diff --git a/substrate/core/network/src/custom_proto/behaviour.rs b/substrate/core/network/src/custom_proto/behaviour.rs
index 61fd9c3e7b..babd93f932 100644
--- a/substrate/core/network/src/custom_proto/behaviour.rs
+++ b/substrate/core/network/src/custom_proto/behaviour.rs
@@ -16,13 +16,15 @@
 
 use crate::{DiscoveryNetBehaviour, config::ProtocolId};
 use crate::custom_proto::handler::{CustomProtoHandlerProto, CustomProtoHandlerOut, CustomProtoHandlerIn};
-use crate::custom_proto::upgrade::{CustomMessage, RegisteredProtocol};
+use crate::custom_proto::upgrade::RegisteredProtocol;
+use crate::protocol::message::Message;
 use fnv::FnvHashMap;
 use futures::prelude::*;
 use futures03::{compat::Compat, TryFutureExt as _, StreamExt as _, TryStreamExt as _};
 use libp2p::core::{ConnectedPoint, Multiaddr, PeerId};
 use libp2p::swarm::{NetworkBehaviour, NetworkBehaviourAction, PollParameters};
 use log::{debug, error, trace, warn};
+use runtime_primitives::traits::Block as BlockT;
 use smallvec::SmallVec;
 use std::{borrow::Cow, collections::hash_map::Entry, cmp, error, marker::PhantomData, mem, pin::Pin};
 use std::time::{Duration, Instant};
@@ -58,9 +60,9 @@ use tokio_io::{AsyncRead, AsyncWrite};
 /// Note that this "banning" system is not an actual ban. If a "banned" node tries to connect to
 /// us, we accept the connection. The "banning" system is only about delaying dialing attempts.
 ///
-pub struct CustomProto<TMessage, TSubstream> {
+pub struct CustomProto<B: BlockT, TSubstream> {
 	/// List of protocols to open with peers. Never modified.
-	protocol: RegisteredProtocol<TMessage>,
+	protocol: RegisteredProtocol<B>,
 
 	/// Receiver for instructions about who to connect to or disconnect from.
 	peerset: peerset::Peerset,
@@ -77,7 +79,7 @@ pub struct CustomProto<TMessage, TSubstream> {
 	next_incoming_index: peerset::IncomingIndex,
 
 	/// Events to produce from `poll()`.
-	events: SmallVec<[NetworkBehaviourAction<CustomProtoHandlerIn<TMessage>, CustomProtoOut<TMessage>>; 4]>,
+	events: SmallVec<[NetworkBehaviourAction<CustomProtoHandlerIn<B>, CustomProtoOut<B>>; 4]>,
 
 	/// Marker to pin the generics.
 	marker: PhantomData<TSubstream>,
@@ -186,7 +188,7 @@ struct IncomingPeer {
 
 /// Event that can be emitted by the `CustomProto`.
 #[derive(Debug)]
-pub enum CustomProtoOut<TMessage> {
+pub enum CustomProtoOut<B: BlockT> {
 	/// Opened a custom protocol with the remote.
 	CustomProtocolOpen {
 		/// Version of the protocol that has been opened.
@@ -210,7 +212,7 @@ pub enum CustomProtoOut<TMessage> {
 		/// Id of the peer the message came from.
 		peer_id: PeerId,
 		/// Message that has been received.
-		message: TMessage,
+		message: Message<B>,
 	},
 
 	/// The substream used by the protocol is pretty large. We should print avoid sending more
@@ -219,11 +221,11 @@ pub enum CustomProtoOut<TMessage> {
 		/// Id of the peer which is clogged.
 		peer_id: PeerId,
 		/// Copy of the messages that are within the buffer, for further diagnostic.
-		messages: Vec<TMessage>,
+		messages: Vec<Message<B>>,
 	},
 }
 
-impl<TMessage, TSubstream> CustomProto<TMessage, TSubstream> {
+impl<B: BlockT, TSubstream> CustomProto<B, TSubstream> {
 	/// Creates a `CustomProtos`.
 	pub fn new(
 		protocol: impl Into<ProtocolId>,
@@ -347,7 +349,8 @@ impl<TMessage, TSubstream> CustomProto<TMessage, TSubstream> {
 	///
 	/// Also note that even we have a valid open substream, it may in fact be already closed
 	/// without us knowing, in which case the packet will not be received.
-	pub fn send_packet(&mut self, target: &PeerId, message: TMessage) {
+	pub fn send_packet(&mut self, target: &PeerId, message: Message<B>)
+	where B: BlockT {
 		if !self.is_open(target) {
 			return;
 		}
@@ -603,7 +606,7 @@ impl<TMessage, TSubstream> CustomProto<TMessage, TSubstream> {
 	}
 }
 
