[LARTC] HTB mpu and overhead settings for PPPoE ADSL?

[LARTC] HTB mpu and overhead settings for PPPoE ADSL?

[Stefan Gold]

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Hello,

I'm using HTB to shape my outgoing traffic over a ADSL-link with PPPoE with a 
nominal bandwidth of 128kbit/s. My goal is to favour small packets like ACKs 
and interactive services like ssh; in other words, I want to achieve low 
lantency.

If there are some big packets going over the wire, everything works fine. But 
if there are many small packets saturating my uplink, I get pings of 1000ms 
and above. To minimize this effect I've set the HTB qdisc rate to 100kbit/s. 
But even now, throttling my uplink to lower than 80% of physical bandwidth, 
pings go up to 800ms in some cases.

Today I've noticed, that two additional parameters have been added recently to 
the HTB-shaper: mpu and overhead. Are this new parameters suitable for 
solving my problem?
Which are smart values for this two settings? I'm shaping the ppp-device 
directly, not the ethernet-device on which the dsl-modem is connected and I'm 
using the kernel pppoe driver (if this is important for you to know).

Thanks 

Stefan

- -- 
In a free world nobody needs Windows and Gates.
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Re: [LARTC] HTB mpu and overhead settings for PPPoE ADSL?

[Andy Furniss]

Stefan Gold wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Hello,
> 
> I'm using HTB to shape my outgoing traffic over a ADSL-link with PPPoE with a 
> nominal bandwidth of 128kbit/s. My goal is to favour small packets like ACKs 
> and interactive services like ssh; in other words, I want to achieve low 
> lantency.
> 
> If there are some big packets going over the wire, everything works fine. But 
> if there are many small packets saturating my uplink, I get pings of 1000ms 
> and above. To minimize this effect I've set the HTB qdisc rate to 100kbit/s. 
> But even now, throttling my uplink to lower than 80% of physical bandwidth, 
> pings go up to 800ms in some cases.
> 
> Today I've noticed, that two additional parameters have been added recently to 
> the HTB-shaper: mpu and overhead. Are this new parameters suitable for 
> solving my problem?
> Which are smart values for this two settings? I'm shaping the ppp-device 
> directly, not the ethernet-device on which the dsl-modem is connected and I'm 
> using the kernel pppoe driver (if this is important for you to know).
> 

You could use Ed Wildgooses' patch -

http://mailman.ds9a.nl/pipermail/lartc/2004q2/012752.html

But you need to know your ppp overhead - which may be hard unless you 
can get a cell count out of your modem.

http://www.mail-archive.com/lartc@mailman.ds9a.nl/msg06895.html

Andy.


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