more elegant definition of paths between client/router and router/server

config/topo/topo_1

@@ -1,5 +1,5 @@
 leftSubnet:10.0.
 rightSubnet:10.1.
-path_0:10,10,4
+path_c2r_0:10,10,4
-path_1:40,30,4
+path_c2r_1:40,30,4
 topoType:MultiIf

config/topo/topo_2

@@ -1,5 +1,6 @@
 leftSubnet:10.0.
 rightSubnet:10.1.
-path_0:100,20,4
+path_c2r_0:100,20,4
-path_1:1,20,4
+path_c2r_1:1,20,4
+path_r2s_0:10,20,10
 topoType:MultiIf

config/topo/topo_3

@@ -0,0 +1,5 @@
+leftSubnet:10.0.
+rightSubnet:10.1.
+path_c2r_0:100,20,4
+path_r2s_0:10,20,10
+topoType:MultiIf

config/topo/topo_4

@@ -0,0 +1,8 @@
+leftSubnet:10.0.
+rightSubnet:10.1.
+path_c2r_0:100,20,4
+path_c2r_1:100,20,4
+path_c2r_2:100,20,4
+path_r2s_0:10,20,10
+path_r2s_1:10,20,10
+topoType:MultiIf

config/topo/topo_5

@@ -0,0 +1,8 @@
+leftSubnet:10.0.
+rightSubnet:10.1.
+path_c2r_0:100,20,4
+path_c2r_1:100,20,4
+path_r2s_0:10,20,10
+path_r2s_1:10,20,10
+path_r2s_2:10,20,10
+topoType:MultiIf

core/experiment.py

@@ -179,24 +179,24 @@ class Experiment(object):
             self.topo.command_to(self.topo_config.client, "{} link set dev {} priority {}".format(
                 Experiment.IP_BIN, self.topo_config.get_client_interface(0), priority_path_0))
             self.topo.command_to(self.topo_config.router, "{} link set dev {} priority {}".format(
-                Experiment.IP_BIN, self.topo_config.get_router_interface_to_switch(0), priority_path_0))
+                Experiment.IP_BIN, self.topo_config.get_router_interface_to_client_switch(0), priority_path_0))
             self.topo.command_to(self.topo_config.client, "{} link set dev {} priority {}".format(
                 Experiment.IP_BIN, self.topo_config.get_client_interface(1), priority_path_1))
             self.topo.command_to(self.topo_config.router, "{} link set dev {} priority {}".format(
-                Experiment.IP_BIN, self.topo_config.get_router_interface_to_switch(1), priority_path_1))
+                Experiment.IP_BIN, self.topo_config.get_router_interface_to_client_switch(1), priority_path_1))
 
         backup_path_0 = self.experiment_parameter.get(ExperimentParameter.BACKUP_PATH_0)
         if int(backup_path_0) > 0:
             self.topo.command_to(self.topo_config.client,
                 self.topo_config.interface_backup_command(self.topo_config.get_client_interface(0)))
             self.topo.command_to(self.topo_config.router,
-                self.topo_config.interface_backup_command(self.topo_config.get_router_interface_to_switch(0)))
+                self.topo_config.interface_backup_command(self.topo_config.get_router_interface_to_client_switch(0)))
         backup_path_1 = self.experiment_parameter.get(ExperimentParameter.BACKUP_PATH_1)
         if int(backup_path_1) > 0:
             self.topo.command_to(self.topo_config.client,
                 self.topo_config.interface_backup_command(self.topo_config.get_client_interface(1)))
             self.topo.command_to(self.topo_config.router,
-                self.topo_config.interface_backup_command(self.topo_config.get_router_interface_to_switch(1)))
+                self.topo_config.interface_backup_command(self.topo_config.get_router_interface_to_client_switch(1)))
 
     def run_userspace_path_manager(self):
         """
@@ -364,7 +364,7 @@ class Experiment(object):
         count = self.experiment_parameter.get(ExperimentParameter.PING_COUNT)
         for i in range(0, self.topo_config.client_interface_count()):
             cmd = self.ping_command(self.topo_config.get_client_ip(i),
-                 self.topo_config.get_server_ip(), n=count)
+                 self.topo_config.get_server_ip(interface_index=0), n=count)
             logging.info(cmd)
             self.topo.command_to(self.topo_config.client, cmd)
 

core/topo.py

@@ -17,12 +17,22 @@ class NetemAt(object):
         return "netem at {} ({}) will be {}".format(self.at, self.delta, self.cmd)
 
