diff --git a/tests/test_rr_graph_huge.py b/tests/test_rr_graph_huge.py
new file mode 100644
index 0000000..72b1aed
--- /dev/null
+++ b/tests/test_rr_graph_huge.py
@@ -0,0 +1,15 @@
+#!/usr/bin/env python3
+
+import sys
+
+sys.path.insert(0, ".")
+
+assert sys.argv[1]
+exec("from vprgen.rr_graph import %s as rr_graph" % (sys.argv[1],))
+
+d = rr_graph.ArchitectureDelegate()
+
+for i in range(0, int(10000000)):
+    d.add_edge(i, i+1, 0, {})
+
+
diff --git a/vprgen/rr_graph/abc.py b/vprgen/rr_graph/abc.py
new file mode 100644
index 0000000..88de31e
--- /dev/null
+++ b/vprgen/rr_graph/abc.py
@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+
+import abc
+from typing import Any, Dict, Iterable, Union
+
+
+class Edge(abc.ABC):
+    @property
+    @abc.abstractmethod
+    def src_node(self) -> int:
+        raise NotImplemented
+
+    @property
+    @abc.abstractmethod
+    def sink_node(self) -> int:
+        raise NotImplemented
+
+    @property
+    @abc.abstractmethod
+    def switch_id(self) -> int:
+        raise NotImplemented
+
+    @property
+    @abc.abstractmethod
+    def metadata(self) -> Union[Dict[str, Any], None]:
+        """Metadata for edge."""
+        raise NotImplemented
+
+
+class Node(abc.ABC):
+    pass
+
+
+class ArchitectureDelegate(abc.ABC):
+    @abc.abstractmethod
+    def edges(self) -> Iterable[Edge]:
+        raise NotImplemented
+
diff --git a/vprgen/rr_graph/basic.py b/vprgen/rr_graph/basic.py
new file mode 100644
index 0000000..e3d58ea
--- /dev/null
+++ b/vprgen/rr_graph/basic.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+
+from collections import namedtuple
+
+from .abc import Edge as EdgeABC
+from .abc import ArchitectureDelegate as ArchitectureDelegateABC
+
+# Implementation using namedtuple
+Edge = namedtuple('Edge', ['src_node', 'sink_node', 'switch_id', 'metadata'])
+EdgeABC.register(Edge)
+
+
+class ArchitectureDelegate:
+    def __init__(self):
+        self.edges = []
+
+    def add_edge(self, src_node, sink_node, switch_id, metadata={}):
+        self.edges.append(Edge(src_node, sink_node, switch_id, metadata))
+
+    def edges(self):
+        return self.edges
+
+
+ArchitectureDelegateABC.register(ArchitectureDelegate)
diff --git a/vprgen/rr_graph/ctypes.py b/vprgen/rr_graph/ctypes.py
new file mode 100644
index 0000000..283d56e
--- /dev/null
+++ b/vprgen/rr_graph/ctypes.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+
+from ctypes import *
+
+from .abc import Edge as EdgeABC
+from .abc import ArchitectureDelegate as ArchitectureDelegateABC
+
+
+"""Implementation using ctypes."""
+
+class Edge(Structure):
+    _fields_ = [
+        ("src_node", c_ulonglong),
+        ("sink_node", c_ulonglong),
+        ("switch_id", c_int),
+        ("metadata", py_object),
+    ]
+
+
+def array_resize(a, new_size):
+    assert new_size > a._length_, (new_size, a._length_)
+    resize(a, sizeof(a._type_)*new_size)
+    return (a._type_*new_size).from_address(addressof(a))
+
+
+class ArchitectureDelegate:
+    def __init__(self):
+        self.i = 0
+        self.s = sizeof(Edge)
+
+        self.edges_l = 10
+        self.edges_mem_owner = (Edge * 10)()
+        self.edges = self.edges_mem_owner
+
+    def add_edge(self, src_node, sink_node, switch_id, metadata={}):
+        if self.i == self.edges_l:
+            print("Doubling edges size", self.edges_l, "->", self.edges_l*2)
+            self.edges_l *= 2
+            self.edges = array_resize(self.edges_mem_owner, self.edges_l)
+        e = self.edges[self.i]
+        e.src_node = src_node
+        e.sink_node = sink_node
+        e.switch_id = switch_id
+        e.metadata = metadata
+        self.i += 1
+
+    def edges(self):
+        return self.edges[:self.i]
+
+
+ArchitectureDelegateABC.register(ArchitectureDelegate)
diff --git a/vprgen/rr_graph/numpy.py b/vprgen/rr_graph/numpy.py
new file mode 100644
index 0000000..fe20197
--- /dev/null
+++ b/vprgen/rr_graph/numpy.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+
+import numpy as np
+
+from .abc import Edge as EdgeABC
+from .abc import ArchitectureDelegate as ArchitectureDelegateABC
+
+"""Implementation using numpy."""
+
+Edge = np.dtype([
+  ('src_node', '=i8'),  # 64bit int
+  ('sink_node', '=i8'), # 64bit int
+  ('switch_id', '=i2'), # 16bit int
+  ('metadata',  'O'),   # dict {}
+])
+
+#EdgeABC.register(Edge)
+
+
+class ArchitectureDelegate:
+    def __init__(self, hint=10485760):
+        self.i = 0
+        self.edges_mem_owner = np.zeros(hint, dtype=Edge)
+        self.edges = self.edges_mem_owner.view(np.recarray)
+
+    def add_edge(self, src_node, sink_node, switch_id, metadata={}):
+        l = len(self.edges)
+        if self.i == l:
+            print("Doubling edges size", l, "->", l*2)
+            del self.edges
+            self.edges_mem_owner.resize(l*2)
+            self.edges = self.edges_mem_owner.view(np.recarray)
+
+        e = self.edges[self.i]
+        e.src_node = src_node
+        e.sink_node = sink_node
+        e.switch_id = switch_id
+        e.metadata = metadata
+        self.i += 1
+
+    def edges(self):
+        return self.edges[:self.i]
+
+
+ArchitectureDelegateABC.register(ArchitectureDelegate)