From 410e94afe308549e097137f4ef3241ebcf1d4ed5 Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <stephen.hemminger@vyatta.com>
Date: Mon, 19 Jul 2010 16:13:28 -0700
Subject: Add check for random-detect on slow speed class
The calculation of random-detect queue parameters is based on recommended
values from RFC. If allowed bandwidth is too small, the queue will be
too small to be useable. In that case just fail.
---
lib/Vyatta/Qos/ShaperClass.pm | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
(limited to 'lib')
diff --git a/lib/Vyatta/Qos/ShaperClass.pm b/lib/Vyatta/Qos/ShaperClass.pm
index 439e404..6b474e6 100644
--- a/lib/Vyatta/Qos/ShaperClass.pm
+++ b/lib/Vyatta/Qos/ShaperClass.pm
@@ -117,17 +117,28 @@ sub rateCheck {
exit 1;
}
- my $qlimit = $self->{_limit};
- if (defined($qlimit) && $self->{_qdisc} eq 'random-detect') {
+ if ($self->{_qdisc} eq 'random-detect') {
my $avg = 1024;
my $qmax = ( $rate * 100 ) / 8000;
- if ($qlimit * $avg < $qmax) {
+ my $qlimit = $self->{_limit};
+ if (defined($qlimit) && $qlimit * $avg < $qmax) {
print STDERR "Configuration error in: $level\n";
printf STDERR
"The queue limit (%d) is too small, must be greater than %d when using random-detect\n",
$level, $qmax / $avg;
exit 1;
}
+
+ # The assumptions about average packet size and allowable latency
+ # result in limit on available bandwidth
+ #
+ # 2 * Avg pkt = (BW * Latency) / 8 bit/byte
+ # 16K bits = BW * .1 sec
+ if ($qmax < $avg) {
+ print STDERR "Configuration error in: $level\n";
+ die
+"Random-detect queue type requires effective bandwidth of 160 Kbit/sec or greater\n";
+ }
}
}
--
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