhead compensation for a change, which likely will be in favor of PON)
b) decent low latency, round robin delay for full MTU packets between 128 active nodes would be: 
	packet/sec: ((8.6 * 1000^3)/(1500*8)) = 716666.666667
	millisec/packet: 1000 / ((8.6 * 1000^3)/(1500*8)) = 0.00139534883721
	round-robin delay 128: 128 * 1000 / ((8.6 * 1000^3)/(1500*8)) = 0.178604651163 milliseconds...

	DSL uses a 4KHz clock so 1000/4000 = 0.25 millisecond quantization
So XGS-PON has at least theoretical potential to deliver lower latency than DSL, but the details depend on if/how packets are aggregated. HOWEVER the 125µsec GPON frames can be shared between different ONUs in upstream and downstream direction... so these are not a hard quantisation but more the interval between control information required for the access grant cycle...

c) robustness against RF noise sources and electricity/lightning

So I am not su sure I would prefer the 5/1 (A)DSL over a PON... 

That however is orthogonal to me preferring a competent ISP that takes care of keeping latency under load at bay.



> On Mar 21, 2023, at 12:26, Rich Brown via Starlink <starlink at lists.bufferbloat.net> wrote:
> 
> 
> 
>> On Mar 21, 2023, at 1:21 AM, Frantisek Borsik via Rpm <rpm at lists.bufferbloat.net> wrote:
>> 
>> Now, I hope to really piss You off with the following statement  :-P but:
>> 
>> even sub 5/1 Mbps “broadband” in Africa with bufferbloat fixed on as many hops along the internet journey from a data center to the customers mobile device (or with just LibreQoS middle box in the ISP’s network) is feeling way better than 25Gbps XG-PON. The only time the XG-PON guy could really feel like a king of the world would be during his speedtest.
> 
> Nope. Sorry - this doesn't piss me off :-) It's just true. 
> 
> - 7mbps/768kbps DSL with an IQrouter works fine for two simultaneous Zoom conferences. (Even though no one would think that it's fast.)
> - I recommend people on a budget drop their ISP speed so they can afford a router that does SQM https://forum.openwrt.org/t/so-you-have-500mbps-1gbps-fiber-and-need-a-router-read-this-first/90305/40

	Even simpler, even on a 100Gbps link nobody stops you from setting your shaper to 50/10 if that is all your router can deliver (and I agree if there are cheaper plans closer to the 50/10 it makes economic sense to scale down the plan)...


> 
> The people that get annoyed are those who just upgraded to 1Gbps service and still are getting fragged in their games.
> 
> Rich
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