xref: /aosp_15_r20/external/iproute2/README.iproute2+tc (revision de1e4e894b0c224df933550f0afdecc354b238c4)

iproute2+tc*

It's the first release of Linux traffic control engine.


NOTES.
* csz scheduler is inoperational at the moment, and probably
  never will be repaired but replaced with h-pfq scheduler.
* To use "fw" classifier you will need ipfwchains patch.
* No manual available. Ask me, if you have problems (only try to guess
  answer yourself at first 8)).


Micro-manual how to start it the first time
-------------------------------------------

A. Attach CBQ to eth1:

tc qdisc add dev eth1 root handle 1: cbq bandwidth 10Mbit allot 1514 cell 8 \
avpkt 1000 mpu 64

B. Add root class:

tc class add dev eth1 parent 1:0 classid 1:1 cbq bandwidth 10Mbit rate 10Mbit \
allot 1514 cell 8 weight 1Mbit prio 8 maxburst 20 avpkt 1000

C. Add default interactive class:

tc class add dev eth1 parent 1:1 classid 1:2 cbq bandwidth 10Mbit rate 1Mbit \
allot 1514 cell 8 weight 100Kbit prio 3 maxburst 20 avpkt 1000 split 1:0 \
defmap c0

D. Add default class:

tc class add dev eth1 parent 1:1 classid 1:3 cbq bandwidth 10Mbit rate 8Mbit \
allot 1514 cell 8 weight 800Kbit prio 7 maxburst 20 avpkt 1000 split 1:0 \
defmap 3f

etc. etc. etc. Well, it is enough to start 8) The rest can be guessed 8)
Look also at more elaborated example, ready to start rsvpd,
in rsvp/cbqinit.eth1.


Terminology and advices about setting CBQ parameters may be found in Sally Floyd
papers.


Pairs X:Y are class handles, X:0 are qdisc handles.
weight should be proportional to rate for leaf classes
(I choosed it ten times less, but it is not necessary)

defmap is bitmap of logical priorities served by this class.

E. Another qdiscs are simpler. F.e. let's join TBF on class 1:2

tc qdisc add dev eth1 parent 1:2 tbf rate 64Kbit buffer 5Kb/8 limit 10Kb

F. Look at all that we created:

tc qdisc ls dev eth1
tc class ls dev eth1

G. Install "route" classifier on root of cbq and map destination from realm
1 to class 1:2

tc filter add dev eth1 parent 1:0 protocol ip prio 100 route to 1 classid 1:2

H. Assign routes to 10.11.12.0/24 to realm 1

ip route add 10.11.12.0/24 dev eth1 via whatever realm 1

etc. The same thing can be made with rules.
I still did not test ipchains, but they should work too.


Setup and code example of BPF classifier and action can be found under
examples/bpf/, which should explain everything for getting started.


Setup of rsvp and u32 classifiers is more hairy.
If you read RSVP specs, you will understand how rsvp classifier
works easily. What's about u32... That's example:


#! /bin/sh

TC=/home/root/tc

# Setup classifier root on eth1 root (it is cbq)
$TC filter add dev eth1 parent 1:0 prio 5 protocol ip u32

# Create hash table of 256 slots with ID 1:
$TC filter add dev eth1 parent 1:0 prio 5 handle 1: u32 divisor 256

# Add to 6th slot of hash table rule to select tcp/telnet to 193.233.7.75
# direct it to class 1:4 and prescribe to fall to best effort,
# if traffic violate TBF (32kbit,5K)
$TC filter add dev eth1 parent 1:0 prio 5 u32 ht 1:6: \
	match ip dst 193.233.7.75 \
	match tcp dst 0x17 0xffff \
	flowid 1:4 \
	police rate 32kbit buffer 5kb/8 mpu 64 mtu 1514 index 1

# Add to 1th slot of hash table rule to select icmp to 193.233.7.75
# direct it to class 1:4 and prescribe to fall to best effort,
# if traffic violate TBF (10kbit,5K)
$TC filter add dev eth1 parent 1:0 prio 5 u32 ht 1:: \
	sample ip protocol 1 0xff \
	match ip dst 193.233.7.75 \
	flowid 1:4 \
	police rate 10kbit buffer 5kb/8 mpu 64 mtu 1514 index 2

# Lookup hash table, if it is not fragmented frame
# Use protocol as hash key
$TC filter add dev eth1 parent 1:0 prio 5 handle ::1 u32 ht 800:: \
	match ip nofrag \
	offset mask 0x0F00 shift 6 \
	hashkey mask 0x00ff0000 at 8 \
	link 1:


Alexey Kuznetsov
[email protected]