diff --git a/_modules/routers.py b/_modules/routers.py
new file mode 100644
index 0000000..dd70414
--- /dev/null
+++ b/_modules/routers.py
@@ -0,0 +1,119 @@
+import netaddr
+import itertools
+
+
+class Route(object):
+    def __init__(self, interface, router, cidr, next_hop):
+        self.interface = interface
+        self.router = router
+        self.cidr = cidr
+        self.next_hop = next_hop
+
+    def __str__(self):
+        return "%s via %s dev %s src %s # router: %s" % (
+            self.cidr,
+            self.next_hop,
+            self.interface.name,
+            self.interface.cidr.ip,
+            self.router.name)
+
+
+class Interface(object):
+    def __init__(self, name, cidr):
+        self.name = name
+        self.cidr = cidr
+
+    def __str__(self):
+        return self.name
+
+    @staticmethod
+    def from_dict(data, default_name=None):
+        try:
+            cidr = netaddr.IPNetwork("%(address)s/%(netmask)s" % data)
+        except KeyError:
+            cidr = None
+        return Interface(
+            name = data.get('name', default_name),
+            cidr = cidr)
+
+
+class Router(object):
+    def __init__(self,
+                 name,
+                 addresses=None,
+                 networks=None,
+                 implicit_routes=True):
+        self.name = name
+        self.addresses = list(addresses or [])
+        self.networks = list(networks or [])
+        if implicit_routes:
+            self.networks.extend(addr.cidr for addr in self.addresses)
+
+        if any(addr.ip == addr.network for addr in self.addresses):
+            raise ValueError("Invalid router address")
+        if any(cidr.ip != cidr.network for cidr in self.networks):
+            raise ValueError("Invalid destination CIDR")
+
+    def __str__(self):
+        return self.name
+
+    @staticmethod
+    def from_dict(data, default_name=None):
+        options = data.get('options', {})
+        return Router(
+            name = data.get('name', default_name),
+            addresses = [
+                netaddr.IPNetwork(router_addr)
+                for router_addr in data.get('addresses', [])
+            ],
+            networks = [
+                netaddr.IPNetwork(dest_cidr).cidr
+                for dest_cidr in data.get('networks', [])
+            ],
+            implicit_routes = options.get('implicit_routes', True)
+        )
+
+    def get_routes(self, interface):
+        next_hops = [addr.ip for addr in self.addresses
+                     if addr.ip in interface.cidr]
+
+        return [
+            Route(interface, self, dest_cidr, next_hop)
+            for next_hop in next_hops
+            for dest_cidr in self.networks if next_hop not in dest_cidr
+        ]
+
+
+def get_routes(interfaces, routers):
+    def sort_key_cidr(route):
+        return route.cidr.sort_key()
+
+    def sort_key_ifname(route):
+        return (route.interface.name, route.cidr.sort_key())
+
+    interfaces = [Interface.from_dict(data, key)
+                  for key, data in interfaces.items()]
+    routers = [Router.from_dict(data, key)
+               for key, data in routers.items()]
+    routes = [route
+              for interface in interfaces if interface.cidr
+              for router in routers
+              for route in router.get_routes(interface)]
+
+    routes_by_cidr = {k: list(g) for k, g in itertools.groupby(
+        sorted(routes, key=sort_key_cidr),
+        lambda route: route.cidr)
+    }
+
+    for cidr, duplicates in routes_by_cidr.items():
+        if len(duplicates) > 1:
+            raise ValueError("Found multiple routes for %s: %s" % (cidr,
+                ["[via %s dev %s]" % (route.next_hop, route.interface)
+                 for route in duplicates]))
+
+    routes_by_ifname = {k: list(g) for k, g in itertools.groupby(
+        sorted(routes, key=sort_key_ifname),
+        lambda route: route.interface.name)
+    }
+
+    return routes_by_ifname