[ovs-dev] [PATCH] Document per-port round-robin during controller rate limiting.

Ben Pfaff blp at nicira.com
Tue Sep 22 16:33:44 UTC 2009

CC: Peter Balland <peter at nicira.com>

Bug #2072.
 vswitchd/ovs-vswitchd.conf.5.in |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/vswitchd/ovs-vswitchd.conf.5.in b/vswitchd/ovs-vswitchd.conf.5.in
index 12fea6c..d41983e 100644
--- a/vswitchd/ovs-vswitchd.conf.5.in
+++ b/vswitchd/ovs-vswitchd.conf.5.in
@@ -547,6 +547,19 @@ These settings configure how the virtual switch applies a ``token
 bucket'' to limit the rate at which packets in unknown flows are
 forwarded to the OpenFlow controller for flow-setup processing.  This
 feature prevents a single bridge from overwhelming a controller.
+In addition, when a high rate triggers rate limiting, Open vSwitch
+queues controller packets for each port, up to a total of \fIburst\fR
+packets across all ports on the bridge.  A port queue balancing
+algorithm prevents a single port on a bridge from monopolizing the
+resources for forwarding packets for unknown flows on a given bridge.
+Open vSwitch maintains two such packet rate-limiters per bridge.  One
+of these applies to packets sent up to the controller because they do
+not correspond to any flow.  The other applies to packets sent up to
+the controller by request through flow actions.  When both
+rate-limiters are filled with packets, the actual rate that packets
+are sent to the controller is up to twice the specified rate.
 .IP "\fBbridge.\fIname\fB.controller.rate-limit=\fIrate\fR"
 .IQ "\fBmgmt.rate-limit=\fIrate\fR"
 Limits the maximum rate at which packets will be forwarded to the

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