experiment: add init_network method to NS3E2ENet

Add a new method init_network to NS3E2ENet that does some initialization
before the experiment is run. It should be called after all components
were added to the network.

experiments/pyexps/e2e_cc.py

@@ -189,5 +189,7 @@ for congestion_control in types_of_congestion_control:
             clients[num_simbricks_hosts - 1].node_config.app.is_last = True
             clients[num_simbricks_hosts - 1].wait = True
 
+            net.init_network()
+
             print(e.name)
             experiments.append(e)

experiments/pyexps/e2e_split.py

@@ -209,5 +209,8 @@ for congestion_control in types_of_congestion_control:
             clients[num_simbricks_hosts - 1].node_config.app.is_last = True
             clients[num_simbricks_hosts - 1].wait = True
 
+            left_net.init_network()
+            right_net.init_network()
+
             print(e.name)
             experiments.append(e)

experiments/simbricks/orchestration/simulators.py

@@ -954,31 +954,30 @@ class NS3E2ENet(NetSim):
                 self, e2e_sim.simbricks_component
             )
 
-    def instantiate(self):
-        pass
-
-    def run_cmd(self, env):
-        if self.first_run:
-            self.instantiate()
-            for topo in self.e2e_topologies:
-                topo.add_to_network(self)
+    def init_network(self) -> None:
+        # add all components from topologies to the network
+        for topo in self.e2e_topologies:
+            topo.add_to_network(self)
 
         for component in self.e2e_components:
-            if self.first_run:
-                component.resolve_paths()
+            component.resolve_paths()
 
+            # add all connected networks
+            for c in component.components:
+                if isinstance(c, e2e.E2ESimbricksNetworkNetIf):
+                    self.connect_network(c.simbricks_component)
+
+    def run_cmd(self, env):
+        # resolve all socket paths
+        for component in self.e2e_components:
             for c in component.components:
                 if isinstance(c, e2e.E2ESimbricksHost):
                     self.resolve_socket_paths(env, c)
                 elif isinstance(c, e2e.E2ESimbricksNetworkNetIf):
                     self.resolve_socket_paths(env, c)
-                    if self.first_run:
-                        self.connect_network(c.simbricks_component)
                 elif isinstance(c, e2e.E2ESimbricksNetworkNicIf):
                     self.resolve_socket_paths(env, c, True)
 
-        self.first_run = False
-
         params: tp.List[str] = []
         for component in self.e2e_components:
             params.append(component.ns3_config())