-impl<TMessage, TSubstream> DiscoveryNetBehaviour for CustomProto<TMessage, TSubstream> {
+impl<B: BlockT, TSubstream> DiscoveryNetBehaviour for CustomProto<B, TSubstream> {
 	fn add_discovered_nodes(&mut self, peer_ids: impl Iterator<Item = PeerId>) {
 		self.peerset.discovered(peer_ids.into_iter().map(|peer_id| {
 			debug!(target: "sub-libp2p", "PSM <= Discovered({:?})", peer_id);
@@ -612,13 +615,13 @@ impl<TMessage, TSubstream> DiscoveryNetBehaviour for CustomProto<TMessage, TSubs
 	}
 }
 
-impl<TMessage, TSubstream> NetworkBehaviour for CustomProto<TMessage, TSubstream>
+impl<B, TSubstream> NetworkBehaviour for CustomProto<B, TSubstream>
 where
 	TSubstream: AsyncRead + AsyncWrite,
-	TMessage: CustomMessage,
+	B: BlockT,
 {
-	type ProtocolsHandler = CustomProtoHandlerProto<TMessage, TSubstream>;
-	type OutEvent = CustomProtoOut<TMessage>;
+	type ProtocolsHandler = CustomProtoHandlerProto<B, TSubstream>;
+	type OutEvent = CustomProtoOut<B>;
 
 	fn new_handler(&mut self) -> Self::ProtocolsHandler {
 		CustomProtoHandlerProto::new(self.protocol.clone())
@@ -816,7 +819,7 @@ where
 	fn inject_node_event(
 		&mut self,
 		source: PeerId,
-		event: CustomProtoHandlerOut<TMessage>,
+		event: CustomProtoHandlerOut<B>,
 	) {
 		match event {
 			CustomProtoHandlerOut::CustomProtocolClosed { reason } => {
@@ -945,7 +948,7 @@ where
 		_params: &mut impl PollParameters,
 	) -> Async<
 		NetworkBehaviourAction<
-			CustomProtoHandlerIn<TMessage>,
+			CustomProtoHandlerIn<B>,
 			Self::OutEvent,
 		>,
 	> {
diff --git a/substrate/core/network/src/custom_proto/handler.rs b/substrate/core/network/src/custom_proto/handler.rs
index 6609998242..6904d18c4b 100644
--- a/substrate/core/network/src/custom_proto/handler.rs
+++ b/substrate/core/network/src/custom_proto/handler.rs
@@ -14,8 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-use crate::custom_proto::upgrade::{CustomMessage, RegisteredProtocol};
-use crate::custom_proto::upgrade::{RegisteredProtocolEvent, RegisteredProtocolSubstream};
+use crate::custom_proto::upgrade::{RegisteredProtocol, RegisteredProtocolEvent, RegisteredProtocolSubstream};
+use crate::protocol::message::Message;
 use futures::prelude::*;
 use futures03::{compat::Compat, TryFutureExt as _};
 use futures_timer::Delay;
@@ -29,6 +29,7 @@ use libp2p::swarm::{
 	SubstreamProtocol,
 };
 use log::{debug, error};
+use runtime_primitives::traits::Block as BlockT;
 use smallvec::{smallvec, SmallVec};
 use std::{borrow::Cow, error, fmt, io, marker::PhantomData, mem, time::Duration};
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -87,21 +88,21 @@ use tokio_io::{AsyncRead, AsyncWrite};
 /// We consider that we are now "closed" if the remote closes all the existing substreams.
 /// Re-opening it can then be performed by closing all active substream and re-opening one.
 ///
-pub struct CustomProtoHandlerProto<TMessage, TSubstream> {
+pub struct CustomProtoHandlerProto<B, TSubstream> {
 	/// Configuration for the protocol upgrade to negotiate.
-	protocol: RegisteredProtocol<TMessage>,
+	protocol: RegisteredProtocol<B>,
 
 	/// Marker to pin the generic type.
 	marker: PhantomData<TSubstream>,
 }
 
-impl<TMessage, TSubstream> CustomProtoHandlerProto<TMessage, TSubstream>
+impl<B, TSubstream> CustomProtoHandlerProto<B, TSubstream>
 where
 	TSubstream: AsyncRead + AsyncWrite,
-	TMessage: CustomMessage,
+	B: BlockT,
 {
 	/// Builds a new `CustomProtoHandlerProto`.
-	pub fn new(protocol: RegisteredProtocol<TMessage>) -> Self {
+	pub fn new(protocol: RegisteredProtocol<B>) -> Self {
 		CustomProtoHandlerProto {
 			protocol,
 			marker: PhantomData,
@@ -109,14 +110,14 @@ where
 	}
 }
 
