LARTC - Jul 2004 - ebtables and HTB bandwidth shaping - change frame or packet sizes

Hallo 

I have recently implemented a Fedora core 2 Linux box with ebtables and HTB
for doing some traffic shaping

What I would like to know is if there are some way to change the packet or
frame sizes of the traffic that passes through this type of system. If  I am
understand correctly this will also help with the bandwidth, maybe not on
throughput but definitely on continues throughput if the data line is
running in the 99% utilization.

We had a demo on our data line with a system called packeteer, and it seems
as if this product intercepts the packet and changes the packet or frame
size and therefore the traffic will not hog the bandwidth that easily. This
how ever is a very expensive product and if one can do it on Linux why not.

I have more or less the same queues setup than what was the case for the
packeteer demo and currently I do not see that big a change than with
packeteer.

Can someone give me some advice and if at all possible give me an indication
of how to go about to do this.

Groete / Regards
Thomas

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>What I would like to know is if there are some way to change the packet or
>frame sizes of the traffic that passes through this type of system. If  I am
>understand correctly this will also help with the bandwidth, maybe not on
>throughput but definitely on continues throughput if the data line is
>running in the 99% utilization.
>
>We had a demo on our data line with a system called packeteer, and it seems
>as if this product intercepts the packet and changes the packet or frame
>size and therefore the traffic will not hog the bandwidth that easily. This
>how ever is a very expensive product and if one can do it on Linux why not.
>  
>
I''m not quite sure what you are asking for, but perhaps you mean 
fragmenting packets so that they are smaller (ie 5 small packets rather 
than 1 large one?)

The trick here is either to change every machine to have a lower MTU in 
your office (can be tedious), or look at using "MSS clamping".  This
is
something that you can do in iptables.  Search google, and I think in 
the LARTC for more details.  There are other tricks you can do with MTU

Packeteer is perhaps the premier product out there, but you should be 
able to do 90% of the same things with Linux, and for many cases far 
*more* than with packeteer.  I think there are a few people who will 
offer paid support as well, so you are not necessarily disadvantaged 
here either.

Out of curiousity, what does a packeteer box set you back these days?  
My old firm was looking at buying one, I was thinking about biding 
against them...

Ed W
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