+splay_tree_t *subnet_tree;
+
+/* Subnet lookup cache */
+
+static ipv4_t cache_ipv4_address[2];
+static subnet_t *cache_ipv4_subnet[2];
+static bool cache_ipv4_valid[2];
+static int cache_ipv4_slot;
+
+static ipv6_t cache_ipv6_address[2];
+static subnet_t *cache_ipv6_subnet[2];
+static bool cache_ipv6_valid[2];
+static int cache_ipv6_slot;
+
+static mac_t cache_mac_address[2];
+static subnet_t *cache_mac_subnet[2];
+static bool cache_mac_valid[2];
+static int cache_mac_slot;
+
+void subnet_cache_flush() {
+ cache_ipv4_valid[0] = cache_ipv4_valid[1] = false;
+ cache_ipv6_valid[0] = cache_ipv6_valid[1] = false;
+ cache_mac_valid[0] = cache_mac_valid[1] = false;
+}