diff --git a/src/lib.rs b/src/lib.rs
index a93251b..23b6c0d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,96 @@
-#[test]
-fn it_works() {
+#![feature(ip_addr)]
+
+use std::fmt;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+
+// A network
+#[derive(Debug)]
+pub enum IpNetwork {
+    V4(Ipv4Network),
+    V6(Ipv6Network),
+}
+
+pub struct Ipv4Network {
+    addr: Ipv4Addr,
+    prefix: u8,
+}
+
+pub struct Ipv6Network {
+    addr: Ipv6Addr,
+    prefix: u8,
+}
+
+impl Ipv4Network {
+    fn new(addr: Ipv4Addr, prefix: u8) -> Ipv4Network {
+        Ipv4Network { addr: addr, prefix: prefix }
+    }
+
+    fn ip(&self) -> &Ipv4Addr {
+        &(self.addr)
+    }
+
+    fn prefix(&self) -> u8 {
+        self.prefix
+    }
+}
+
+impl Ipv6Network {
+    fn new(addr: Ipv6Addr, prefix: u8) -> Ipv6Network {
+        Ipv6Network { addr: addr, prefix: prefix }
+    }
+
+    fn ip(&self) -> &Ipv6Addr {
+        &(self.addr)
+    }
+
+    fn prefix(&self) -> u8 {
+        self.prefix
+    }
+}
+
+impl IpNetwork {
+    pub fn new(ip: IpAddr, prefix: u8) -> IpNetwork {
+        match ip {
+            IpAddr::V4(a) => IpNetwork::V4(Ipv4Network::new(a, prefix)),
+            IpAddr::V6(a) => IpNetwork::V6(Ipv6Network::new(a, prefix)),
+        }
+    }
+    
+    pub fn ip(&self) -> IpAddr {
+        match *self {
+            IpNetwork::V4(ref a) => IpAddr::V4(*a.ip()),
+            IpNetwork::V6(ref a) => IpAddr::V6(*a.ip()),
+        }
+    }
+
+    pub fn prefix(&self) -> u8 {
+        match *self {
+            IpNetwork::V4(ref a) => a.prefix(),
+            IpNetwork::V6(ref a) => a.prefix(),
+        }
+    }
+}
+
+impl fmt::Debug for Ipv4Network {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{}/{}", self.ip(), self.prefix())
+    }
+}
+
+impl fmt::Debug for Ipv6Network {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{}/{}", self.ip(), self.prefix())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::net::Ipv4Addr;
+    use super::*;
+
+    #[test]
+    fn test_create_v4() {
+        let cidr = Ipv4Network::new(Ipv4Addr::new(77, 88, 21, 11), 24);
+        assert_eq!(cidr.prefix(), 24);
+    }
 }