Re: Problem to priorize SSH traffic

[Alan Goodman <notifications@xxxxxxxxxxxxxxxxxxxxxxxx>]

In my experience those types of graphs dont take into account overhead.  
Therefore bandwidth used may look smaller than it is in reality.  If you 
look at tc -s qdisc show interfacename youll see what the rate estimator 
thinks the rate is which ought to be more accurate.

I usually set ceiling rate at 95-99% of your upload sync speed, 
depending upon how many errors the line has on upstream.

The simplified explanation for why the bandwidth graphs can be lower 
than expected is they dont take into account the ATM overheads.

The slightly more in depth explanation would be overhead estimation is 
important on ATM type connections because the cells transmitted on the 
wire have to be a certain size, if the data packet is smaller than this 
certain size then the atm cell is padded to make it up to the minimum 
size.  If you dont account for this then your rate estimation can be 
very inaccurate.

I would run the ATM overhead detector first to ensure that you are not 
over stating that overhead value.  The output from the matlab script 
will give you the stab parameters that are approximately correct for 
your connection.  I find those to be a good starting point in general.

Alan


On 17/12/16 12:27, Ludovic Leroy wrote:
> Alan,
>
> You are right. This solution gives immediate relief.
> I cannot believe tuning the overheads has such an impact on upload 
> rates. That is the way it is...
> But you can see in the attached picture that the upload bandwidth 
> drops down to 700kbit from 800kbit.
> Do you have an idea how to return to the sync speed?
> Thank you once again.
>
> Ludovic
>
> Le 17/12/2016 11:23, Alan Goodman a écrit :
> > Hi,
> >
> > The obvious issue at present is that your upload rate isnt hitting 
> > the ceiling rate you have specified, or at least the rate estimator 
> > doesnt think it is.  This could be because you've set your upload 
> > incorrectly (what is your sync speed) or could be because you are not 
> > accounting for the overheads and ATM characteristics in your 
> > connection (makes the rate estimator inaccurate).
> >
> > You should try adding stab overhead 40 linklayer atm to your root qdisc.
> >
> > The overhead 40 bit will be whatever number 
> > https://github.com/moeller0/ATM_overhead_detector figures out for 
> > you.  If you dont have matlab you can send me your ping collection 
> > result (bzip it first and send it off list or upload it some place 
> > please) and I will process it for you.
> >
> > Alan
> >
> >
> > On 16/12/16 21:16, Ludovic Leroy wrote:
> > > Thanks for replying.
> > > The script is attached. Hope this helps.
> > >
> > > Ludovic
> > >
> > > Le 16/12/2016 21:34, Alan Goodman a écrit :
> > > > It might help if you provide the script you are using to build your 
> > > > tc queues...  I find this more readable than the output from the tc 
> > > > stats.
> > > >
> > > > Alan
> > > >
> > > >
> > > > On 16/12/16 16:50, Ludovic Leroy wrote:
> > > > > Hello LARTC community,
> > > > >
> > > > > I am building a TC policy at home that answers my needs for a 
> > > > > small DSL uplink 800kbit:
> > > > > * High UDP responsiveness for DNS queries and ping (Leaf 1:10 prio 1)
> > > > > * SSH traffic gets higher priority. I view my camera remotely via 
> > > > > ssh tunnel (Leaf 1:20 prio 2)
> > > > > * Guarantied http(s)/IMAP (Leaf 1:30 prio 3)
> > > > > * Torrent seeding (Leaf 1:40 prio 4)
> > > > > * Default (Leaf 1:99 prio 5)
> > > > > * Gigabit local network (Leaf 1:1000 prio 1000)
> > > > >
> > > > > The problem is torrent traffic consumes all the bandwidth leaving 
> > > > > little room for SSH traffic (<100kbit). See attached picture.
> > > > > SSH traffic class with higher priority than torrent class should 
