[Cerowrt-devel] SQM and PPPoE, more questions than answers...

[Dave Taht]

hmm. The pppoe LLC packets are sparse and should already be optimized
by fq_codel, but I guess I'll go look at the construction of those
headers. Perhaps they need to be decoded better in the flow_dissector
code?

I also made some comments re the recent openwrt pull request.

https://github.com/dtaht/ceropackages-3.10/commit/b9e3bafdabb3c5aa47f8f63eae2ecfe34c361855

SQM need not require the advanced qdiscs package, if it checks for
availability of the other qdiscs, and even then nobody's proposed
putting the new nfq_codel stuff into openwrt - as it's still rather
inadaquately tested, and it's my hope that cake simplifies matters
significantly when it's baked. I already have patches for sqm for it,
but it's just not baked enough...

Also I think exploring policing at higher ingres bandwidths is warrented...

On Wed, Oct 15, 2014 at 6:39 AM, Sebastian Moeller <moeller0 at gmx.de> wrote:
> Hi Edwin,
>
>
> On Oct 15, 2014, at 14:02 , Török Edwin <edwin+ml-cerowrt at etorok.net> wrote:
>
>> On 10/15/2014 03:03 AM, Sebastian Moeller wrote:
>>>      I guess it is back to the drawing board to figure out how to speed up the classification… and then revisit the PPPoE question again…
>>
>> FWIW I had to add this to /etc/config/network (done via luci actually):
>> option keepalive '500 30'
>>
>> Otherwise it uses these default values from /etc/ppp/options, and then I hit: https://dev.openwrt.org/ticket/7793:
>> lcp-echo-failure 5
>> lcp-echo-interval 1
>>
>> The symptomps are that if I start a large download after half a minute or so pppd complains that it didn't receive reply to 5 LCP echo packets and disconnects/reconnects.
>
>         I have not yet seen these in the logs, but I will keep my eyes open.
>
>> Sounds like the LCP echo/reply packets should get prioritized, but I don't know if it is my router that is dropping them or my ISP.
>
>         I think that is something we should be able to teach SQM (as long as the shaper is running on the lower ethernet interface and not the pppoe interface).
>
>>
>> When you tested PPPoE did you notice pppd dropping the connection and restarting, cause that would affect the timings for sure…
>
>         Nope, what I see is simply more variance in bandwidth and latency numbers and a less step slope on a right shifted ICMP CDF… I assume that the disconnect reconnects should show up as periods without any data transfer….
>
> Mmmh, I will try to put the PPP service packets into the highest priority class and see whether that changes things, as well as testing your PPP options.
>
> Thanks for your help
>
>         Sebastian
>
>>
>> Best regards,
>> --Edwin
>>
>>
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-- 
Dave Täht

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