 
+def get_bandwidth_delay_product_divided_by_mtu(delay, bandwidth):
+    """
+    With delay in ms, bandwidth in Mbps
+    """
+    rtt = 2 * float(delay)
+    bandwidth_delay_product = (float(bandwidth) * 125000.0) * (rtt / 1000.0)
+    return int(math.ceil(bandwidth_delay_product * 1.0 / 1500.0))
+
+
 class LinkCharacteristics(object):
     """
     Network characteristics associated to a link
 
     Attributes:
         id              the identifier of the link
+        link_type       type of the link
         delay           the one-way delay introduced by the link in ms
         queue_size      the size of the link buffer, in packets
         bandwidth       the bandwidth of the link in Mbps
@@ -31,8 +41,9 @@ class LinkCharacteristics(object):
         netem_at        list of NetemAt instances applicable to the link
         backup          integer indicating if this link is a backup one or not (useful for MPTCP)
     """
-    def __init__(self, id, delay, queue_size, bandwidth, loss, backup=False):
+    def __init__(self, id, link_type, delay, queue_size, bandwidth, loss, backup=0):
         self.id = id
+        self.link_type = link_type
         self.delay = delay
         self.queue_size = queue_size
         self.bandwidth = bandwidth
@@ -45,10 +56,7 @@ class LinkCharacteristics(object):
         """
         Get the bandwidth-delay product in terms of packets (hence, dividing by the MTU)
         """
-        rtt = 2 * float(self.delay)
+        return get_bandwidth_delay_product_divided_by_mtu(self.delay, self.bandwidth)
-        """ Since bandwidth is in Mbps and rtt in ms """
-        bandwidth_delay_product = (float(self.bandwidth) * 125000.0) * (rtt / 1000.0)
-        return int(math.ceil(bandwidth_delay_product * 1.0 / 1500.0))
 
     def buffer_size(self):
         """
@@ -116,6 +124,8 @@ class LinkCharacteristics(object):
         Notably used by BottleneckLink
         """
         return {
+            "link_id": self.id,
+            "link_type": self.link_type,
             "bw": float(self.bandwidth),
             "delay": "{}ms".format(self.delay),
             "loss": float(self.loss),
@@ -124,13 +134,14 @@ class LinkCharacteristics(object):
 
     def __str__(self):
         return """
+Link type: {}
 Link id: {}
     Delay: {}
     Queue Size: {}
     Bandwidth: {}
     Loss: {}
     Backup: {}
-        """.format(self.id, self.delay, self.queue_size, self.bandwidth, self.loss, self.backup) + \
+        """.format(self.link_type, self.id, self.delay, self.queue_size, self.bandwidth, self.loss, self.backup) + \
             "".join(["\t {} \n".format(n) for n in self.netem_at])
 
 
@@ -139,13 +150,11 @@ class TopoParameter(Parameter):
     RIGHT_SUBNET = "rightSubnet"
     NETEM_AT = "netem_at_"
     CHANGE_NETEM = "changeNetem"
-    SERVER_PATHS = "serverPaths"
 
     DEFAULT_PARAMETERS = {
         LEFT_SUBNET: "10.1.",
         RIGHT_SUBNET: "10.2.",
         CHANGE_NETEM: "false",
-        SERVER_PATHS: "1",
     }
 
     def __init__(self, parameter_filename):
@@ -184,34 +193,63 @@ class TopoParameter(Parameter):
 
         logging.info(self.link_characteristics[link_id].netem_at)
 
