initial refactoring
diff --git a/oltbase.py b/oltbase.py
new file mode 100644
index 0000000..642d5c2
--- /dev/null
+++ b/oltbase.py
@@ -0,0 +1,114 @@
+import oftest.base_tests as base_tests
+import oftest.packet as scapy
+
+import ofp
+import time
+
+
+class OltBaseTest(base_tests.SimpleDataPlane):
+
+    def installDoubleTaggingRules(s_vlan_id, c_vlan_id, cookie=42):
+
+        # upstream flow rule
+        match = ofp.match()
+        match.oxm_list.append(ofp.oxm.in_port(onu_port))
+        if device_type == "cpqd":
+            match.oxm_list.append(ofp.oxm.vlan_vid(value=ofp.OFPVID_NONE))
+            actions = [
+                ofp.action.push_vlan(ethertype=0x8100),
+                ofp.action.set_field(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT | c_vlan_id)),
+                ofp.action.set_field(ofp.oxm.vlan_pcp(0))
+            ]
+        else:  # "pmc", "normal"
+            match.oxm_list.append(ofp.oxm.vlan_vid(value=ofp.OFPVID_PRESENT))
+            match.oxm_list.append(ofp.oxm.vlan_pcp(value=0))
+            actions = [
+                ofp.action.set_field(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT | c_vlan_id))
+            ]
+        cookie += 1
+
+        # push inner vlan (c-vlan) for upstream
+        request = ofp.message.flow_add(
+            table_id=test_param_get("table", 0),
+            cookie=cookie,
+            match=match,
+            instructions=[
+                ofp.instruction.apply_actions(actions=actions),
+                ofp.instruction.goto_table(1)],
+            buffer_id=ofp.OFP_NO_BUFFER,
+            priority=1000)
+
+        self.controller.message_send(request)
+        do_barrier(self.controller)
+        verify_no_errors(self.controller)
+
+        # push outer vlan (s-vlan) for upstream
+        match = ofp.match()
+        match.oxm_list.append(ofp.oxm.in_port(onu_port))
+        match.oxm_list.append(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT | c_vlan_id))
+        match.oxm_list.append(ofp.oxm.vlan_pcp(0))
+        cookie += 1
+
+        request = ofp.message.flow_add(
+            table_id=test_param_get("table", 1),
+            cookie=cookie,
+            match=match,
+            instructions=[
+                ofp.instruction.apply_actions(
+                    actions=[
+                        ofp.action.push_vlan(ethertype=0x8100),
+                        ofp.action.set_field(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT | s_vlan_id)),
+                        ofp.action.set_field(ofp.oxm.vlan_pcp(0)),
+                        ofp.action.output(port=olt_port)]),
+            ],
+            buffer_id=ofp.OFP_NO_BUFFER,
+            priority=1000)
+
+        self.controller.message_send(request)
+        do_barrier(self.controller)
+        verify_no_errors(self.controller)
+        cookie += 1
+
+        # strip outer vlan (s-vlan) for downstream
+        match = ofp.match()
+        match.oxm_list.append(ofp.oxm.in_port(olt_port))
+        match.oxm_list.append(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT | s_vlan_id))
+        match.oxm_list.append(ofp.oxm.vlan_pcp(0))
+        request = ofp.message.flow_add(
+            table_id=test_param_get("table", 0),
+            cookie=cookie,
+            match=match,
+            instructions=[
+                ofp.instruction.apply_actions(
+                    actions=[ofp.action.pop_vlan()]),
+                ofp.instruction.goto_table(1)],
+            buffer_id=ofp.OFP_NO_BUFFER,
+            priority=1000)
+
+        self.controller.message_send(request)
+        do_barrier(self.controller)
+        verify_no_errors(self.controller)
+
+        # rewrite inner vlan (c-vlan) to default (0) for downstream
+        match = ofp.match()
+        match.oxm_list.append(ofp.oxm.in_port(olt_port))
+        match.oxm_list.append(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT | c_vlan_id))
+        match.oxm_list.append(ofp.oxm.vlan_pcp(0))
+        cookie += 1
+
+        request = ofp.message.flow_add(
+            table_id=test_param_get("table", 1),
+            cookie=cookie,
+            match=match,
+            instructions=[
+                ofp.instruction.apply_actions(
+                    actions=[
+                        ofp.action.pop_vlan(),
+                        ofp.action.output(port=onu_port)])
+            ],
+            buffer_id=ofp.OFP_NO_BUFFER,
+            priority=1000)
+
+        self.controller.message_send(request)
+        do_barrier(self.controller)
+        verify_no_errors(self.controller)