-impl<TMessage, TSubstream> IntoProtocolsHandler for CustomProtoHandlerProto<TMessage, TSubstream>
+impl<B, TSubstream> IntoProtocolsHandler for CustomProtoHandlerProto<B, TSubstream>
 where
 	TSubstream: AsyncRead + AsyncWrite,
-	TMessage: CustomMessage,
+	B: BlockT,
 {
-	type Handler = CustomProtoHandler<TMessage, TSubstream>;
+	type Handler = CustomProtoHandler<B, TSubstream>;
 
-	fn inbound_protocol(&self) -> RegisteredProtocol<TMessage> {
+	fn inbound_protocol(&self) -> RegisteredProtocol<B> {
 		self.protocol.clone()
 	}
 
@@ -135,12 +136,12 @@ where
 }
 
 /// The actual handler once the connection has been established.
-pub struct CustomProtoHandler<TMessage, TSubstream> {
+pub struct CustomProtoHandler<B: BlockT, TSubstream> {
 	/// Configuration for the protocol upgrade to negotiate.
-	protocol: RegisteredProtocol<TMessage>,
+	protocol: RegisteredProtocol<B>,
 
 	/// State of the communications with the remote.
-	state: ProtocolState<TMessage, TSubstream>,
+	state: ProtocolState<B, TSubstream>,
 
 	/// Identifier of the node we're talking to. Used only for logging purposes and shouldn't have
 	/// any influence on the behaviour.
@@ -154,15 +155,15 @@ pub struct CustomProtoHandler<TMessage, TSubstream> {
 	///
 	/// This queue must only ever be modified to insert elements at the back, or remove the first
 	/// element.
-	events_queue: SmallVec<[ProtocolsHandlerEvent<RegisteredProtocol<TMessage>, (), CustomProtoHandlerOut<TMessage>>; 16]>,
+	events_queue: SmallVec<[ProtocolsHandlerEvent<RegisteredProtocol<B>, (), CustomProtoHandlerOut<B>>; 16]>,
 }
 
 /// State of the handler.
-enum ProtocolState<TMessage, TSubstream> {
+enum ProtocolState<B, TSubstream> {
 	/// Waiting for the behaviour to tell the handler whether it is enabled or disabled.
 	Init {
 		/// List of substreams opened by the remote but that haven't been processed yet.
-		substreams: SmallVec<[RegisteredProtocolSubstream<TMessage, TSubstream>; 6]>,
+		substreams: SmallVec<[RegisteredProtocolSubstream<B, TSubstream>; 6]>,
 		/// Deadline after which the initialization is abnormally long.
 		init_deadline: Compat<Delay>,
 	},
@@ -178,9 +179,9 @@ enum ProtocolState<TMessage, TSubstream> {
 	/// If we are in this state, we have sent a `CustomProtocolOpen` message to the outside.
 	Normal {
 		/// The substreams where bidirectional communications happen.
-		substreams: SmallVec<[RegisteredProtocolSubstream<TMessage, TSubstream>; 4]>,
+		substreams: SmallVec<[RegisteredProtocolSubstream<B, TSubstream>; 4]>,
 		/// Contains substreams which are being shut down.
-		shutdown: SmallVec<[RegisteredProtocolSubstream<TMessage, TSubstream>; 4]>,
+		shutdown: SmallVec<[RegisteredProtocolSubstream<B, TSubstream>; 4]>,
 	},
 
 	/// We are disabled. Contains substreams that are being closed.
@@ -188,7 +189,7 @@ enum ProtocolState<TMessage, TSubstream> {
 	/// outside or we have never sent any `CustomProtocolOpen` in the first place.
 	Disabled {
 		/// List of substreams to shut down.
-		shutdown: SmallVec<[RegisteredProtocolSubstream<TMessage, TSubstream>; 6]>,
+		shutdown: SmallVec<[RegisteredProtocolSubstream<B, TSubstream>; 6]>,
 
 		/// If true, we should reactivate the handler after all the substreams in `shutdown` have
 		/// been closed.
@@ -209,7 +210,7 @@ enum ProtocolState<TMessage, TSubstream> {
 
 /// Event that can be received by a `CustomProtoHandler`.
 #[derive(Debug)]
-pub enum CustomProtoHandlerIn<TMessage> {
+pub enum CustomProtoHandlerIn<B: BlockT> {
 	/// The node should start using custom protocols.
 	Enable,
 
@@ -219,13 +220,13 @@ pub enum CustomProtoHandlerIn<TMessage> {
 	/// Sends a message through a custom protocol substream.
 	SendCustomMessage {
 		/// The message to send.
-		message: TMessage,
+		message: Message<B>,
 	},
 }
 
 /// Event that can be emitted by a `CustomProtoHandler`.
 #[derive(Debug)]
-pub enum CustomProtoHandlerOut<TMessage> {
+pub enum CustomProtoHandlerOut<B: BlockT> {
 	/// Opened a custom protocol with the remote.
 	CustomProtocolOpen {
 		/// Version of the protocol that has been opened.
@@ -241,14 +242,14 @@ pub enum CustomProtoHandlerOut<TMessage> {
 	/// Receives a message on a custom protocol substream.
 	CustomMessage {
 		/// Message that has been received.
-		message: TMessage,
+		message: Message<B>,
 	},
 
