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Re: dummy as IMQ replacement

To: Thomas Graf <tgraf@xxxxxxx>
Subject: Re: dummy as IMQ replacement
From: jamal <hadi@xxxxxxxxxx>
Date: 31 Jan 2005 15:18:35 -0500
Cc: netdev@xxxxxxxxxxx, Nguyen Dinh Nam <nguyendinhnam@xxxxxxxxx>, Remus <rmocius@xxxxxxxxxxxxxx>, Andre Tomt <andre@xxxxxxxx>,, Andy Furniss <andy.furniss@xxxxxxxxxxxxx>, Damion de Soto <damion@xxxxxxxxxxxx>
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Organization: jamalopolous
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On Mon, 2005-01-31 at 13:15, Thomas Graf wrote:

> I haven't left ns sim so far, my calculations are based on some of the
> linux specific cc modifications though, i.e. I modified ns sim a bit
> to provide the same information. I'm thinking about moving to umlsim,
> it should provide a better real world simulation.

The problem is if theres any bugs in the way algos are implemented in
Linux you are influenced by that truth. Starting with ns and then
validating on Linux is a great way to do it.

> Sounds good, we could put up a ematch csum for validation and a eaction
> for recomputation. I'll wait for your code to show up.

Cross your fingers; worst case by weekend i should get something out.

> > Essentially on ingress create state; i have to find my notes to give you
> > precise answer. But one of the parameters was to select the level of
> > state tracking (such as "track IP only" - not sure how doable that is
> > with contrack)
> So you want to have a generic conntrack action capable of dynamically
> taking whatever information into account that the user requests? This
> remembers me of the esfq effort which could benefit from this, it
> extends sfq to take the definition for a flow as a parameter. We could
> share some code here.

I dont think contrack was designed for this kind of effort. If we totaly
fail to do it using contrack then we could go a different path.
sfq already stores some rough view of the state; not sure if it can
benefit from this.

> > Stateless NAT doesnt really need contracking. pedit (taught to speak
> > english) + eaction csum should do it.
> Right, given we don't need any reverse translation. Still it would be
> neat to set the conntrack attributes so one could use iptables later
> on, I'm not sure how doable this is though.

If you are NATing (stateless) you should enter rules for both
directions; Maybe we could write a wrapper where user only enters
outgoing rule and that automatically generates the incoming rule as

> Something different...
> This sounds all very good but I think we're still sucessfully ignoring
> one of the most important points, usability. 


> Most modifications over
> the last few months have complicated things, introduced different behaviour
> depending on compile time options and userspace tools which are either
> outdated or having features being completely undocumented. Some of the
> recent additions don't even show up in the usage text of iproute2. So
> I think we should at least part time focus a little more on the big
> picture and make things consitent and more useable. At least 50% of the
> functionaility currently in mainline is completely unused because nobody
> knows about it. I'm in no way against any of the recent additions but
> maybe we can also put some more effort into usability.

I think the eactions etc are adding a lot of value towards usability.
Hasso Tepper was ealrier complaining about this same issue. 
As an example, I think u32 and ematches would improve a great deal now
and be more understandable. True, work/time still needs to be invested.


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