Add QoS chapter

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+QoS and Traffic Policy
+======================
+
+The traffic policy subsystem provides an interface to Linux traffic control.
+
+One common use of traffic policy is to limit bandwidth for an interface. In
+the example below we limit bandwidth for our LAN connection to 200 Mbit
+download and out WAN connection to 50 Mbit upload:
+
+.. code-block:: sh
+
+  set traffic-policy shaper WAN-OUT bandwidth '50Mbit'
+  set traffic-policy shaper WAN-OUT default bandwidth '50%'
+  set traffic-policy shaper WAN-OUT default ceiling '100%'
+  set traffic-policy shaper WAN-OUT default queue-type 'fair-queue'
+
+  set traffic-policy shaper LAN-OUT bandwidth '200Mbit'
+  set traffic-policy shaper LAN-OUT default bandwidth '50%'
+  set traffic-policy shaper LAN-OUT default ceiling '100%'
+  set traffic-policy shaper LAN-OUT default queue-type 'fair-queue'
+
+Resulting in the following configuration:
+
+.. code-block:: sh
+
+  traffic-policy {
+      shaper WAN-OUT {
+          bandwidth 50Mbit
+          default {
+              bandwidth 50%
+              ceiling 100%
+              queue-type fair-queue
+          }
+      }
+      shaper LAN-OUT {
+          bandwidth 200Mbit
+          default {
+              bandwidth 50%
+              ceiling 100%
+              queue-type fair-queue
+          }
+      }
+  }
+
+Once defined, a traffic policy can be applied to each interface using the
+interface-level `traffic-policy` directive:
+
+.. code-block:: sh
+
+  set interfaces ethernet eth0 traffic-policy out 'WAN-OUT'
+  set interfaces ethernet eth1 traffic-policy out 'LAN-OUT'
+
+Note that a traffic policy can also be defined to match specific traffic flows
+using class statements.
+
+VyOS 1.2 (Crux) also supports HFSC_:
+
+.. code-block:: sh
+
+ set traffic-policy shaper-hfsc
+
+See further information on the QoS_ page.
+
+.. _HFSC: https://en.wikipedia.org/wiki/Hierarchical_fair-service_curve
+.. _QoS: https://wiki.vyos.net/wiki/QoS
diff --git a/docs/index.rst b/docs/index.rst
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--- a/docs/index.rst
+++ b/docs/index.rst
@@ -37,6 +37,8 @@ as a router and firewall platform for cloud deployments.
 
 .. include:: ch09-vpn.rst
 
+.. include:: ch10-qos.rst
+
 Indices and tables
 ==================