Hi Andy,
I made the dumpfile and will send it to you in a separate private email. I
cannot see anything suspicious, but maybe I am not looking for the right
thing.
Same goes for netstat -s | grep retrans : The count does not rise during the
transfer.
For the modem, here is what it says:
down up
Bit-rate (fast) : 15694 915
Bit-rate (relative cap.) : 100 % 100 %
Bit-rate (max) : 15694 915
FEC error (fast) : 7116 0
CRC error (fast) : 13421 0
HEC error (fast) : 5051 0
Noise margin : 8.3 dB 8.5 dB
Attenuation : 16.0 dB 12.8 dB
Transmit power : 22.3 dBm 12.3 dBm
First channel : 64 33
Last channel : 505 59
Channel gaps : 95 110 127 188 191 243 291 348
All this is very irritating. I don´t think it depends on the remote host,
because it appears on every remote I try.
Are you sure that tc makes everything right? I would say it?s the easiest
point of failure.
Do you have any more ideas?
Thanks,
Philipp
> -----Ursprüngliche Nachricht-----
> Von: lartc-bounces@xxxxxxxxxxxxxxx [mailto:lartc-bounces@xxxxxxxxxxxxxxx]
> Im Auftrag von Andy Furniss
> Gesendet: Dienstag, 14. November 2006 20:39
> An: Philipp Leusmann
> Cc: lartc@xxxxxxxxxxxxxxx
> Betreff: Re: AW: AW: Why did I need strange ceiling settings?
> (fullversion)
>
> Philipp Leusmann wrote:
> > Hi andy,
> >
> > I reset the ceiling to 600kbit and get same same bad results as before.
> Also
> > I set all classes to use the same quantum which is mtu (it is 1488
> here).
> > Here is the output you requested:
>
> >
> > class htb 1:103 parent 1:1 leaf 801b: prio 2 quantum 1488 rate 250000bit
> > ceil 600000bit burst 1724b/8 mpu 0b overhead 0b cburst 1899b/8 mpu 0b
> > overhead 0b level 0
> > Sent 27111784 bytes 28505 pkts (dropped 0, overlimits 0)
> > rate 286232bit 34pps backlog 2p
> > lended: 12193 borrowed: 16310 giants: 0
> > tokens: -83395 ctokens: -41934
>
> That is strange - assuming that upload is tcp, there are no drops and
> only a backlog of 2.
>
> When uploading you are somewhat dependant on the size of the window
> advertised by the far end - also loss, which in this case is not by htb,
> will make your cwind small.
>
> I think what you need to do is tcpdump -s 100 -w dumpfile the connection
> from the start and have a look/ post what's going on.
>
> Another way to see if it's external loss is on the sender do a few
>
> netstat -s | grep retrans
>
> and look at the counter.
>
> Small chance there could be some window scaling mismatch caused by a
> broken router in the way.
>
> The loss could be isp/target server dropping or -
>
> You mentioned a nominal upload rate of 1mbit which you don't reach. If
> you are synced at a low target SNR margin then some modems will doggedly
> hold the line and take the loss - others will drop and resync (often at
> a similar rate as the extra noise that causes the resync is gone when it
> retrains). I have to limit my downrate to 75% of 6db speed and it still
> drops sometimes. My up is solid, though, as it's limited to 50% due to
> the product I am on (448/up to 8128 - horribly asymmetric if I could
> sync at 8128)
>
> As to why shaping on/off makes such a difference - I am not sure, you
> are backlogged so there is some limiting happening, so maybe the higher
> speeds achieved without htb rely on being able to burst out full speed
> whenever loss is low.
>
> Andy.
>
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