 	/// A substream to the remote is clogged. The send buffer is very large, and we should print
 	/// a diagnostic message and/or avoid sending more data.
 	Clogged {
 		/// Copy of the messages that are within the buffer, for further diagnostic.
-		messages: Vec<TMessage>,
+		messages: Vec<Message<B>>,
 	},
 
 	/// An error has happened on the protocol level with this node.
@@ -260,10 +261,10 @@ pub enum CustomProtoHandlerOut<TMessage> {
 	},
 }
 
-impl<TMessage, TSubstream> CustomProtoHandler<TMessage, TSubstream>
+impl<B, TSubstream> CustomProtoHandler<B, TSubstream>
 where
 	TSubstream: AsyncRead + AsyncWrite,
-	TMessage: CustomMessage,
+	B: BlockT,
 {
 	/// Enables the handler.
 	fn enable(&mut self) {
@@ -341,7 +342,7 @@ where
 	/// Polls the state for events. Optionally returns an event to produce.
 	#[must_use]
 	fn poll_state(&mut self)
-		-> Option<ProtocolsHandlerEvent<RegisteredProtocol<TMessage>, (), CustomProtoHandlerOut<TMessage>>> {
+		-> Option<ProtocolsHandlerEvent<RegisteredProtocol<B>, (), CustomProtoHandlerOut<B>>> {
 		match mem::replace(&mut self.state, ProtocolState::Poisoned) {
 			ProtocolState::Poisoned => {
 				error!(target: "sub-libp2p", "Handler with {:?} is in poisoned state",
@@ -470,7 +471,7 @@ where
 	/// Called by `inject_fully_negotiated_inbound` and `inject_fully_negotiated_outbound`.
 	fn inject_fully_negotiated(
 		&mut self,
-		mut substream: RegisteredProtocolSubstream<TMessage, TSubstream>
+		mut substream: RegisteredProtocolSubstream<B, TSubstream>
 	) {
 		self.state = match mem::replace(&mut self.state, ProtocolState::Poisoned) {
 			ProtocolState::Poisoned => {
@@ -515,7 +516,7 @@ where
 	}
 
 	/// Sends a message to the remote.
-	fn send_message(&mut self, message: TMessage) {
+	fn send_message(&mut self, message: Message<B>) {
 		match self.state {
 			ProtocolState::Normal { ref mut substreams, .. } =>
 				substreams[0].send_message(message),
@@ -526,14 +527,14 @@ where
 	}
 }
 
-impl<TMessage, TSubstream> ProtocolsHandler for CustomProtoHandler<TMessage, TSubstream>
-where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
-	type InEvent = CustomProtoHandlerIn<TMessage>;
-	type OutEvent = CustomProtoHandlerOut<TMessage>;
+impl<B, TSubstream> ProtocolsHandler for CustomProtoHandler<B, TSubstream>
+where TSubstream: AsyncRead + AsyncWrite, B: BlockT {
+	type InEvent = CustomProtoHandlerIn<B>;
+	type OutEvent = CustomProtoHandlerOut<B>;
 	type Substream = TSubstream;
 	type Error = ConnectionKillError;
-	type InboundProtocol = RegisteredProtocol<TMessage>;
-	type OutboundProtocol = RegisteredProtocol<TMessage>;
+	type InboundProtocol = RegisteredProtocol<B>;
+	type OutboundProtocol = RegisteredProtocol<B>;
 	type OutboundOpenInfo = ();
 
 	fn listen_protocol(&self) -> SubstreamProtocol<Self::InboundProtocol> {
@@ -555,7 +556,7 @@ where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
 		self.inject_fully_negotiated(proto);
 	}
 
-	fn inject_event(&mut self, message: CustomProtoHandlerIn<TMessage>) {
+	fn inject_event(&mut self, message: CustomProtoHandlerIn<B>) {
 		match message {
 			CustomProtoHandlerIn::Disable => self.disable(),
 			CustomProtoHandlerIn::Enable => self.enable(),
@@ -612,7 +613,7 @@ where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
 	}
 }
 
-impl<TMessage, TSubstream> fmt::Debug for CustomProtoHandler<TMessage, TSubstream>
+impl<B: BlockT, TSubstream> fmt::Debug for CustomProtoHandler<B, TSubstream>
 where
 	TSubstream: AsyncRead + AsyncWrite,
 {
@@ -624,9 +625,9 @@ where
 