> > > > > be offered excess bandwidth first, but that is not the case.
> > > > > The only solution I found is to reduce the torrent ceil value.
> > > > > Could you help me?
> > > > >
> > > > > Regards,
> > > > >    Ludovic L.
> > > > >
> > > > > # tc -d class show dev eth1
> > > > > class htb 1:99 parent 1:1 leaf 199: prio 5 quantum 1650 rate 
> > > > > 66Kbit ceil 800Kbit linklayer ethernet burst 16Kb/1 mpu 0b 
> > > > > overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 0
> > > > > class htb 1:10 parent 1:1 leaf 110: prio 1 quantum 1650 rate 
> > > > > 66Kbit ceil 200Kbit linklayer ethernet burst 16Kb/1 mpu 0b 
> > > > > overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 0
> > > > > class htb 1:1000 root prio 0 quantum 200000 rate 100Mbit ceil 
> > > > > 100Mbit linklayer ethernet burst 1600b/1 mpu 0b overhead 0b cburst 
> > > > > 1600b/1 mpu 0b overhead 0b level 0
> > > > > class htb 1:1 root rate 800Kbit ceil 800Kbit linklayer ethernet 
> > > > > burst 16Kb/1 mpu 0b overhead 0b cburst 1599b/1 mpu 0b overhead 0b 
> > > > > level 7
> > > > > class htb 1:20 parent 1:1 leaf 120: prio 2 quantum 9900 rate 
> > > > > 396Kbit ceil 800Kbit linklayer ethernet burst 16Kb/1 mpu 0b 
> > > > > overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 0
> > > > > class htb 1:30 parent 1:1 leaf 130: prio 3 quantum 4950 rate 
> > > > > 198Kbit ceil 800Kbit linklayer ethernet burst 16Kb/1 mpu 0b 
> > > > > overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 0
> > > > > class htb 1:40 parent 1:1 leaf 140: prio 4 quantum 1650 rate 
> > > > > 66Kbit ceil 800Kbit linklayer ethernet burst 16Kb/1 mpu 0b 
> > > > > overhead 0b cburst 1599b/1 mpu 0b overhead 0b level 0
> > > > > class sfq 140:22 parent 140:
> > > > > class sfq 140:34 parent 140:
> > > > > class sfq 140:3b parent 140:
> > > > > class sfq 140:6c parent 140:
> > > > > class sfq 140:a9 parent 140:
> > > > > class sfq 140:149 parent 140:
> > > > > class sfq 140:287 parent 140:
> > > > > class sfq 140:2fd parent 140:
> > > > > class sfq 140:318 parent 140:
> > > > > class sfq 140:376 parent 140:
> > > > > class sfq 140:3d6 parent 140:
> > > > > class sfq 140:3e3 parent 140:
> > > > >
> > > > > # tc -d qdisc show dev eth1
> > > > > qdisc htb 1: root refcnt 2 r2q 5 default 99 direct_packets_stat 2 
> > > > > ver 3.17 direct_qlen 1000
> > > > > qdisc pfifo 110: parent 1:10 limit 1000p
> > > > > qdisc pfifo 120: parent 1:20 limit 1000p
> > > > > qdisc pfifo 130: parent 1:30 limit 1000p
> > > > > qdisc sfq 140: parent 1:40 limit 127p quantum 1514b depth 127 
> > > > > flows 128/1024 divisor 1024 perturb 10sec
> > > > > qdisc sfq 199: parent 1:99 limit 127p quantum 1514b depth 127 
> > > > > flows 128/1024 divisor 1024 perturb 10sec
> > > > >
> > > > > # tc -d filter show dev eth1
> > > > > filter parent 1: protocol all pref 1 fw
> > > > > filter parent 1: protocol all pref 1 fw handle 0xa classid 1:10
> > > > > filter parent 1: protocol all pref 2 fw
> > > > > filter parent 1: protocol all pref 2 fw handle 0x14 classid 1:20
> > > > > filter parent 1: protocol all pref 3 fw
> > > > > filter parent 1: protocol all pref 3 fw handle 0x1e classid 1:30
> > > > > filter parent 1: protocol all pref 4 fw
> > > > > filter parent 1: protocol all pref 4 fw handle 0x28 classid 1:40
> > > > > filter parent 1: protocol all pref 99 fw
> > > > > filter parent 1: protocol all pref 99 fw handle 0x63 classid 1:99
> > > > > filter parent 1: protocol all pref 1000 fw
> > > > > filter parent 1: protocol all pref 1000 fw handle 0x3e8 classid 
> > > > > 1:1000
> > > > >
> > > > > # tc -s class show dev eth1
> > > > > class htb 1:99 parent 1:1 leaf 199: prio 5 rate 66Kbit ceil 
> > > > > 800Kbit burst 16Kb cburst 1599b
> > > > >   Sent 1705141 bytes 10742 pkt (dropped 0, overlimits 0 requeues 0)