+    def parse_link_id_and_type(self, key):
+        """
+        The key of a path must have the following format:
+            path_{link_type}_{ID}
+
+        Note that several links can have the same ID, several links can have the same
+        link_type, but the tuple (link_type, ID) is unique.
+        """
+        _, link_type, link_id = key.split("_")
+        return link_type, int(link_id)
+
+    def parse_link_characteristics(self, value):
+        """
+        The format of a link characteristic is one of the following:
+            - "{delay},{queue_size},{bandwidth},{loss_perc},{is_backup}"
+            - "{delay},{queue_size},{bandwidth},{loss_perc}"
+            - "{delay},{queue_size},{bandwidth}"
+            - "{delay},{bandwidth}"
+
+        When not specified, default values are the following:
+            - queue_size: get_bandwidth_delay_product_divided_by_mtu(delay, bandwidth)
+            - loss_perc: 0
+            - is_backup: 0
+
+        Return
+            delay, bandwidth, queue_size, loss_perc, is_backup
+        """
+        loss_perc, is_backup = 0.0, 0
+        c = value.split(",")
+        if len(c) == 2:
+            delay, bw = float(c[0]), float(c[1])
+            return delay, bw, get_bandwidth_delay_product_divided_by_mtu(delay, bw), loss_perc, is_backup
+        if len(c) == 3:
+            return float(c[0]), float(c[2]), int(c[1]), loss_perc, is_backup
+        if len(c) == 4:
+            return float(c[0]), float(c[2]), int(c[1]), float(c[3]), is_backup
+        if len(c) == 5:
+            return float(c[0]), float(c[2]), int(c[1]), float(c[3]), int(c[4])
+
+        raise ValueError("Invalid link characteristics: {}".format(value))
+
     def load_link_characteristics(self):
         """
-        CAUTION: the path_i in config file is not taken into account. Hence place them in
+        Load the path characteristics
-        increasing order in the topo parameter file!
         """
-        i = 0
         for k in sorted(self.parameters):
-            # TODO FIXME rewrite this function
             if k.startswith("path"):
-                tab = self.parameters[k].split(",")
+                try:
-                bup = False
+                    link_type, link_id = self.parse_link_id_and_type(k)
-                loss = "0.0"
+                    delay, bw, queue_size, loss_perc, is_backup = self.parse_link_characteristics(
-                if len(tab) == 5:
+                        self.parameters[k])
-                    loss = tab[3]
+                except ValueError as e:
-                    bup = tab[4].lower() == 'true'
+                    logging.error("Ignored path {}: {}".format(k, e))
-                if len(tab) == 4:
-                    try:
-                        loss = float(tab[3])
-                        loss = tab[3]
-                    except ValueError:
-                        bup = tab[3].lower() == 'true'
-                if len(tab) == 3 or len(tab) == 4 or len(tab) == 5:
-                    path = LinkCharacteristics(i, tab[0],
-                            tab[1], tab[2], loss, bup)
-                    self.link_characteristics.append(path)
-                    i = i + 1
                 else:
-                    logging.warning("Ignored path {}".format(self.parameters[k]))
+                    path = LinkCharacteristics(link_id, link_type, delay, bw,
+                            queue_size, loss_perc, backup=is_backup)
+                    self.link_characteristics.append(path)
 
     def __str__(self):
         s = "{}".format(super(TopoParameter, self).__str__())
@@ -248,7 +286,8 @@ class BottleneckLink(object):
         topo_builder.add_link(self.bs2, self.bs3)
 
     def get_bs_name(self, index):
-        return "{}_{}_{}".format(BottleneckLink.BOTTLENECK_SWITCH_NAME_PREFIX, self.link_characteristics.id, index)
+        return "{}_{}_{}_{}".format(BottleneckLink.BOTTLENECK_SWITCH_NAME_PREFIX, 
+            self.link_characteristics.link_type, self.link_characteristics.id, index)
 
     def reinit_variables(self):
         # Required to retrieve actual nodes
@@ -534,15 +573,33 @@ class TopoConfig(object):
         """
         raise NotImplementedError()
 
+    def server_interface_count(self):
+        """
+        Return the number of server's interfaces, without lo
+        """
+        raise NotImplementedError()
+
     def get_client_interface(self, client_index, interface_index):
         """
         Return the interface with index `interface_index` of the client with index `client_index` 
         """
         raise NotImplementedError()
 
-    def get_router_interface_to_switch(self, index):
+    def get_server_interface(self, server_index, interface_index):
         """
-        Return the router's interface to switch with index `index`
+        Return the interface with index `interface_index` of the server with index `server_index` 
+        """
+        raise NotImplementedError()
+
+    def get_router_interface_to_client_switch(self, index):
+        """
+        Return the router's interface to client's switch with index `index`
+        """
+        raise NotImplementedError()
+
+    def get_router_interface_to_server_switch(self, index):
+        """
+        Return the router's interface to server's switch with index `index`
         """
         raise NotImplementedError()
 

topos/multi_interface.py

@@ -11,41 +11,86 @@ class MultiInterfaceTopo(Topo):
         self.client = self.add_client()
         self.server = self.add_server()
         self.router = self.add_router()
-        self.client_switches = []
+        self.c2r_client_switches = []
-        self.server_switches = []
+        self.c2r_router_switches = []
-        for l in self.topo_parameter.link_characteristics:
+        self.r2s_router_switches = []
-            self.client_switches.append(self.add_client_side_switch(l))
+        self.r2s_server_switches = []
-            self.add_link(self.client,self.client_switches[-1])
-            self.server_switches.append(self.add_router_side_switch(l))
-            self.add_bottleneck_link(self.client_switches[-1], self.server_switches[-1], link_characteristics=l)
-            self.add_link(self.server_switches[-1],self.router)
 