 /// Given a list of substreams, tries to shut them down. The substreams that have been successfully
 /// shut down are removed from the list.
-fn shutdown_list<TMessage, TSubstream>
-	(list: &mut SmallVec<impl smallvec::Array<Item = RegisteredProtocolSubstream<TMessage, TSubstream>>>)
-where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
+fn shutdown_list<B, TSubstream>
+	(list: &mut SmallVec<impl smallvec::Array<Item = RegisteredProtocolSubstream<B, TSubstream>>>)
+where TSubstream: AsyncRead + AsyncWrite, B: BlockT {
 	'outer: for n in (0..list.len()).rev() {
 		let mut substream = list.swap_remove(n);
 		loop {
diff --git a/substrate/core/network/src/custom_proto/mod.rs b/substrate/core/network/src/custom_proto/mod.rs
index 22c66c1654..99f4f0183a 100644
--- a/substrate/core/network/src/custom_proto/mod.rs
+++ b/substrate/core/network/src/custom_proto/mod.rs
@@ -15,7 +15,6 @@
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 pub use self::behaviour::{CustomProto, CustomProtoOut};
-pub use self::upgrade::CustomMessage;
 
 mod behaviour;
 mod handler;
diff --git a/substrate/core/network/src/custom_proto/tests.rs b/substrate/core/network/src/custom_proto/tests.rs
index b7e72af898..94456b1a0f 100644
--- a/substrate/core/network/src/custom_proto/tests.rs
+++ b/substrate/core/network/src/custom_proto/tests.rs
@@ -25,15 +25,15 @@ use libp2p::{PeerId, Multiaddr, Transport};
 use rand::seq::SliceRandom;
 use std::{io, time::Duration, time::Instant};
 use test_client::runtime::Block;
-use crate::message::{Message as MessageAlias, generic::Message};
-use crate::custom_proto::{CustomProto, CustomProtoOut, CustomMessage};
+use crate::message::generic::Message;
+use crate::custom_proto::{CustomProto, CustomProtoOut};
 
 /// Builds two nodes that have each other as bootstrap nodes.
 /// This is to be used only for testing, and a panic will happen if something goes wrong.
-fn build_nodes<T: CustomMessage + Send + 'static>()
+fn build_nodes()
 -> (
-	Swarm<Boxed<(PeerId, StreamMuxerBox), io::Error>, CustomProtoWithAddr<T>>,
-	Swarm<Boxed<(PeerId, StreamMuxerBox), io::Error>, CustomProtoWithAddr<T>>
+	Swarm<Boxed<(PeerId, StreamMuxerBox), io::Error>, CustomProtoWithAddr>,
+	Swarm<Boxed<(PeerId, StreamMuxerBox), io::Error>, CustomProtoWithAddr>
 ) {
 	let mut out = Vec::with_capacity(2);
 
@@ -100,29 +100,29 @@ fn build_nodes<T: CustomMessage + Send + 'static>()
 }
 
 /// Wraps around the `CustomBehaviour` network behaviour, and adds hardcoded node addresses to it.
-struct CustomProtoWithAddr<T: CustomMessage + Send + 'static> {
-	inner: CustomProto<T, Substream<StreamMuxerBox>>,
+struct CustomProtoWithAddr {
+	inner: CustomProto<Block, Substream<StreamMuxerBox>>,
 	addrs: Vec<(PeerId, Multiaddr)>,
 }
 
-impl<T: CustomMessage + Send + 'static> std::ops::Deref for CustomProtoWithAddr<T> {
-	type Target = CustomProto<T, Substream<StreamMuxerBox>>;
+impl std::ops::Deref for CustomProtoWithAddr {
+	type Target = CustomProto<Block, Substream<StreamMuxerBox>>;
 
 	fn deref(&self) -> &Self::Target {
 		&self.inner
 	}
 }
 
-impl<T: CustomMessage + Send + 'static> std::ops::DerefMut for CustomProtoWithAddr<T> {
+impl std::ops::DerefMut for CustomProtoWithAddr {
 	fn deref_mut(&mut self) -> &mut Self::Target {
 		&mut self.inner
 	}
 }
 
-impl<T: CustomMessage + Send + 'static> NetworkBehaviour for CustomProtoWithAddr<T> {
+impl NetworkBehaviour for CustomProtoWithAddr {
 	type ProtocolsHandler =
-		<CustomProto<T, Substream<StreamMuxerBox>> as NetworkBehaviour>::ProtocolsHandler;
-	type OutEvent = <CustomProto<T, Substream<StreamMuxerBox>> as NetworkBehaviour>::OutEvent;
+		<CustomProto<Block, Substream<StreamMuxerBox>> as NetworkBehaviour>::ProtocolsHandler;
+	type OutEvent = <CustomProto<Block, Substream<StreamMuxerBox>> as NetworkBehaviour>::OutEvent;
 
 	fn new_handler(&mut self) -> Self::ProtocolsHandler {
 		self.inner.new_handler()
@@ -200,7 +200,7 @@ fn two_nodes_transfer_lots_of_packets() {
 	// substreams allowed by the multiplexer.
 	const NUM_PACKETS: u32 = 5000;
 
