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* [LARTC] CBQ broken in RedHat 8.0?
From: Neil Aggarwal @ 2002-10-26 23:53 UTC (permalink / raw)
  To: lartc

Hello all:

Is CBQ broken in RedHat 8.0?
It seems that my CBQ is not using priorities.

I have this setup:

Internet <-> DSL Modem <-> Linux router <-> IP Switch <-> Laptop

The Linux computer is running a fresh, unmodified installation
of RedHat 8.0?

On the Linux computer, eth0 points to the DSL modem
and eth1 points to my internal network.
The Linux compter runs DHCP and masquerade.

I want to make sure that ssh traffic is prioritied above
all other traffic.

After reading the HOWTO and the wondershaper code, I set-up the following
tc rules on the Linux computer:

# The downlink speed, in kilobits
DOWNLINK00
# The uplink speed, in kilobits
UPLINK\x100
# The device to control
DEV=eth0
# Install the root CBQ at 1:0
tc qdisc add dev $DEV root handle 1: cbq avpkt 1000 bandwidth 10mbit

# Add a cbq at 1:1 to limit the total bandwidth to the uplink speed
tc class add dev $DEV parent 1: classid 1:1 cbq rate ${UPLINK}kbit allot
1500 prio 1 bounded isolated

# Create a queue for the high priority traffic
tc class add dev $DEV parent 1:1 classid 1:10 cbq rate ${UPLINK}kbit allot
1600 prio 1 avpkt 1000 bounded isolated
tc qdisc add dev $DEV parent 1:10 handle 10: sfq perturb 10

# Create a queue for the low priority traffic
tc class add dev $DEV parent 1:1 classid 1:20 cbq rate $[9*$UPLINK/10]kbit
allot 1600 prio 2 avpkt 1000 bounded isolated
tc qdisc add dev $DEV parent 1:20 handle 20: sfq perturb 10

# Filter ssh traffic into the high prioirty queue
tc filter add dev $DEV parent 1:0 protocol ip prio 10 u32 match ip sport 22
0xffff  flowid 1:10
tc filter add dev $DEV parent 1:0 protocol ip prio 10 u32 match ip dport 22
0xffff  flowid 1:10

# Filter the rest of the traffic into the low priority queue, policing the
rate and dropping any overflow packets
tc filter add dev $DEV parent 1:0 protocol ip prio 13 u32 match ip dst
0.0.0.0/0 police rate $[9*$UPLINK/10]kbit burst 10k drop flowid 1:20

# Police the incoming traffic to the rate we specified
tc qdisc add dev $DEV handle ffff: ingress
tc filter add dev $DEV parent ffff: protocol ip prio 50 u32 match ip src
0.0.0.0/0 police rate ${DOWNLINK}kbit burst 10k drop flowid :1

What I am expecting from these rules is that the ssh traffic will take
complete priority over
anything else.  Other traffic will only get what is left over.

To test this, I set-up a large FTP upload from my laptop to a machine over
the Internet
and then set up and ssh transfer of a large file to another machine.
After letting things settle down, I ran my traffic control script.

After a while, I ran this command to see the results:
tc -s qdisc ls dev eth0

Here is what I got:
 qdisc ingress ffff: ----------------
 Sent 514549 bytes 9924 pkts (dropped 0, overlimits 0)

 qdisc sfq 20: quantum 1514b perturb 10sec
 Sent 10522893 bytes 7296 pkts (dropped 0, overlimits 0)
 backlog 5p

 qdisc sfq 10: quantum 1514b perturb 10sec
 Sent 7648142 bytes 5449 pkts (dropped 0, overlimits 0)

 qdisc cbq 1: rate 10Mbit (bounded,isolated) prio no-transmit
 Sent 18173599 bytes 12771 pkts (dropped 120, overlimits 18412)
 backlog 5p
  borrowed 0 overactions 0 avgidle 624 undertime 0

The low priority traffic is getting more traffic sent thru.
This is not what I wanted.

Any ideas why this is happening?

Thanks,
	Neil.

--
Neil Aggarwal
JAMM Consulting, Inc.    (972) 612-6056, http://www.JAMMConsulting.com
Custom Internet Development    Websites, Ecommerce, Java, databases

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