-        for i in range(int(self.topo_parameter.get(TopoParameter.SERVER_PATHS))):
+        # Add client - router links
+        for l in self.get_client_to_router_links():
+            self.c2r_client_switches.append(self.add_c2r_client_side_switch(l))
+            self.add_link(self.client, self.c2r_client_switches[-1])
+            self.c2r_router_switches.append(self.add_c2r_router_side_switch(l))
+            self.add_bottleneck_link(self.c2r_client_switches[-1], self.c2r_router_switches[-1], link_characteristics=l)
+            self.add_link(self.c2r_router_switches[-1], self.router)
+
+        # Special case: if there is no specified link between router and server, directly connect them!
+        if len(self.get_router_to_server_links()) > 0:
+            for l in self.get_router_to_server_links():
+                self.r2s_router_switches.append(self.add_r2s_router_side_switch(l))
+                self.add_link(self.router, self.r2s_router_switches[-1])
+                self.r2s_server_switches.append(self.add_r2s_server_side_switch(l))
+                self.add_bottleneck_link(self.r2s_router_switches[-1], self.r2s_server_switches[-1], link_characteristics=l)
+                self.add_link(self.r2s_server_switches[-1], self.server)
+        else:
             self.add_link(self.router, self.server)
+            
 
-    def add_client_side_switch(self, link):
+    def get_client_to_router_links(self):
-        return self.add_switch("{}{}".format(MultiInterfaceTopo.SWITCH_NAME_PREFIX, 2 * link.id))
+        return [l for l in self.topo_parameter.link_characteristics if l.link_type == "c2r"]
 
-    def add_router_side_switch(self, link):
+    def get_router_to_server_links(self):
-        return self.add_switch("{}{}".format(MultiInterfaceTopo.SWITCH_NAME_PREFIX, 2 * link.id + 1))
+        return [l for l in self.topo_parameter.link_characteristics if l.link_type == "r2s"]
+
+    def add_c2r_client_side_switch(self, link):
+        return self.add_switch("{}c2r{}".format(MultiInterfaceTopo.SWITCH_NAME_PREFIX, 2 * link.id))
+
+    def add_c2r_router_side_switch(self, link):
+        return self.add_switch("{}c2r{}".format(MultiInterfaceTopo.SWITCH_NAME_PREFIX, 2 * link.id + 1))
+
+    def add_r2s_router_side_switch(self, link):
+        return self.add_switch("{}r2s{}".format(MultiInterfaceTopo.SWITCH_NAME_PREFIX, 2 * link.id))
+
+    def add_r2s_server_side_switch(self, link):
+        return self.add_switch("{}r2s{}".format(MultiInterfaceTopo.SWITCH_NAME_PREFIX, 2 * link.id + 1))
 
     def __str__(self):
-        s = "Simple multiple interface topolgy \n"
+        s = "Simple multiple interface topology \n"
         i = 0
-        n = len(self.topo_parameter.link_characteristics)
+        nc = len(self.get_client_to_router_links())
-        for p in self.topo_parameter.link_characteristics:
+        ns = len(self.get_router_to_server_links())
-            if i == n // 2:
+        m = max(nc, ns)
-                if n % 2 == 0:
+        skipped = 0
-                    s = s + "c            r-----s\n"
+        for i in range(0, m):
-                    s = s + "|--sw----sw--|\n"
+            if i == m // 2:
+                if m % 2 == 0:
+                    s = s + "c                r--sw---bl---sw--s\n"
+                    s = s + " \-sw---bl---sw-/\n"
                 else:
-                    s = s + "c--sw----sw--r-----s\n"
+                    s = s + "c--sw---bl---sw--r--sw---bl---sw--s\n"
             else:
-                s = s + "|--sw----sw--|\n"
+                if i < m // 2:
-
+                    if (nc == m and ns + skipped == m) or (ns == m and nc + skipped == m):
-            i = i + 1
+                        s = s + " /-sw---bl---sw-\ /-sw---bl---sw-\ \n"
+                    elif nc == m:
+                        s = s + " /-sw---bl---sw-\ \n"
+                        skipped += 1
+                    else:
+                        s = s + "                  /-sw---bl---sw-\ \n"
+                        skipped += 1
+                else:
+                    if (nc == m and ns + skipped == m) or (ns == m and nc + skipped == m):
+                        s = s + " \-sw---bl---sw-/ \-sw---bl---sw-/ \n"
+                    elif nc == m:
+                        s = s + " \-sw---bl---sw-/ \n"
+                        skipped += 1
+                    else:
+                        s = s + "                  \-sw---bl---sw-/ \n"
+                        skipped += 1
+        
         return s
 
