[LARTC] Re: tc n00b

[Jonathan Gazeley <jonathan.gazeley@bristol.ac.uk>]

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Hi Abhijit,

Thanks a lot for your advice - I didn't realise that the source IP was 
re-written before the traffic was shaped.

I have attached the script I wrote. As I said before, the download limit 
does successfully work and each client (I am using 2 test clients) gets 
512kbit each. However the upload is still unlimited. But I don't believe 
this is currently due to the source IP being re-written - tc itself 
doesn't like my commands. They were literally copied and pasted from the 
download commands and altered as appropriate, as you see in the script. 
When I run this script, for each iteration of lines 48-49 produces the 
following error:

137.222.235.125
Error: Qdisc "tbf" is classless.
Error: Qdisc "1:" is classless.
Unknown filter "1:", hence option "protocol" is unparsable

I don't really understand that error - especially as the identical code 
does work for the download limits. If you can offer any more help, I'd 
be most grateful.

Cheers,
Jonathan


Abhijit Menon-Sen wrote:
> Hello Jonathan.
>
> At 2007-07-30 12:40:00 +0100, jonathan.gazeley@bristol.ac.uk wrote:
>   
>> So far I have managed to get the download limits working. However I
>> need to shape on both interfaces so I recycled the same code to apply
>> to uploads but it didn't work and I can't figure out why
>>     
>
> That's not really enough information to try to debug your problem, but I
> can think of one problem you might encounter. Since you're doing NAT for
> your clients, you should be aware that the source address is rewritten
> (i.e. in nat/POSTROUTING) _before_ egress QoS processing.
>
> So if you're trying to classify outgoing traffic based on their source
> IP address, it won't work.
>
> One alternative is to mark packets from the internal network (i.e. use
> -J MARK --set-mark N in mangle/PREROUTING), and write a filter on the
> outgoing interface that assigns traffic to classes based on how it's
> marked (u32 match mark ...). (If you want more details, ask.)
>
> (If anyone has other suggestions, I would be interested in them too.)
>
> -- ams
>   

-- 
------------------------
Jonathan Gazeley
Wireless & VPN Team
Information Systems & Computing
University of Bristol
------------------------


[-- Attachment #2: newtcscript.sh --]
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#!/bin/sh
## JONATHAN'S TC SCRIPT

# LAN interfaces
LAN=eth0
WAN=eth1

# Maximum global uplink and downlink in mbit/s
GLOBAL_DOWN=100
GLOBAL_UP=100

# Maximum per-user download & upload speed in kbit/s
DOWNLINK=512
UPLINK=256

# Subnets to be stamped down upon, delimited by spaces
SUBNETS='235'

# IP range in each subnet
LOW_IP=1
HIGH_IP=125

#-----------------Don't mess with stuff below---------------|
#-----------------this line or you'll break it--------------|

# Flush existing rules
tc qdisc del dev $LAN root
tc qdisc del dev $WAN root

# Create root class for 100mbit interface - total traffic can't exceed this
tc qdisc add dev $LAN root handle 1: cbq avpkt 1000 bandwidth ${GLOBAL_DOWN}mbit
tc qdisc add dev $WAN root handle 1: cbq avpkt 1000 bandwidth ${GLOBAL_UP}mbit

# Set useful counters
jcount=1
icount=1
total=0

# Apply rules for all included subnets
for j in $SUBNETS
do
 for i in `seq $LOW_IP $HIGH_IP`
  do
   total=$((total+1))
   echo 137.222.$j.$i
   tc class add dev $LAN parent 1: classid 1:$total tbf rate ${DOWNLINK}kbit allot 1500 prio 5 bounded isolated 
   tc filter add dev $LAN parent 1: protocol ip prio 16 u32 match ip dst 137.222.$j.$i flowid 1:$total
   tc class add dev $wAN parent 1: classid 1:$total tbf rate ${UPLINK}kbit allot 1500 prio 5 bounded isolated
   tc filter add dev $wAN parent 1: protocol ip prio 16 u32 match ip src 137.222.$j.$i flowid 1:$total
   i=i+1
  done
j=j+1
done
echo
echo $total miscreants were stamped down upon. Good work Pokey!
echo Their IP addresses were in the following ranges:
for j in $SUBNETS
 do
  echo 137.222.$j.$LOW_IP-$HIGH_IP
 done

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