Re: [Bloat] number of home routers with ingress AQM

[Sebastian Moeller <moeller0@gmx.de>]

Hi Mikael,


> On Apr 2, 2019, at 15:04, Mikael Abrahamsson <swmike@swm.pp.se> wrote:
> 
> On Tue, 2 Apr 2019, Sebastian Moeller wrote:
> 
>> 	See above how Deutsche Telekom deals with that issue, at least in the German market.
> 
> I've read rumours about some ISPs implementing interaction with the VDSL DSLAM where there is an estimation of the current link-speed for each individual customer and then it tries to set the BNG egress shaper appropriately.

	I believe this is what Deutsche Telekom actually does already.

> 
> I am very happy about my FTTH solution I have now since from what I can see the L2 network is almost never a limiting factor (much better than my DOCSIS connection) so my bidirectional SQM with CAKE seems to work very well.

	I envy you ;) that said, I have little issue with my VDSL2 link, but at 50/10 it is hardly pushing the limit. DOCSIS with its often huge segments is a mixed bag, I have head od segments with 1000 customers and no issue even saturating a DOCSIS 3.1 1000/50 plan, and also people with severe issues with more modes 100/20 plans.

> 
> Still, the HGW can never solve these problems properly,

	Assuming fixed bandwidth, it can do a pretty good approximation of properly though ;)

> the egress shaping in the BNG needs to do a proper job.

	I agree, but then my wishlist includes flow-queueing and then reality intervenes, and I keep having to do this on my side as BNGs do not offer fq for customer bandwidth shaping/policing, and might never do.


> From what I have been told, there has been improvements here in the past few years.

	I agree, when I started with Deutsche Telekom latency under saturating load spikes (in ICMP probes) were above 1000ms in 2015, but now with the Juniper BNG shaper solution I saw around 300ms (I switched ISP, but the cap is still around 300ms). IMHO this is much better, but also far away from good enough, so I keep shaping on my end to keep latency acceptable (with a 50/10 link saturating loads are common enough to justify the time spent for configuring the home ingress shaper IMHO).

> 
> What I am more worried about is the egress shaping from the HGW.

	If you ask me that is going to come, all shared media links (docsis, G-PON, ...) already need this to keep customer modems from shouting over each other.

> I talked to several vendors at BBF and they talked about ingress policing being commonly used on the BNG. This means no ingress shaping at all (just packet drops if they exceed the configured rate).

	I wonder how that rhymes with the 300-1000ms added latency I see under load, assuming the BNG-limiter to be the bottleneck.

> I don't know about buffering on the HGW though and how the policed rate is set compared to the L2 rate the HGW can send via.

	Typical DSL modem-routers and DOCSIS modems (presumably < 3.1) often show pretty manly buffering (that is to say probably a bit too much with too little brains attached ;) ). I note that the L4S-project already identified CPEs as the next target to get upstream queueing tackled, I see no chance for doing that effectively without getting the ISPs on board. I have no idea how well the heavy cable labs involvement will sit with the old telco incumbents and whether any non-ITU standard will fly. But let's see...

Best Regards
	Sebastian

> 
> -- 
> Mikael Abrahamsson    email: swmike@swm.pp.se