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Re: further CBQ/tc documentation

To: bert hubert <ahu@xxxxxxx>
Subject: Re: further CBQ/tc documentation
From: jamal <hadi@xxxxxxxxxx>
Date: Sat, 8 Dec 2001 15:43:05 -0500 (EST)
Cc: <lartc@xxxxxxxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>, <kuznet@xxxxxxxxxxxxx>, <netdev@xxxxxxxxxxx>
In-reply-to: <20011208205541.A15565@xxxxxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx

For starters, i think you need a defintions sections. Look at:

(eg what is a shaper etc and how trhings are placed together). At least
that will ensure that you dont sday things like "Prio cant shape".

It is a good model but may be insufficient given Linux TCs
capabilities. Email me when unsure.

Some other things:
- In your comment "Do not confuse this classless simple qdisc with the
classful PRIO one!". This is misleading:
the default 3 band FIFO queue is conceptually the same as the
default prio qdisc (the priomaps are identical). 3 bands; same
prioritization schemes.
- You really need to fix ingress section:
 it works for both forwarding and packets coming in to local sockets.
More importantly, It takes advantages of _all_ filter schemes
available for TC as well as the policing functionality (which sadly seemed
to have been replicated by someone in netfilter, wrongly if i may add ;->).
- You keep saying "reodering" -- dont know what that means. Reordering is
generally considered a Bad Thing(tm).

- your description of the "peakrate" (same in TBF as well as policing)

Well captured. It took ages to get this into peoples heads. This also
applies to CBQ.

- your description of "MTU"
Not very good description:
This is just what it literally says; maximum transmit unit;
A packet larger than this will be dropped. Default is 2K. For ethernet,
MTUs of 1500 bytes, this is fine; however, you should put a cautionary
statement here in regards to people having MTUs smaller than 2K (example
the lo device); they might find that all their packets greater than 2K
being dropped.

More later if dont get distracted.


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