[LARTC] mysterious rebounce in htb

[LARTC] mysterious rebounce in htb

[Andreas Hasenack]

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Attached is a graph obtained with ethereal where after time +/-45s there is
a rebounce which I can't explain.

Setup is this:
- my machine starts to generate traffic at maximum speed against a
  target machine (using nc < /dev/zero here and nc -l > /dev/null there)
- traffic pattern is:
   0s: dst port 2500 (red)
  20s: dst port 8000 (blue)
  40s: kill port 2500 traffic
  60s: kill port 8000 traffic
- htb is limiting that traffic to 100mbps at all times (see below for
  htb configuration)

Could that bounce be a result of some wrong configuration I have? Or
some other traffic interfering with my measurements? I used a "host
10.0.16.10" filter in ethereal, and since the bounce is "compensated" in
the other traffic I don't think it was some external interference, but
who knows.6

htb config is created by this script. Note I created two root classes so
that my regular work on this desktop doesn't interfere with the
measurements and tests I'm performing (or so I hope):

#!/bin/bash
DEV=eth0
WWWPORT=8000
SMTPPORT=2500
MAPI=10.0.16.10
tc qdisc del dev $DEV root > /dev/null 2>&1

# root qdisc
tc qdisc add dev $DEV handle 1: root htb default 2

# root classes
tc class add dev $DEV classid 1:1 parent 1: htb rate 100kbps
tc class add dev $DEV classid 1:2 parent 1: htb rate 90mbit
tc qdisc add dev $DEV handle 2: parent 1:2 sfq perturb 10

# a/www
tc class add dev $DEV classid 1:10 parent 1:1 htb rate 30kbps ceil 100kbps prio 0
tc qdisc add dev $DEV handle 10: parent 1:10 sfq perturb 10

# a/smtp
tc class add dev $DEV classid 1:11 parent 1:1 htb rate 10kbps ceil 100kbps prio 0
tc qdisc add dev $DEV handle 20: parent 1:11 sfq perturb 10

# b
tc class add dev $DEV classid 1:12 parent 1:1 htb rate 60kbps ceil 100kbps
tc qdisc add dev $DEV handle 30: parent 1:12 sfq perturb 10

# qualquer coisa indo para a mapi8 cai na classe 1:1
tc filter add dev $DEV parent 1:0 prio 10 protocol ip u32 \
	match ip dst $MAPI/32 \
	flowid 1:1

# on 1:1: a/www -> 1:10
tc filter add dev $DEV parent 1:1 prio 5 protocol ip u32 \
	match ip dst $MAPI/32 \
	match ip protocol 0x06 0xff \
	match ip dport $WWWPORT 0xffff \
	flowid 1:10

# on 1:1: a/smtp -> 1:11
tc filter add dev $DEV parent 1:1 prio 5 protocol ip u32 \
	match ip dst $MAPI/32 \
	match ip protocol 0x06 0xff \
	match ip dport $SMTPPORT 0xffff \
	flowid 1:11

# on 1:1: b (telnet, for example) -> 1:12
tc filter add dev $DEV parent 1:1 prio 5 protocol ip u32 \
	match ip dst $MAPI/32 \
	match ip protocol 0x06 0xff \
	match ip dport 23 0xffff \
	flowid 1:12



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