Re: [LARTC] Anti-CBQ Statements in Howto

[bert hubert <ahu@ds9a.nl>]

On Thu, Dec 06, 2001 at 03:30:47PM -0500, Michael T. Babcock wrote:
> I find the negative attitude toward CBQ to be distracting and 
> non-professional in the HOWTO.  I've re-read it for the first time in 
> about a month and comments like "This can be configured in a variety of 
> ways, which I do not understand. Use HTB" do not encourage me about the 
> writer.

There is exactly one place that says 'use HTB :-)'. But I will remove it.

> This is not a personal critique, as I can imagine this being said on a 
> personal website, but as a generic HOWTO, this is out of place.  A 
> statement like "if you don't understand these options, you may find HTB 
> to be easier to follow" is professional and possibly more accurate.

Well, there are a lot of reasons why CBQ may not fit your needs. I really
want to downplay the 'holy grail' status it has achieved. New text:

	You may wonder what happens to traffic that is not classified by any
	of the two rules. It appears that in this case, data will then be
	processed within 1:0, and be unlimited. The unfiltered behaviour can
	be configured in a variety of ways, which have not yet been
	documented adequately. HTB is clearer in this respect, so you may
	prefer it.

> I've seen other documents that describe the options the author says he 
> doesn't understand whose authors like CBQ and/or believe it to be 
> well-designed.  I've had no real problems with it and don't actually 

Read linux/net/sched/sch_cbq.c for some enlightenment.

> see HTB as being easier to configure or follow if you leave the 'knobs' 
> on CBQ to their suggested defaults.

If you see CBQ working well, you are probably on an empty 10 or 100mbit
segment, talking directly to the switch, or using a plain-old-modem with a
fixed bitrate. In other cases, CBQ is 'saved' because it actually contains
token bucket filters, which ARE pretty accurate.

CBQ relies on being dequeued at a well known rate, which is simply not
always the case. Furthermore, often there is no 'well known rate', for
example when using a PPP-over-Ethernet modem over a userspace socket.

Anyway, 'use HTB :-)' may indeed not be appropriate and has been changed,
thanks.

Regards,

bert hubert

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