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From: Stef Coene <stef.coene@docum.org>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] shaping incoming with ingress
Date: Thu, 31 Jul 2003 09:46:32 +0000	[thread overview]
Message-ID: <marc-lartc-105964486302457@msgid-missing> (raw)
In-Reply-To: <marc-lartc-105960881709594@msgid-missing>

On Thursday 31 July 2003 05:00, Martin A. Brown wrote:
> Good questions Damion,
>
>  : I've noticed as of late, everyone saying 'you can't shape incoming
>  : traffic' but the best solution is to use the imq device.
>
> Well....(you'll love this) the reason everyone is saying "you can't shape
> incoming traffic" is because you can't shape incoming traffic (without
> IMQ).
>
> Well, in short, what we're really saying is that you can't control what
> you receive (without IMQ).  As the recipient of frames/packets, you have
> no control over how fast they arrive in your device's input queue.
You can shape outgoing packets because they are queued in a buffer before they 
are sended out.  You can shape because you can reorder packets in that 
buffer.  Incoming packets are not buffered, so you can't change the order.

>  : what happened to ingress /policer usage? is this not recommended
>  : anymore?
>
> There's nothing at all wrong with using an ingress policer.  I don't
> believe it's possible to attach any classes to the ingress qdisc*.  That
> is, the ingress qdisc only exists to allow the user to police inbound
> traffic.
>
> So, using the ingress qdisc as a dummy qdisc against which to attach a
> policing filter (which drops traffic over a given rate) is the only use of
> the ingress qdisc.
Indeed.  And policing is not shaping.  Policing is rate limiting while shaping 
can do more.  For example, shaping can borrow unused bandwidth in a 
controlled way between different flows.

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

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  parent reply	other threads:[~2003-07-31  9:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-07-30 23:45 [LARTC] shaping incoming with ingress Damion de Soto
2003-07-31  3:00 ` Martin A. Brown
2003-07-31  3:55 ` Rio Martin.
2003-07-31  5:50 ` smohan
2003-07-31  9:46 ` Stef Coene [this message]
2003-07-31  9:46 ` Stef Coene
2003-07-31  9:56 ` Rio Martin.
2003-07-31 11:34 ` Stef Coene

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