+
 class MultiInterfaceConfig(TopoConfig):
     NAME = "MultiIf"
 
@@ -53,7 +98,7 @@ class MultiInterfaceConfig(TopoConfig):
         super(MultiInterfaceConfig, self).__init__(topo, param)
 
     def configure_routing(self):
-        for i, l in enumerate(self.topo.client_switches):
+        for i, l in enumerate(self.topo.c2r_client_switches):
             cmd = self.add_table_route_command(self.get_client_ip(i), i)
             self.topo.command_to(self.client, cmd)
 
@@ -66,7 +111,7 @@ class MultiInterfaceConfig(TopoConfig):
                     i)
             self.topo.command_to(self.client, cmd)
 
-        for i in range(int(self.topo.topo_parameter.get(TopoParameter.SERVER_PATHS))):
+        for i, l in enumerate(self.topo.r2s_server_switches):
             cmd = self.add_table_route_command(self.get_server_ip(i), i)
             self.topo.command_to(self.server, cmd)
 
@@ -96,7 +141,7 @@ class MultiInterfaceConfig(TopoConfig):
         netmask = "255.255.255.0"
 
         links = self.topo.get_link_characteristics()
-        for i, l in enumerate(self.topo.client_switches):
+        for i, l in enumerate(self.topo.c2r_client_switches):
             cmd = self.interface_up_command(self.get_client_interface(0, i), self.get_client_ip(i), netmask)
             self.topo.command_to(self.client, cmd)
             client_interface_mac = self.client.intf(self.get_client_interface(0, i)).MAC()
@@ -106,23 +151,38 @@ class MultiInterfaceConfig(TopoConfig):
                 cmd = self.interface_backup_command(self.get_client_interface(0, i))
                 self.topo.command_to(self.client, cmd)
 
-        for i, l in enumerate(self.topo.server_switches):
+        for i, l in enumerate(self.topo.c2r_router_switches):
-            cmd = self.interface_up_command(self.get_router_interface_to_switch(i),
+            cmd = self.interface_up_command(self.get_router_interface_to_client_switch(i),
                     self.get_router_ip_to_client_switch(i), netmask)
             self.topo.command_to(self.router, cmd)
-            router_interface_mac = self.router.intf(self.get_router_interface_to_switch(i)).MAC()
+            router_interface_mac = self.router.intf(self.get_router_interface_to_client_switch(i)).MAC()
             self.topo.command_to(self.client, "arp -s {} {}".format(
                 self.get_router_ip_to_client_switch(i), router_interface_mac))
 
-        for i in range(int(self.topo.topo_parameter.get(TopoParameter.SERVER_PATHS))):
+        if len(self.topo.r2s_router_switches) == 0:
-            cmd = self.interface_up_command(self.get_router_interface_to_server(i),
+            # Case no server param is specified
+            cmd = self.interface_up_command(self.get_router_interface_to_server_switch(0),
+                    self.get_router_ip_to_server_switch(0), netmask)
+            self.topo.command_to(self.router, cmd)
+            router_interface_mac = self.router.intf(self.get_router_interface_to_server_switch(0)).MAC()
+            self.topo.command_to(self.server, "arp -s {} {}".format(
+                self.get_router_ip_to_server_switch(0), router_interface_mac))
+
+            cmd = self.interface_up_command(self.get_server_interface(0, 0), self.get_server_ip(0), netmask)
+            self.topo.command_to(self.server, cmd)
+            server_interface_mac = self.server.intf(self.get_server_interface(0, 0)).MAC()
+            self.topo.command_to(self.router, "arp -s {} {}".format(
+                self.get_server_ip(0), server_interface_mac))
+
+        for i, l in enumerate(self.topo.r2s_router_switches):
+            cmd = self.interface_up_command(self.get_router_interface_to_server_switch(i),
                     self.get_router_ip_to_server_switch(i), netmask)
             self.topo.command_to(self.router, cmd)
-            router_interface_mac = self.router.intf(self.get_router_interface_to_server(i)).MAC()
+            router_interface_mac = self.router.intf(self.get_router_interface_to_server_switch(i)).MAC()
             self.topo.command_to(self.server, "arp -s {} {}".format(
                 self.get_router_ip_to_server_switch(i), router_interface_mac))
 