-	let (mut service1, mut service2) = build_nodes::<MessageAlias<Block>>();
+	let (mut service1, mut service2) = build_nodes();
 
 	let fut1 = future::poll_fn(move || -> io::Result<_> {
 		loop {
@@ -241,7 +241,7 @@ fn two_nodes_transfer_lots_of_packets() {
 
 #[test]
 fn basic_two_nodes_requests_in_parallel() {
-	let (mut service1, mut service2) = build_nodes::<MessageAlias<Block>>();
+	let (mut service1, mut service2) = build_nodes();
 
 	// Generate random messages with or without a request id.
 	let mut to_send = {
@@ -296,7 +296,7 @@ fn reconnect_after_disconnect() {
 	// We connect two nodes together, then force a disconnect (through the API of the `Service`),
 	// check that the disconnect worked, and finally check whether they successfully reconnect.
 
-	let (mut service1, mut service2) = build_nodes::<MessageAlias<Block>>();
+	let (mut service1, mut service2) = build_nodes();
 
 	// We use the `current_thread` runtime because it doesn't require us to have `'static` futures.
 	let mut runtime = tokio::runtime::current_thread::Runtime::new().unwrap();
diff --git a/substrate/core/network/src/custom_proto/upgrade.rs b/substrate/core/network/src/custom_proto/upgrade.rs
index 4cb6cb5dd9..c01de89cdd 100644
--- a/substrate/core/network/src/custom_proto/upgrade.rs
+++ b/substrate/core/network/src/custom_proto/upgrade.rs
@@ -15,12 +15,15 @@
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 use crate::config::ProtocolId;
+use crate::protocol::message::Message;
 use bytes::Bytes;
 use libp2p::core::{Negotiated, Endpoint, UpgradeInfo, InboundUpgrade, OutboundUpgrade, upgrade::ProtocolName};
 use libp2p::tokio_codec::Framed;
 use log::warn;
 use std::{collections::VecDeque, io, marker::PhantomData, vec::IntoIter as VecIntoIter};
 use futures::{prelude::*, future, stream};
+use parity_codec::{Decode, Encode};
+use runtime_primitives::traits::Block as BlockT;
 use tokio_io::{AsyncRead, AsyncWrite};
 use unsigned_varint::codec::UviBytes;
 
@@ -28,7 +31,7 @@ use unsigned_varint::codec::UviBytes;
 ///
 /// Note that "a single protocol" here refers to `par` for example. However
 /// each protocol can have multiple different versions for networking purposes.
-pub struct RegisteredProtocol<TMessage> {
+pub struct RegisteredProtocol<B> {
 	/// Id of the protocol for API purposes.
 	id: ProtocolId,
 	/// Base name of the protocol as advertised on the network.
@@ -38,10 +41,10 @@ pub struct RegisteredProtocol<TMessage> {
 	/// Ordered in descending order so that the best comes first.
 	supported_versions: Vec<u8>,
 	/// Marker to pin the generic.
-	marker: PhantomData<TMessage>,
+	marker: PhantomData<B>,
 }
 
-impl<TMessage> RegisteredProtocol<TMessage> {
+impl<B> RegisteredProtocol<B> {
 	/// Creates a new `RegisteredProtocol`. The `custom_data` parameter will be
 	/// passed inside the `RegisteredProtocolOutput`.
 	pub fn new(protocol: impl Into<ProtocolId>, versions: &[u8])
@@ -64,7 +67,7 @@ impl<TMessage> RegisteredProtocol<TMessage> {
 	}
 }
 
-impl<TMessage> Clone for RegisteredProtocol<TMessage> {
+impl<B> Clone for RegisteredProtocol<B> {
 	fn clone(&self) -> Self {
 		RegisteredProtocol {
 			id: self.id.clone(),
@@ -76,7 +79,7 @@ impl<TMessage> Clone for RegisteredProtocol<TMessage> {
 }
 
 /// Output of a `RegisteredProtocol` upgrade.
-pub struct RegisteredProtocolSubstream<TMessage, TSubstream> {
+pub struct RegisteredProtocolSubstream<B, TSubstream> {
 	/// If true, we are in the process of closing the sink.
 	is_closing: bool,
 	/// Whether the local node opened this substream (dialer), or we received this substream from
@@ -94,10 +97,10 @@ pub struct RegisteredProtocolSubstream<TMessage, TSubstream> {
 	/// unless the buffer empties then fills itself again.
 	clogged_fuse: bool,
 	/// Marker to pin the generic.
-	marker: PhantomData<TMessage>,
+	marker: PhantomData<B>,
 }
 
