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# Random Detect
#
# This Qos module uses DSMARK and GRED to provide a policy
# similar to Cisco Weighted Random Detect.
#
# See Almesberger, Werner; Hadi Salim, Jamal; Kuznetsov, Alexey
# "Differentiated Services on Linux"
# http://www.almesberger.net/cv/papers/18270721.pdf
#
# **** License ****
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# This code was originally developed by Vyatta, Inc.
# Portions created by Vyatta are Copyright (C) 2008 Vyatta, Inc.
# All Rights Reserved.
# **** End License ****
package Vyatta::Qos::RandomDetect;
use strict;
use warnings;
require Vyatta::Config;
use Vyatta::Qos::Util qw/getRate getAutoRate getTime/;
# default values for different precedence levels
my @default_fields = (
{ 'min-threshold' => 9, 'mark-probability' => 1/2 },
{ 'min-threshold' => 10, 'mark-probability' => 5/9 },
{ 'min-threshold' => 11, 'mark-probability' => .1 },
{ 'min-threshold' => 12, 'mark-probability' => 2/3 },
{ 'min-threshold' => 13, 'mark-probability' => .1 },
{ 'min-threshold' => 14, 'mark-probability' => 7/9 },
{ 'min-threshold' => 15, 'mark-probability' => 5/6 },
{ 'min-threshold' => 16, 'mark-probability' => 8/9 },
);
# Create a new instance based on config information
sub new {
my ( $that, $config, $name ) = @_;
my $level = $config->setLevel();
my $rate = $config->returnValue("bandwidth");
die "$level bandwidth configuration missing" unless $rate;
my @precedence = getPrecedence( $level );
my $self = {};
my $class = ref($that) || $that;
bless $self, $class;
$self->{_rate} = $rate;
$self->{_precedence} = \@precedence;
return $self;
}
sub getPrecedence {
my ( $level ) = @_;
my $config = new Vyatta::Config;
my @precedence;
for ( my $i = 0 ; $i <= 7 ; $i++ ) {
my $defaults = $default_fields[$i];
my %param;
foreach my $field (qw(max-threshold average-packet queue-limit),
keys %$defaults) {
my $val = $config->returnValue($field);
if ( !defined $val ) {
$param{$field} = $defaults->{$field};
} elsif ( $field eq 'mark-probability' ) {
$param{$field} = 1 / $val;
} else {
$param{$field} = $val;
}
}
$precedence[$i] = \%param;
}
return @precedence;
}
sub commands {
my ( $self, $dev ) = @_;
my $root = 1;
my $precedence = $self->{_precedence};
my $rate = getAutoRate( $self->{_rate}, $dev );
# 1. setup DSMARK to convert DSCP to tc_index
printf "qdisc add dev %s root handle %x:0 dsmark indices 8 set_tc_index\n",
$dev, $root;
# 2. use tcindex filter to convert tc_index to precedence
#
# Precedence Field: the three leftmost bits in the TOS octet of an IPv4
# header.
printf "filter add dev %s parent %x:0 protocol ip prio 1 ",
$dev, $root;
print "tcindex mask 0xe0 shift 5\n";
# 3. Define GRED with unmatched traffic going to index 0
printf "qdisc add dev %s parent %x:0 handle %x:0 gred ",
$dev, $root, $root+1;
print "setup DPs 8 default 0 grio\n";
# set VQ parameters
for ( my $i = 0 ; $i <= 7 ; $i++ ) {
my $param = $precedence->[$i];
my $qmin = $param->{'min-threshold'};
my $qmax = $param->{'max-threshold'};
my $qlimit = $param->{'queue-limit'};
my $avgpkt = $param->{'average-packet'};
my $prob = $param->{'mark-probability'};
$qmax = 18 unless $qmax;
$avgpkt = 1024 unless $avgpkt;
$qlimit = 4 * $qmax unless $qlimit;
printf "qdisc change dev %s handle %x:0 gred", $dev, $root+1, $i;
printf " limit %d min %d max %d avpkt %d",
$qlimit * $avgpkt, $qmin * $avgpkt, $qmax * $avgpkt, $avgpkt;
printf " burst %d bandwidth %d probability %f DP %d prio %d\n",
( 2 * $qmin + $qmax ) / 3, $rate, $prob, $i, 8-$i;
}
}
# Walk configuration tree and look for changed nodes
# The configuration system should do this but doesn't do it right
sub isChanged {
my ( $self, $name ) = @_;
my $config = new Vyatta::Config;
$config->setLevel("qos-policy random-detect $name");
return 'bandwidth' if ( $config->isChanged('bandwidth') );
my %precedenceNodes = $config->listNodeStatus('precedence');
while ( my ( $pred, $status ) = each %precedenceNodes ) {
return "precedence $pred" if ( $status ne 'static' );
my $defaults = $default_fields[0];
foreach my $attr (keys %$defaults) {
return "precedence $pred $attr"
if ( $config->isChanged("precedence $pred $attr") );
}
}
return; # false
}
1;
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