grandpa: update notif protocol name

client/finality-grandpa/src/communication/mod.rs

@@ -69,7 +69,9 @@ pub(crate) mod tests;
 
 /// Name of the notifications protocol used by Grandpa. Must be registered towards the networking
 /// in order for Grandpa to properly function.
-pub const GRANDPA_PROTOCOL_NAME: &'static str = "/paritytech/grandpa/1";
+pub(crate) const GRANDPA_PROTOCOL_NAME: &'static str = "/substrate/grandpa/1";
+/// Old name for the notifications protocol, still used for backward compatibility.
+pub(crate) const GRANDPA_PROTOCOL_LEGACY: &'static str = "/paritytech/grandpa/1";
 
 // cost scalars for reporting peers.
 mod cost {

client/finality-grandpa/src/lib.rs

@@ -717,7 +717,7 @@ pub struct GrandpaParams<Block: BlockT, C, N, SC, VR> {
 pub fn grandpa_peers_set_config() -> sc_network::config::NonDefaultSetConfig {
 	sc_network::config::NonDefaultSetConfig {
 		notifications_protocol: communication::GRANDPA_PROTOCOL_NAME.into(),
-		fallback_names: Vec::new(),
+		fallback_names: vec![communication::GRANDPA_PROTOCOL_LEGACY.into()],
 		// Notifications reach ~256kiB in size at the time of writing on Kusama and Polkadot.
 		max_notification_size: 1024 * 1024,
 		set_config: sc_network::config::SetConfig {