RE: R2Q and more

Linux Advanced Routing and Traffic Control

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Thanks for your answers!

I played with some values and I might add something. Please tell me if I am
wrong.

Overruling the QUANTUM parameter in a LEAF class makes the RATE parameter
useless. From my opinion QUANTUM is the parameter that is the most relevant.


e.g. 	CLASS A - RATE 64kbit - QUANTUM 1500
	CLASS B - RATE  8kbit - QUANTUM 3000

Class B gets twice the bandwidth that CLASS A receives. RATE is useless in
this case.

So you might establish some sort of a rule that the ratio of QUANTUMS equals
the ratio of the (real) RATEs of 2 LEAF CLASSES. BUT that is also wrong if
the ratio is bigger that 2-3. 

e.g.	CLASS A	QUANTUM 1500
	CLASS B	QUANTUM 6000

You would expect CLASS B to get 4 times the bandwidth that CLASS A gets. But
in fact ... the Ratio is somewhere around 2.8-3.0. (These tests were made on
a 256 kilobit bandwidth).
----------------------------------------------------------------------------

I agree that it is very important to set the RATE of the parent CLASS below
the value of the bandwidth. In my case - for a 256kbit bandwidth from my
ISP, 240kbit RATE works excellent

----------------------------------------------------------------------------

There is still a problem remained unsolved for me. 
(My connection works excellent after 6.00 PM until 10.00 AM. During the day
my ISP establishes some "rules" in which the connection is shared among some
clients.) You cannot tell the exact value of the bandwidth during the day.
It is very bursty. You might download with 240kbit for 1 minute and after
that the bandwidth might get to 64kbit, etc...

So I do not have a "standard" connection. Is it possible to split that
"bursty" bandwidth (as unpredictable as it is) among my friends in my LAN? 
I use esfq. Is there a way that HTB can auto-sense the parameters of the
bandwidth and reconfigure itself? I know that sounds real funny, but for me
it would be a dream to have such a traffic shaper. I do not have enough
money to buy a straight 256kbit connection :( 


Thanks again,

Mihai Vlad   



-----Original Message-----
From: lartc-admin@xxxxxxxxxxxxxxx [mailto:lartc-admin@xxxxxxxxxxxxxxx] On
Behalf Of Stef Coene
Sent: Monday, March 29, 2004 12:05 AM
To: lartc@xxxxxxxxxxxxxxx
Subject: Re:  R2Q and more

On Sunday 28 March 2004 21:18, Roy wrote:
> > Q2. What happens if the SUM of all the clients' class RATE (+
> the
> > default class RATE) is bigger than 256kbit? Will HTB work
> correctly?
> Yes.
> --------
> This is incorrect:
> of course it will work more or less, but nearly same as without any 
> shaping
It will work more then you think.  On the short term, traffic can be bursty
for the different classes, but each one will belimited to 8kbit.  But on the
long term, each class will get the same share of bandwidth.

> > Q3. What happens if the ISP does not guarantee a '"'full
> 256kbit'"'
> > bandwidth?
> > (Suppose that I set my Linux box to shape 256kbit and my ISP
> provides me
> > only 128kbit during high-traffic hours). Will HTB work
> correctly?
> Yes.
> -----
> For certain this is wrong, I dont understand why you say so, because 
> everybody knows that you must limit ceil to a bit lover than you get 
> from isp if you have unknown trafic you cant limit it.
Ok, my error.  I forgot about the "make sure YOU are the bottlleneck".  I
thought it was a variant on question Q2.

> > Q4. As far as I understood R2Q means the ratio between the RATE
> and the
> > QUANTUM of a class... Which is more '"'powerful'"'? The
> RATE, or the QUANTUM?
>
> > (e.g. ClassA---QUANTUM 3000---RATE 8kbit, or ClassB---QUANTUM 
> > 1500---RATE 16kbit)
>
> r2q is used to calculate the default quantum of a class: quantum =ate 
> / r2q But you can overrule this default quantum when you add a class.
> ------
> quantum is more powerfull and usefull. since rate of 8kbit is 
> insignificant speed anyway but it may be harder to calculate( didt 
> tested if quantum can completely replace rate effect) in your example 
> class A will get 2 times more bandwitch than class B
To be correct, it also depends on the packet size.  If you have packets of
1499 bytes in class B and 1500 bytes in class A, both class will get the
same rate.  Why?  Quantum for class B is 1500, so you can send 2 packets and
these
2 packets are counted as 1500 bytes.

> > Q5. The HTB Manual says that the sum of the LEAF CLASSES RATE
> must be
> > equal to the PARENT CLASS RATE. Is there such a rule for
> QUANTUMS?
> No
> ----
> seems correct,
> htb manual says nonsense,
> neither rates nether quantums need to be equal, but child sum rates 
> and quantums ONLY SHOULD be less or equal to parent.
> quantums for schild basicaly should be not higer than parent quantums, 
> else result may be starange.
I'm not sure but, isn't quanum only used for leaf classes?  So the quantum
of parent classes doesn't mather ?

Stef

--
stef.coene@xxxxxxxxx
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.openprojects.net
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-----Original Message-----
From: lartc-admin@xxxxxxxxxxxxxxx [mailto:lartc-admin@xxxxxxxxxxxxxxx] On
Behalf Of Roy
Sent: Monday, March 29, 2004 2:44 AM
To: lartc@xxxxxxxxxxxxxxx
Subject: Re:  R2Q and more

> > Q2. What happens if the SUM of all the clients' class RATE
(+
> the
> > default class RATE) is bigger than 256kbit? Will HTB
work
> correctly?
> Yes.
> --------
> This is incorrect:
> of course it will work more or less, but nearly same as without
any shaping
It will work more then you think.  On the short term, traffic can be bursty
for the different classes, but each one will belimited to 8kbit.  But on the
long term, each class will get the same share of bandwidth.
------
basicaly this may work if difference is not big,
but it was not working for me, I was trying to set rate 8kbit for everyone,
since the sum of rates was 3 times biger than parent ceil, trafic was
divided in unpredictable way.
then  I set rate to 1 kbit and everything worked well filling syslog by
warnings that quantum is too small.

logicaly this should not work because htb guarantee the rate amount trafic,
so what if there is not so much available?


> > Q5. The HTB Manual says that the sum of the LEAF CLASSES
RATE
> must be
> > equal to the PARENT CLASS RATE. Is there such a rule
for
> QUANTUMS?
> No
> ----
> seems correct,
> htb manual says nonsense,
> neither rates nether quantums need to be equal,
> but child sum rates and quantums ONLY SHOULD be less or equal
to parent.
> quantums for schild basicaly should be not higer than parent
quantums, else
> result may be starange.
I'm not sure but, isn't quanum only used for leaf classes?  So the quantum
of
parent classes doesn't mather ?
---------
You may be right, since I did not checked source code for this, but logicaly
quantum is very significant part
and shoud work everywhere, I suppose quantum is about same as cburst, but
even more significant,
sems  it is only way to divide bandwitch between classes with some
proportion.
-----------------
I found strange limitation, if class have leafs, then I cant attach sfq to
it.
where will go unclasified packets from that class? Into root's default?
Now I use dummy class for this purpose with filter which match on anything
Strange that htb have such limitation.


Stef

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