diff --git a/scenarios/networking/dense_l2.yaml b/scenarios/networking/dense_l2.yaml
index 8bcdb0a..5a95f36 100644
--- a/scenarios/networking/dense_l2.yaml
+++ b/scenarios/networking/dense_l2.yaml
@@ -8,7 +8,7 @@ deployment:
   accommodation: [pair, double_room, density: 8, compute_nodes: 1]
 
 execution:
-  size: linear_progression
+  progression: linear
   tests:
   -
     title: Iperf TCP
diff --git a/scenarios/networking/dense_l3_east_west.yaml b/scenarios/networking/dense_l3_east_west.yaml
index 1918a15..1958108 100644
--- a/scenarios/networking/dense_l3_east_west.yaml
+++ b/scenarios/networking/dense_l3_east_west.yaml
@@ -7,7 +7,7 @@ deployment:
   accommodation: [pair, double_room, density: 8, compute_nodes: 1]
 
 execution:
-  size: linear_progression
+  progression: linear
   tests:
   -
     title: Iperf TCP
diff --git a/scenarios/networking/dense_l3_north_south.yaml b/scenarios/networking/dense_l3_north_south.yaml
index 7e75097..7ee6651 100644
--- a/scenarios/networking/dense_l3_north_south.yaml
+++ b/scenarios/networking/dense_l3_north_south.yaml
@@ -8,7 +8,7 @@ deployment:
   accommodation: [pair, double_room, density: 8, compute_nodes: 1]
 
 execution:
-  size: linear_progression
+  progression: linear
   tests:
   -
     title: Iperf TCP
diff --git a/scenarios/networking/full_l2.yaml b/scenarios/networking/full_l2.yaml
index 37cb265..e48ec2b 100644
--- a/scenarios/networking/full_l2.yaml
+++ b/scenarios/networking/full_l2.yaml
@@ -7,7 +7,7 @@ deployment:
   accommodation: [pair, single_room]
 
 execution:
-  size: quadratic_progression
+  progression: quadratic
   tests:
   -
     title: Iperf TCP
diff --git a/scenarios/networking/full_l3_east_west.yaml b/scenarios/networking/full_l3_east_west.yaml
index 3bc4f96..47dea54 100644
--- a/scenarios/networking/full_l3_east_west.yaml
+++ b/scenarios/networking/full_l3_east_west.yaml
@@ -7,7 +7,7 @@ deployment:
   accommodation: [pair, single_room]
 
 execution:
-  size: quadratic_progression
+  progression: quadratic
   tests:
   -
     title: Iperf TCP
diff --git a/scenarios/networking/full_l3_north_south.yaml b/scenarios/networking/full_l3_north_south.yaml
index 6e8dd07..8900cab 100644
--- a/scenarios/networking/full_l3_north_south.yaml
+++ b/scenarios/networking/full_l3_north_south.yaml
@@ -8,7 +8,7 @@ deployment:
   accommodation: [pair, single_room]
 
 execution:
-  size: quadratic_progression
+  progression: quadratic
   tests:
   -
     title: Iperf TCP
diff --git a/shaker/engine/server.py b/shaker/engine/server.py
index 964c89e..657008c 100644
--- a/shaker/engine/server.py
+++ b/shaker/engine/server.py
@@ -49,16 +49,16 @@ def _make_test_title(test):
     return re.sub(r'[^\x21-\x7e\x80-\xff]+', '_', s).lower()
 
 
-def _pick_agents(agents, size):
+def _pick_agents(agents, progression):
     # slave agents do not execute any tests
     agents = [a for a in agents.values() if a.get('mode') != 'slave']
 
-    if not size or size == 'full':
+    if not progression:
         yield agents
-    elif size == 'linear_progression':
+    elif progression in ['arithmetic', 'linear', 'linear_progression']:
         for i in range(len(agents)):
             yield agents[:i + 1]
-    elif size == 'quadratic_progression':
+    elif progression in ['geometric', 'quadratic', 'quadratic_progression']:
         n = len(agents)
         seq = [n]
         while n > 1:
@@ -75,8 +75,9 @@ def execute(quorum, execution, agents):
     for test in execution['tests']:
         LOG.debug('Running test %s on all agents', test)
         test_title = _make_test_title(test)
+        progression = execution.get('progression', execution.get('size'))
 
-        for selected_agents in _pick_agents(agents, execution.get('size')):
+        for selected_agents in _pick_agents(agents, progression):
             executors = dict((a['id'], executors_classes.get_executor(test, a))
                              for a in selected_agents)
 
diff --git a/tests/test_server.py b/tests/test_server.py
index a87d245..25d66e6 100644
--- a/tests/test_server.py
+++ b/tests/test_server.py
@@ -46,7 +46,7 @@ class TestServer(testtools.TestCase):
                 'id': i, 'mode': 'alone', 'node': 'uno',
             }
         picked = [set(a['id'] for a in arr)
-                  for arr in server._pick_agents(agents, 'full')]
+                  for arr in server._pick_agents(agents, None)]
         self.assertEqual([set(range(10))], picked)
 
     def test_pick_agents_full_filter_slaves(self):
@@ -59,7 +59,7 @@ class TestServer(testtools.TestCase):
                 'id': 'slave_%s' % i, 'mode': 'slave', 'node': 'uno',
             }
         picked = [set(a['id'] for a in arr)
-                  for arr in server._pick_agents(agents, 'full')]
+                  for arr in server._pick_agents(agents, None)]
         self.assertEqual([set('master_%s' % i for i in range(10))],
                          picked)
 
@@ -70,7 +70,7 @@ class TestServer(testtools.TestCase):
                 'id': i, 'mode': 'alone', 'node': 'uno',
             }
         picked = [set(a['id'] for a in arr)
-                  for arr in server._pick_agents(agents, 'linear_progression')]
+                  for arr in server._pick_agents(agents, 'linear')]
         self.assertEqual([set(range(i + 1)) for i in range(0, 10)],
                          picked)
 
@@ -82,7 +82,7 @@ class TestServer(testtools.TestCase):
             }
         picked = [set(a['id'] for a in arr)
                   for arr in server._pick_agents(agents,
-                                                 'quadratic_progression')]
+                                                 'quadratic')]
         self.assertEqual([set(range(1)), set(range(2)),
                           set(range(5)), set(range(10))],
                          picked)