-impl<TMessage, TSubstream> RegisteredProtocolSubstream<TMessage, TSubstream> {
+impl<B, TSubstream> RegisteredProtocolSubstream<B, TSubstream> {
 	/// Returns the version of the protocol that was negotiated.
 	pub fn protocol_version(&self) -> u8 {
 		self.protocol_version
@@ -121,43 +124,33 @@ impl<TMessage, TSubstream> RegisteredProtocolSubstream<TMessage, TSubstream> {
 	}
 
 	/// Sends a message to the substream.
-	pub fn send_message(&mut self, data: TMessage)
-	where TMessage: CustomMessage {
+	pub fn send_message(&mut self, data: Message<B>)
+	where B: BlockT {
 		if self.is_closing {
 			return
 		}
 
-		self.send_queue.push_back(data.into_bytes());
+		self.send_queue.push_back(data.encode());
 	}
 }
 
-/// Implemented on messages that can be sent or received on the network.
-pub trait CustomMessage {
-	/// Turns a message into the raw bytes to send over the network.
-	fn into_bytes(self) -> Vec<u8>;
-
-	/// Tries to parse `bytes` received from the network into a message.
-	fn from_bytes(bytes: &[u8]) -> Result<Self, ()>
-		where Self: Sized;
-}
-
 /// Event produced by the `RegisteredProtocolSubstream`.
 #[derive(Debug, Clone)]
-pub enum RegisteredProtocolEvent<TMessage> {
+pub enum RegisteredProtocolEvent<B: BlockT> {
 	/// Received a message from the remote.
-	Message(TMessage),
+	Message(Message<B>),
 
 	/// Diagnostic event indicating that the connection is clogged and we should avoid sending too
 	/// many messages to it.
 	Clogged {
 		/// Copy of the messages that are within the buffer, for further diagnostic.
-		messages: Vec<TMessage>,
+		messages: Vec<Message<B>>,
 	},
 }
 
-impl<TMessage, TSubstream> Stream for RegisteredProtocolSubstream<TMessage, TSubstream>
-where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
-	type Item = RegisteredProtocolEvent<TMessage>;
+impl<B, TSubstream> Stream for RegisteredProtocolSubstream<B, TSubstream>
+where TSubstream: AsyncRead + AsyncWrite, B: BlockT {
+	type Item = RegisteredProtocolEvent<B>;
 	type Error = io::Error;
 
 	fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
@@ -186,7 +179,7 @@ where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
 				self.clogged_fuse = true;
 				return Ok(Async::Ready(Some(RegisteredProtocolEvent::Clogged {
 					messages: self.send_queue.iter()
-						.map(|m| CustomMessage::from_bytes(&m))
+						.map(|m| Decode::decode(&mut &m[..]).ok_or(()))
 						.filter_map(Result::ok)
 						.collect(),
 				})))
@@ -206,7 +199,7 @@ where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
 		// Note that `inner` is wrapped in a `Fuse`, therefore we can poll it forever.
 		match self.inner.poll()? {
 			Async::Ready(Some(data)) => {
-				let message = <TMessage as CustomMessage>::from_bytes(&data)
+				let message = <Message<B> as Decode>::decode(&mut &data[..]).ok_or(())
 					.map_err(|()| {
 						warn!(target: "sub-libp2p", "Couldn't decode packet sent by the remote: {:?}", data);
 						io::ErrorKind::InvalidData
@@ -224,7 +217,7 @@ where TSubstream: AsyncRead + AsyncWrite, TMessage: CustomMessage {
 	}
 }
 
-impl<TMessage> UpgradeInfo for RegisteredProtocol<TMessage> {
+impl<B> UpgradeInfo for RegisteredProtocol<B> {
 	type Info = RegisteredProtocolName;
 	type InfoIter = VecIntoIter<Self::Info>;
 
@@ -259,10 +252,10 @@ impl ProtocolName for RegisteredProtocolName {
 	}
 }
 
-impl<TMessage, TSubstream> InboundUpgrade<TSubstream> for RegisteredProtocol<TMessage>
+impl<B, TSubstream> InboundUpgrade<TSubstream> for RegisteredProtocol<B>
 where TSubstream: AsyncRead + AsyncWrite,
 {
-	type Output = RegisteredProtocolSubstream<TMessage, TSubstream>;
+	type Output = RegisteredProtocolSubstream<B, TSubstream>;
 	type Future = future::FutureResult<Self::Output, io::Error>;
 	type Error = io::Error;
 
