diff --git a/network/src/metrics.rs b/network/src/metrics.rs
index 1bc4666df1..8a0b3eb835 100644
--- a/network/src/metrics.rs
+++ b/network/src/metrics.rs
@@ -331,3 +331,63 @@ impl CidFrameCache {
         &self.cache[frame.get_int() as usize]
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        metrics::*,
+        types::{Frame, Pid},
+    };
+
+    #[test]
+    fn register_metrics() {
+        let registry = Registry::new();
+        let metrics = NetworkMetrics::new(&Pid::fake(1)).unwrap();
+        metrics.register(&registry).unwrap();
+    }
+
+    #[test]
+    fn pid_cid_frame_cache() {
+        let pid = Pid::fake(1);
+        let frame1 = Frame::Raw("Foo".as_bytes().to_vec());
+        let frame2 = Frame::Raw("Bar".as_bytes().to_vec());
+        let metrics = NetworkMetrics::new(&pid).unwrap();
+        let mut cache = PidCidFrameCache::new(metrics.frames_in_total, pid);
+        let v1 = cache.with_label_values(1, &frame1);
+        v1.inc();
+        assert_eq!(v1.get(), 1);
+        let v2 = cache.with_label_values(1, &frame1);
+        v2.inc();
+        assert_eq!(v2.get(), 2);
+        let v3 = cache.with_label_values(1, &frame2);
+        v3.inc();
+        assert_eq!(v3.get(), 3);
+        let v4 = cache.with_label_values(3, &frame1);
+        v4.inc();
+        assert_eq!(v4.get(), 1);
+        let v5 = cache.with_label_values(3, &Frame::Shutdown);
+        v5.inc();
+        assert_eq!(v5.get(), 1);
+    }
+
+    #[test]
+    fn cid_frame_cache() {
+        let pid = Pid::fake(1);
+        let frame1 = Frame::Raw("Foo".as_bytes().to_vec());
+        let frame2 = Frame::Raw("Bar".as_bytes().to_vec());
+        let metrics = NetworkMetrics::new(&pid).unwrap();
+        let mut cache = CidFrameCache::new(metrics.frames_wire_out_total, 1);
+        let v1 = cache.with_label_values(&frame1);
+        v1.inc();
+        assert_eq!(v1.get(), 1);
+        let v2 = cache.with_label_values(&frame1);
+        v2.inc();
+        assert_eq!(v2.get(), 2);
+        let v3 = cache.with_label_values(&frame2);
+        v3.inc();
+        assert_eq!(v3.get(), 3);
+        let v4 = cache.with_label_values(&Frame::Shutdown);
+        v4.inc();
+        assert_eq!(v4.get(), 1);
+    }
+}
diff --git a/network/src/protocols.rs b/network/src/protocols.rs
index dbd0f13714..3a96cd380c 100644
--- a/network/src/protocols.rs
+++ b/network/src/protocols.rs
@@ -52,6 +52,7 @@ pub(crate) struct UdpProtocol {
     data_in: RwLock<mpsc::UnboundedReceiver<Vec<u8>>>,
 }
 
+//TODO: PERFORMACE: Use BufWriter and BufReader from std::io!
 impl TcpProtocol {
     pub(crate) fn new(stream: TcpStream, metrics: Arc<NetworkMetrics>) -> Self {
         Self { stream, metrics }
diff --git a/network/src/types.rs b/network/src/types.rs
index d8fc7c568d..88a64ce509 100644
--- a/network/src/types.rs
+++ b/network/src/types.rs
@@ -310,3 +310,34 @@ fn sixlet_to_str(sixlet: u128) -> char {
         _ => '-',
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::types::*;
+
+    #[test]
+    fn frame_int2str() {
+        assert_eq!(Frame::int_to_string(3), "OpenStream");
+        assert_eq!(Frame::int_to_string(7), "Raw");
+        assert_eq!(Frame::int_to_string(8), "");
+    }
+
+    #[test]
+    fn frame_get_int() {
+        assert_eq!(Frame::get_int(&Frame::Raw("Foo".as_bytes().to_vec())), 7);
+        assert_eq!(Frame::get_int(&Frame::Shutdown), 2);
+    }
+
+    #[test]
+    fn frame_creation() {
+        Pid::new();
+        assert_eq!(format!("{}", Pid::fake(2)), "CAAAAA");
+    }
+
+    #[test]
+    fn test_sixlet_to_str() {
+        assert_eq!(sixlet_to_str(0), 'A');
+        assert_eq!(sixlet_to_str(63), '/');
+        assert_eq!(sixlet_to_str(64), '-');
+    }
+}
diff --git a/network/tests/integration.rs b/network/tests/integration.rs
index c9451ebec8..0f0d489560 100644
--- a/network/tests/integration.rs
+++ b/network/tests/integration.rs
@@ -1,8 +1,9 @@
 use async_std::task;
 use task::block_on;
-use veloren_network::StreamError;
+use veloren_network::{NetworkError, StreamError};
 mod helper;
 use helper::{network_participant_stream, tcp, udp};
+use std::io::ErrorKind;
 
 #[test]
 #[ignore]
@@ -157,3 +158,27 @@ fn tcp_and_udp_2_connections() -> std::result::Result<(), Box<dyn std::error::Er
         Ok(())
     })
 }
+
+#[test]
+fn failed_listen_on_used_ports() -> std::result::Result<(), Box<dyn std::error::Error>> {
+    let (_, _) = helper::setup(false, 0);
+    let network = Network::new(Pid::new(), &ThreadPoolBuilder::new().build(), None);
+    let udp1 = udp();
+    let tcp1 = tcp();
+    block_on(network.listen(udp1.clone()))?;
+    block_on(network.listen(tcp1.clone()))?;
+    std::thread::sleep(std::time::Duration::from_millis(50));
+
+    let network2 = Network::new(Pid::new(), &ThreadPoolBuilder::new().build(), None);
+    let e1 = block_on(network2.listen(udp1));
+    let e2 = block_on(network2.listen(tcp1));
+    match e1 {
+        Err(NetworkError::ListenFailed(e)) if e.kind() == ErrorKind::AddrInUse => (),
+        _ => assert!(false),
+    };
+    match e2 {
+        Err(NetworkError::ListenFailed(e)) if e.kind() == ErrorKind::AddrInUse => (),
+        _ => assert!(false),
+    };
+    Ok(())
+}