-        for i in range(int(self.topo.topo_parameter.get(TopoParameter.SERVER_PATHS))):
+        for i, l in enumerate(self.topo.r2s_server_switches):
             cmd = self.interface_up_command(self.get_server_interface(0, i), self.get_server_ip(i), netmask)
             self.topo.command_to(self.server, cmd)
             server_interface_mac = self.server.intf(self.get_server_interface(0, i)).MAC()
@@ -148,15 +208,18 @@ class MultiInterfaceConfig(TopoConfig):
         return "{}{}.0/24".format(self.param.get(TopoParameter.RIGHT_SUBNET), interface_index)
 
     def client_interface_count(self):
-        return len(self.topo.client_switches)
+        return len(self.topo.c2r_client_switches)
 
-    def get_router_interface_to_server(self, switch_index):
+    def server_interface_count(self):
-        return self.get_router_interface_to_switch(len(self.topo.server_switches) + switch_index)
+        return len(self.topo.r2s_server_switches)
+
+    def get_router_interface_to_server_switch(self, switch_index):
+        return self.get_router_interface_to_client_switch(len(self.topo.c2r_router_switches) + switch_index)
 
     def get_client_interface(self, client_index, interface_index):
         return "{}-eth{}".format(self.topo.get_client_name(client_index), interface_index)
 
-    def get_router_interface_to_switch(self, interface_index):
+    def get_router_interface_to_client_switch(self, interface_index):
         return "{}-eth{}".format(self.topo.get_router_name(0), interface_index)
 
     def get_server_interface(self, server_index, interface_index):

topos/multi_interface_cong.py

@@ -158,10 +158,10 @@ class MultiInterfaceCongConfig(TopoConfig):
             self.topo.command_to(self.router, "arp -s " + self.getCongClientIP(i) + " " + congClientIntfMac)
 
             cmd = self.interface_up_command(
-                    self.get_router_interface_to_switch(i),
+                    self.get_router_interface_to_client_switch(i),
                     self.getRouterIPSwitch(i), netmask)
             self.topo.command_to(self.router, cmd)
-            routerIntfMac = self.router.intf(self.get_router_interface_to_switch(i)).MAC()
+            routerIntfMac = self.router.intf(self.get_router_interface_to_client_switch(i)).MAC()
             self.topo.command_to(self.client, "arp -s " + self.getRouterIPSwitch(i) + " " + routerIntfMac)
             # Don't forget the congestion client
             self.topo.command_to(self.cong_clients[i], "arp -s " + self.getRouterIPSwitch(i) + " " + routerIntfMac)
@@ -240,10 +240,10 @@ class MultiInterfaceCongConfig(TopoConfig):
         return len(self.topo.switch)
 
     def get_router_interface_to_server(self):
-        return self.get_router_interface_to_switch(len(self.topo.switch))
+        return self.get_router_interface_to_client_switch(len(self.topo.switch))
 
     def getRouterInterfaceCongServer(self, congID):
-        return self.get_router_interface_to_switch(len(self.topo.switch) + 1 + congID)
+        return self.get_router_interface_to_client_switch(len(self.topo.switch) + 1 + congID)
 
     def get_client_interface(self, interfaceID):
         return  Topo.CLIENT_NAME + "-eth" + str(interfaceID)
@@ -251,7 +251,7 @@ class MultiInterfaceCongConfig(TopoConfig):
     def getCongClientInterface(self, interfaceID):
         return MultiInterfaceCongConfig.congClientName + str(interfaceID) + "-eth0"
 
-    def get_router_interface_to_switch(self, interfaceID):
+    def get_router_interface_to_client_switch(self, interfaceID):
         return  Topo.ROUTER_NAME + "-eth" + str(interfaceID)
 
     def get_server_interface(self):