> > > > >   rate 8048bit 6pps backlog 0b 0p requeues 0
> > > > >   lended: 10742 borrowed: 0 giants: 0
> > > > >   tokens: 29290142 ctokens: 198864
> > > > >
> > > > > class htb 1:10 parent 1:1 leaf 110: prio 1 rate 66Kbit ceil 
> > > > > 200Kbit burst 16Kb cburst 1599b
> > > > >   Sent 20229 bytes 229 pkt (dropped 0, overlimits 0 requeues 0)
> > > > >   rate 48bit 0pps backlog 0b 0p requeues 0
> > > > >   lended: 229 borrowed: 0 giants: 0
> > > > >   tokens: 30859841 ctokens: 943734
> > > > >
> > > > > class htb 1:1000 root prio 0 rate 100Mbit ceil 100Mbit burst 1600b 
> > > > > cburst 1600b
> > > > >   Sent 79426 bytes 563 pkt (dropped 0, overlimits 0 requeues 0)
> > > > >   rate 784bit 1pps backlog 0b 0p requeues 0
> > > > >   lended: 563 borrowed: 0 giants: 0
> > > > >   tokens: 1917 ctokens: 1917
> > > > >
> > > > > class htb 1:1 root rate 800Kbit ceil 800Kbit burst 16Kb cburst 1599b
> > > > >   Sent 164307843 bytes 134601 pkt (dropped 0, overlimits 0 
> > > > > requeues 0)
> > > > >   rate 796440bit 78pps backlog 0b 0p requeues 0
> > > > >   lended: 108779 borrowed: 0 giants: 0
> > > > >   tokens: 2192729 ctokens: -117287
> > > > >
> > > > > class htb 1:20 parent 1:1 leaf 120: prio 2 rate 396Kbit ceil 
> > > > > 800Kbit burst 16Kb cburst 1599b
> > > > >   Sent 5042698 bytes 4448 pkt (dropped 0, overlimits 0 requeues 0)
> > > > >   rate 64032bit 6pps backlog 0b 0p requeues 0
> > > > >   lended: 4448 borrowed: 0 giants: 0
> > > > >   tokens: 5142031 ctokens: 235296
> > > > >
> > > > > class htb 1:30 parent 1:1 leaf 130: prio 3 rate 198Kbit ceil 
> > > > > 800Kbit burst 16Kb cburst 1599b
> > > > >   Sent 32111 bytes 216 pkt (dropped 0, overlimits 0 requeues 0)
> > > > >   rate 0bit 0pps backlog 0b 0p requeues 0
> > > > >   lended: 216 borrowed: 0 giants: 0
> > > > >   tokens: 10309330 ctokens: 241546
> > > > >
> > > > > class htb 1:40 parent 1:1 leaf 140: prio 4 rate 66Kbit ceil 
> > > > > 800Kbit burst 16Kb cburst 1599b
> > > > >   Sent 157507664 bytes 118966 pkt (dropped 0, overlimits 0 
> > > > > requeues 0)
> > > > >   rate 724312bit 65pps backlog 0b 27p requeues 0
> > > > >   lended: 10187 borrowed: 108779 giants: 0
> > > > >   tokens: -2031932 ctokens: -222767
> > > > >
> > > > > class sfq 140:56 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 2814b 2p requeues 0
> > > > >   allot 1520
> > > > >
> > > > > class sfq 140:63 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 7570b 5p requeues 0
> > > > >   allot 1520
> > > > >
> > > > > class sfq 140:9a parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 6056b 4p requeues 0
> > > > >   allot 1448
> > > > >
> > > > > class sfq 140:f8 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 1310b 2p requeues 0
> > > > >   allot 528
> > > > >
> > > > > class sfq 140:1c7 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 3028b 2p requeues 0
> > > > >   allot 1520
> > > > >
> > > > > class sfq 140:269 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 4542b 3p requeues 0
> > > > >   allot 1304
> > > > >
> > > > > class sfq 140:2ff parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 6056b 4p requeues 0
> > > > >   allot -72
> > > > >
> > > > > class sfq 140:30d parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 1514b 1p requeues 0
> > > > >   allot 1520
> > > > >
> > > > > class sfq 140:326 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 1502b 1p requeues 0
> > > > >   allot 1520
> > > > >
> > > > > class sfq 140:3ad parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 1514b 1p requeues 0
> > > > >   allot 1520
> > > > >
> > > > > class sfq 140:3c5 parent 140:
> > > > >   (dropped 0, overlimits 0 requeues 0)
> > > > >   backlog 1560b 2p requeues 0
> > > > >   allot 1520

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