[techtalk] Download throttling?

Harald Welte laforge at sunbeam.franken.de
Mon Sep 4 13:26:10 EST 2000


On Sun, Sep 03, 2000 at 09:47:29PM +0100, Conor Daly wrote:
> 
> Just half a page on traffic control but it raises some questions.  I'm
> using a similar setup:
> 486/66 firewall/router/dial-on-demand with ipmasq for the net with clients
> and server behind it.  
> 
> Now, one can set up a tunnel from a source IP to a destination 
> IP through a device (real or virtual) and limit the bandwith, burst size
> and queue size.  Queueing cannot be implemented on a virtual device so the
> virtual must be mapped to a real device.  So, the questions arise...

? I don't understand. Is the tunnel a necessity? You really want to do
traffic shaping for a tunnel? Which kind of tunnel are You talking about
L2TP? PPTP? IPsec? cipe?

You don't need to set up a tunnel for the scheduling / queuing stuff.

> 1.  Can multiple virtual devices map to a single real device (eg ppp0)?

of course.

> 2.  If ipmasq changes all packets to an outbound ip address on the way to
> ppp0, do you end up with all traffic going down a single tunnel?

This depends on the kind of tunnel You use. If You set up multiple tunnels
from behind your Masq gate to one tunneling server outside than You cannot
use GRE based tunnels, for example :)

> 3.  Do you end up having to do forwarding to different tunnels for each
> client / protocol first and then ip masq the tunnels on their way to ppp0
> (maybe bind the tunnels to eth0 rather than to ppp0)?

Please can 

> 4.  Can you adjust the bandwidth parameters on the fly or only at setup of
> the tunnel?  Can a single client on-line get the benefit of the full
> bandwidth and get throttled back when another user goes on-line?

Why do You want to setup tunnels for Your bandwidth control? I still don't
understand. 

The usual setup is to have some classifier, which divides the packets into
different classes (let's say a "slow" class and a priorized "fast" class)

You can then treat each of these classes differently, let's say use
different scheduling algorithms for each of the classes

> 5.  Does all this mean an 'orrible mess of a routing table?

no. and You can have 255 routing tables in 2.2, and have ip rules select
which routing table to use for which packet class.

> Conor Daly <conor.daly at oceanfree.net>

-- 
Live long and prosper
- Harald Welte / laforge at sunbeam.franken.de    http://www.sunbeam.franken.de
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