@@ -290,7 +283,7 @@ where TSubstream: AsyncRead + AsyncWrite,
 	}
 }
 
-impl<TMessage, TSubstream> OutboundUpgrade<TSubstream> for RegisteredProtocol<TMessage>
+impl<B, TSubstream> OutboundUpgrade<TSubstream> for RegisteredProtocol<B>
 where TSubstream: AsyncRead + AsyncWrite,
 {
 	type Output = <Self as InboundUpgrade<TSubstream>>::Output;
diff --git a/substrate/core/network/src/protocol.rs b/substrate/core/network/src/protocol.rs
index dcb4ea35d0..0d71955474 100644
--- a/substrate/core/network/src/protocol.rs
+++ b/substrate/core/network/src/protocol.rs
@@ -111,7 +111,7 @@ pub struct Protocol<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> {
 	/// When asked for a proof of finality, we use this struct to build one.
 	finality_proof_provider: Option<Arc<dyn FinalityProofProvider<B>>>,
 	/// Handles opening the unique substream and sending and receiving raw messages.
-	behaviour: CustomProto<Message<B>, Substream<StreamMuxerBox>>,
+	behaviour: CustomProto<B, Substream<StreamMuxerBox>>,
 }
 
 /// A peer that we are connected to
@@ -150,7 +150,7 @@ pub struct PeerInfo<B: BlockT> {
 }
 
 struct OnDemandIn<'a, B: BlockT> {
-	behaviour: &'a mut CustomProto<Message<B>, Substream<StreamMuxerBox>>,
+	behaviour: &'a mut CustomProto<B, Substream<StreamMuxerBox>>,
 	peerset: peerset::PeersetHandle,
 }
 
@@ -281,7 +281,7 @@ pub trait Context<B: BlockT> {
 
 /// Protocol context.
 struct ProtocolContext<'a, B: 'a + BlockT, H: 'a + ExHashT> {
-	behaviour: &'a mut CustomProto<Message<B>, Substream<StreamMuxerBox>>,
+	behaviour: &'a mut CustomProto<B, Substream<StreamMuxerBox>>,
 	context_data: &'a mut ContextData<B, H>,
 	peerset_handle: &'a peerset::PeersetHandle,
 }
@@ -289,7 +289,7 @@ struct ProtocolContext<'a, B: 'a + BlockT, H: 'a + ExHashT> {
 impl<'a, B: BlockT + 'a, H: 'a + ExHashT> ProtocolContext<'a, B, H> {
 	fn new(
 		context_data: &'a mut ContextData<B, H>,
-		behaviour: &'a mut CustomProto<Message<B>, Substream<StreamMuxerBox>>,
+		behaviour: &'a mut CustomProto<B, Substream<StreamMuxerBox>>,
 		peerset_handle: &'a peerset::PeersetHandle,
 	) -> Self {
 		ProtocolContext { context_data, peerset_handle, behaviour }
@@ -1479,7 +1479,7 @@ pub enum CustomMessageOutcome<B: BlockT> {
 }
 
 fn send_message<B: BlockT, H: ExHashT>(
-	behaviour: &mut CustomProto<Message<B>, Substream<StreamMuxerBox>>,
+	behaviour: &mut CustomProto<B, Substream<StreamMuxerBox>>,
 	peers: &mut HashMap<PeerId, Peer<B, H>>,
 	who: PeerId,
 	mut message: Message<B>,
@@ -1500,7 +1500,7 @@ fn send_message<B: BlockT, H: ExHashT>(
 
 impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> NetworkBehaviour for
 Protocol<B, S, H> {
-	type ProtocolsHandler = <CustomProto<Message<B>, Substream<StreamMuxerBox>> as NetworkBehaviour>::ProtocolsHandler;
+	type ProtocolsHandler = <CustomProto<B, Substream<StreamMuxerBox>> as NetworkBehaviour>::ProtocolsHandler;
 	type OutEvent = CustomMessageOutcome<B>;
 
 	fn new_handler(&mut self) -> Self::ProtocolsHandler {
diff --git a/substrate/core/network/src/protocol/message.rs b/substrate/core/network/src/protocol/message.rs
index 7b9b684cd8..5aa47d9c26 100644
--- a/substrate/core/network/src/protocol/message.rs
+++ b/substrate/core/network/src/protocol/message.rs
@@ -125,7 +125,6 @@ pub struct RemoteReadResponse {
 
 /// Generic types.
 pub mod generic {
-	use crate::custom_proto::CustomMessage;
 	use parity_codec::{Encode, Decode};
 	use runtime_primitives::Justification;
 	use crate::config::Roles;
@@ -210,18 +209,6 @@ pub mod generic {
 		ChainSpecific(Vec<u8>),
 	}
 
-	impl<Header, Hash, Number, Extrinsic> CustomMessage for Message<Header, Hash, Number, Extrinsic>
-		where Self: Decode + Encode
-	{
-		fn into_bytes(self) -> Vec<u8> {
-			self.encode()
-		}
-
-		fn from_bytes(bytes: &[u8]) -> Result<Self, ()> {
-			Decode::decode(&mut &bytes[..]).ok_or(())
-		}
-	}
-
 	/// Status sent on connection.
 	#[derive(Debug, PartialEq, Eq, Clone, Encode, Decode)]
 	pub struct Status<Hash, Number> {