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Date:      Tue, 01 May 2001 23:04:32 -0700
From:      Julian Elischer <julian@elischer.org>
To:        =?iso-8859-1?Q?R=E9mi?= Guyomarch <rguyom@pobox.com>
Cc:        Gunther Schadow <gunther@aurora.regenstrief.org>, snap-users@kame.net, freebsd-net@freebsd.org, ipfilter@coombs.anu.edu.au, altq@csl.sony.co.jp
Subject:   Re: The future of ALTQ, IPsec & IPFILTER playing together ...
Message-ID:  <3AEFA370.28562F63@elischer.org>
References:  <3AEEEE79.8F7CC7B0@aurora.regenstrief.org> <3AEEF26B.C6850070@isi.edu> <3AEEF59D.3D5622DE@aurora.regenstrief.org> <20010501205741.A30269@diabolic-cow.chatgris.net> <3AEF0E6A.2E9B34A0@aurora.regenstrief.org> <20010501235602.B30269@diabolic-cow.chatgris.net>

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Rémi Guyomarch wrote:
> 
> On Tue, May 01, 2001 at 07:28:42PM +0000, Gunther Schadow wrote:
> > Rémi Guyomarch wrote:
> >
> > > IIRC you can put a bandwidth limiter on a virtual interface (this is
> > > even the only solution to use ALTQ on tun or ppp devices) and thus
> > > provide a queue which can be managed by ALTQ.
> >
> > Aha! A Light! How is that done? Can you give more specifics?
> 
> Look at docs/TIPS.txt in the altq-3.0 release, point 1.9 :
> 
> ...
> 1.9 Tun Driver
>     Although altq-3.0 supports the tun driver, it is a bit tricky to
>     control the tun device.
> 
>     When ppp transmits packets the tun interface is not a bottleneck
>     but the serial port is the bottleneck.  As a result, packets are
>     queued in the output queue of ppp and the buffer in the kernel
>     as shown in the following figure. (a queued packet is shown as X.)
> 
>                                  ppp
>       app ---+              +-->[ XXX]--+
>              |              |           |
>    user      |              |           |
>    ==========|==============|===========|=====
>    kernel    |              |           |
>              |   +------+   |           |
>              +-->|      |---+           +->[ XX]--> sio
>                  +------+                  line
>                    tun0                  discipline
> 
>     To control traffic at the tun interface, rate-limit the tun
>     interface by a token-bucket regulator to shift the queueing point
>     to the tun device as shown in the following figure.
> 
>                                  ppp
>       app ---+              +-->[    ]--+
>              |              |           |
>    user      |              |           |
>    ==========|==============|===========|=====
>    kernel    |              |           |
>              |   +------+   |           |
>              +-->| XXXXX|---+           +->[   ]--> sio
>                  +------+^tbr              line
>                    tun0                  discipline
> 
>     Note that ppp usually compress packets so that the throughput at
>     the tun interface will be much higher than the line rate.


the above picture is only true for ppp
if you use mpd it is as follows:


>                            
>       app ---+            
>              |             
>    user      |              
>    ==========|================================
>    kernel    |                         
>              |   +------+        ppp   
>              +-->|      |---+-->[    ]--+->[   ]--> sio
>                  +------+^tbr              line
>                    ng0                  discipline
> 


> ...
> 


-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000-2001
---> X_.---._/  
            v

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