diff --git a/src/ethcloud.rs b/src/ethcloud.rs
index 620faf7..7488d7b 100644
--- a/src/ethcloud.rs
+++ b/src/ethcloud.rs
@@ -11,7 +11,7 @@ use epoll;
 
 use super::{ethernet, udpmessage};
 use super::udpmessage::{Options, Message};
-use super::ethernet::VlanId;
+use super::ethernet::MacTable;
 use super::tapdev::TapDevice;
 
 
@@ -104,60 +104,6 @@ impl PeerList {
 }
 
 
-#[derive(Clone, Copy, PartialEq, Eq, Hash)]
-struct MacTableKey {
-    mac: Mac,
-    vlan: VlanId
-}
-
-struct MacTableValue {
-    address: SocketAddr,
-    timeout: SteadyTime
-}
-
-struct MacTable {
-    table: HashMap<MacTableKey, MacTableValue>,
-    timeout: Duration
-}
-
-impl MacTable {
-    fn new(timeout: Duration) -> MacTable {
-        MacTable{table: HashMap::new(), timeout: timeout}
-    }
-
-    fn timeout(&mut self) {
-        let now = SteadyTime::now();
-        let mut del: Vec<MacTableKey> = Vec::new();
-        for (&key, val) in &self.table {
-            if val.timeout < now {
-                del.push(key);
-            }
-        }
-        for key in del {
-            info!("Forgot mac: {:?} (vlan {})", key.mac, key.vlan);
-            self.table.remove(&key);
-        }
-    }
-
-    #[inline]
-    fn learn(&mut self, mac: &Mac, vlan: VlanId, addr: &SocketAddr) {
-       let key = MacTableKey{mac: *mac, vlan: vlan};
-       let value = MacTableValue{address: *addr, timeout: SteadyTime::now()+self.timeout};
-       if self.table.insert(key, value).is_none() {
-           info!("Learned mac: {:?} (vlan {}) => {}", mac, vlan, addr);
-       }
-    }
-
-    #[inline]
-    fn lookup(&self, mac: &Mac, vlan: VlanId) -> Option<SocketAddr> {
-       let key = MacTableKey{mac: *mac, vlan: vlan};
-       match self.table.get(&key) {
-           Some(value) => Some(value.address),
-           None => None
-       }
-    }
-}
-
 pub struct EthCloud {
     peers: PeerList,
     reconnect_peers: Vec<SocketAddr>,
diff --git a/src/ethernet.rs b/src/ethernet.rs
index 018f686..2660184 100644
--- a/src/ethernet.rs
+++ b/src/ethernet.rs
@@ -1,8 +1,13 @@
 use std::{mem, ptr, fmt};
+use std::net::SocketAddr;
+use std::collections::HashMap;
 
 use super::ethcloud::{Mac, Error};
 use super::util::{as_bytes, as_obj};
 
+use time::{Duration, SteadyTime};
+
+
 pub type VlanId = u16;
 
 #[derive(PartialEq)]
@@ -67,6 +72,61 @@ pub fn encode(frame: &Frame, buf: &mut [u8]) -> usize {
 }
 
 
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+struct MacTableKey {
+    mac: Mac,
+    vlan: VlanId
+}
+
+struct MacTableValue {
+    address: SocketAddr,
+    timeout: SteadyTime
+}
+
+pub struct MacTable {
+    table: HashMap<MacTableKey, MacTableValue>,
+    timeout: Duration
+}
+
+impl MacTable {
+    pub fn new(timeout: Duration) -> MacTable {
+        MacTable{table: HashMap::new(), timeout: timeout}
+    }
+
+    pub fn timeout(&mut self) {
+        let now = SteadyTime::now();
+        let mut del: Vec<MacTableKey> = Vec::new();
+        for (&key, val) in &self.table {
+            if val.timeout < now {
+                del.push(key);
+            }
+        }
+        for key in del {
+            info!("Forgot mac: {:?} (vlan {})", key.mac, key.vlan);
+            self.table.remove(&key);
+        }
+    }
+
+    #[inline]
+    pub fn learn(&mut self, mac: &Mac, vlan: VlanId, addr: &SocketAddr) {
+       let key = MacTableKey{mac: *mac, vlan: vlan};
+       let value = MacTableValue{address: *addr, timeout: SteadyTime::now()+self.timeout};
+       if self.table.insert(key, value).is_none() {
+           info!("Learned mac: {:?} (vlan {}) => {}", mac, vlan, addr);
+       }
+    }
+
+    #[inline]
+    pub fn lookup(&self, mac: &Mac, vlan: VlanId) -> Option<SocketAddr> {
+       let key = MacTableKey{mac: *mac, vlan: vlan};
+       match self.table.get(&key) {
+           Some(value) => Some(value.address),
+           None => None
+       }
+    }
+}
+
+
 #[test]
 fn without_vlan() {
     let src = Mac([1,2,3,4,5,6]);
diff --git a/src/ip.rs b/src/ip.rs
new file mode 100644
index 0000000..82b464e
--- /dev/null
+++ b/src/ip.rs
@@ -0,0 +1,53 @@
+use std::net::SocketAddr;
+use std::collections::{hash_map, HashMap};
+
+struct RoutingEntry {
+    address: SocketAddr,
+    bytes: Vec<u8>,
+    prefix_len: u8
+}
+
+pub struct RoutingTable(HashMap<Vec<u8>, Vec<RoutingEntry>>);
+
+impl RoutingTable {
+    pub fn new() -> Self {
+        RoutingTable(HashMap::new())
+    }
+
+    pub fn add(&mut self, bytes: Vec<u8>, prefix_len: u8, address: SocketAddr) {
+        let group_len = (prefix_len as usize / 16) * 2;
+        let group_bytes: Vec<u8> = bytes[..group_len].iter().map(|b| *b).collect();
+        let routing_entry = RoutingEntry{address: address, bytes: bytes, prefix_len: prefix_len};
+        match self.0.entry(group_bytes) {
+            hash_map::Entry::Occupied(mut entry) => entry.get_mut().push(routing_entry),
+            hash_map::Entry::Vacant(entry) => { entry.insert(vec![routing_entry]); () }
+        }
+    }
+
+    pub fn lookup(&self, bytes: Vec<u8>) -> Option<SocketAddr> {
+        let mut len = bytes.len()/2 * 2;
+        for i in 0..len/2 {
+            if let Some(group) = self.0.get(&bytes[0..len-2*i]) {
+                for entry in group {
+                    if entry.bytes.len() != bytes.len() {
+                        continue;
+                    }
+                    let mut match_len = 0;
+                    for i in 0..bytes.len() {
+                        let b = bytes[i] ^ entry.bytes[i];
+                        if b == 0 {
+                            match_len += 8;
+                        } else {
+                            match_len += b.leading_zeros();
+                            break;
+                        }
+                    }
+                    if match_len as u8 >= entry.prefix_len {
+                        return Some(entry.address);
+                    }
+                }
+            }
+        }
+        None
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index bab77cf..d23403f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,6 +8,7 @@ mod util;
 mod udpmessage;
 mod tapdev;
 mod ethernet;
+mod ip;
 mod ethcloud;
 
 use time::Duration;