Quick Start: add basic QoS settings

docs/ch03-quick-start.rst

@@ -101,3 +101,64 @@ Commit changes, save the configuration, and exit configuration mode:
   Done
   vyos@vyos# exit
   vyos@vyos$
+
+Basic QoS
+---------
+
+The traffic policy subsystem provides an interface to Linux traffic control
+(tc_).
+
+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:`set traffic-policy shaper-hfsc`)
+
+See further information in the `QoS and Traffic Policy`_ chapter.
+
+.. _tc: http://en.wikipedia.org/wiki/Tc_(Linux)