Disable Mplex by default (#9365)

Co-Authored-By: João Oliveira <hello@jxs.pt>

beacon_node/lighthouse_network/src/config.rs

@@ -125,6 +125,9 @@ pub struct Config {
     /// Whether light client protocols should be enabled.
     pub enable_light_client_server: bool,
 
+    /// Whether to enable the deprecated mplex multiplexer alongside yamux.
+    pub enable_mplex: bool,
+
     /// Configuration for the outbound rate limiter (requests made by this node).
     pub outbound_rate_limiter_config: Option<OutboundRateLimiterConfig>,
 
@@ -362,6 +365,7 @@ impl Default for Config {
             proposer_only: false,
             metrics_enabled: false,
             enable_light_client_server: true,
+            enable_mplex: false,
             outbound_rate_limiter_config: None,
             invalid_block_storage: None,
             inbound_rate_limiter_config: None,

beacon_node/lighthouse_network/src/service/mod.rs

@@ -466,9 +466,13 @@ impl<E: EthSpec> Network<E> {
             }
         };
 
-        // Set up the transport - tcp/quic with noise and mplex
-        let transport = build_transport(local_keypair.clone(), !config.disable_quic_support)
-            .map_err(|e| format!("Failed to build transport: {:?}", e))?;
+        // Set up the transport - tcp/quic with noise and yamux (mplex optional)
+        let transport = build_transport(
+            local_keypair.clone(),
+            !config.disable_quic_support,
+            config.enable_mplex,
+        )
+        .map_err(|e| format!("Failed to build transport: {:?}", e))?;
 
         // use the executor for libp2p
         struct Executor(task_executor::TaskExecutor);

beacon_node/lighthouse_network/src/service/utils.rs

@@ -34,27 +34,39 @@ pub struct Context<'a> {
 type BoxedTransport = Boxed<(PeerId, StreamMuxerBox)>;
 
 /// The implementation supports TCP/IP, QUIC (experimental) over UDP, noise as the encryption layer, and
-/// mplex/yamux as the multiplexing layer (when using TCP).
+/// yamux as the multiplexing layer (when using TCP). Mplex can be optionally enabled.
 pub fn build_transport(
     local_private_key: Keypair,
     quic_support: bool,
+    enable_mplex: bool,
 ) -> std::io::Result<BoxedTransport> {
-    // mplex config
-    let mut mplex_config = libp2p_mplex::Config::new();
-    mplex_config.set_max_buffer_size(256);
-    mplex_config.set_max_buffer_behaviour(libp2p_mplex::MaxBufferBehaviour::Block);
-
     // yamux config
     let yamux_config = yamux::Config::default();
+
     // Creates the TCP transport layer
-    let tcp = libp2p::tcp::tokio::Transport::new(libp2p::tcp::Config::default().nodelay(true))
-        .upgrade(core::upgrade::Version::V1)
-        .authenticate(generate_noise_config(&local_private_key))
-        .multiplex(core::upgrade::SelectUpgrade::new(
-            yamux_config,
-            mplex_config,
-        ))
-        .timeout(Duration::from_secs(10));
+    let tcp: BoxedTransport = if enable_mplex {
+        // Enable both yamux and mplex.
+        let mut mplex_config = libp2p_mplex::Config::new();
+        mplex_config.set_max_num_streams(32);
+        mplex_config.set_max_buffer_behaviour(libp2p_mplex::MaxBufferBehaviour::ResetStream);
+        libp2p::tcp::tokio::Transport::new(libp2p::tcp::Config::default().nodelay(true))
+            .upgrade(core::upgrade::Version::V1)
+            .authenticate(generate_noise_config(&local_private_key))
+            .multiplex(core::upgrade::SelectUpgrade::new(
+                yamux_config,
+                mplex_config,
+            ))
+            .timeout(Duration::from_secs(10))
+            .boxed()
+    } else {
+        // Yamux only
+        libp2p::tcp::tokio::Transport::new(libp2p::tcp::Config::default().nodelay(true))
+            .upgrade(core::upgrade::Version::V1)
+            .authenticate(generate_noise_config(&local_private_key))
+            .multiplex(yamux_config)
+            .timeout(Duration::from_secs(10))
+            .boxed()
+    };
     let transport = if quic_support {
         // Enables Quic
         // The default quic configuration suits us for now.

beacon_node/src/cli.rs

@@ -387,6 +387,14 @@ pub fn cli_app() -> Command {
                 .help("Disables the quic transport. The node will rely solely on the TCP transport for libp2p connections.")
                 .display_order(0)
         )
+        .arg(
+            Arg::new("enable-mplex")
+                .long("enable-mplex")
+                .action(ArgAction::SetTrue)
+                .help_heading(FLAG_HEADER)
+                .help("Enables mplex multiplexer alongside yamux. Yamux is preferred when both are available.")
+                .display_order(0)
+        )
         .arg(
             Arg::new("disable-peer-scoring")
                 .long("disable-peer-scoring")

beacon_node/src/config.rs

@@ -1443,6 +1443,10 @@ pub fn set_network_config(
         config.disable_quic_support = true;
     }
 
+    if parse_flag(cli_args, "enable-mplex") {
+        config.enable_mplex = true;
+    }
+
     if parse_flag(cli_args, "disable-upnp") {
         config.upnp_enabled = false;
     }

book/src/help_bn.md

@@ -494,6 +494,9 @@ Flags:
           Sets the local ENR IP address and port to match those set for
           lighthouse. Specifically, the IP address will be the value of
           --listen-address and the UDP port will be --discovery-port.
+      --enable-mplex
+          Enables mplex multiplexer alongside yamux. Yamux is preferred when
+          both are available.
       --enable-partial-columns
           Enable partial messages for data columns. This can reduce the amount
           of data sent over the network. Enabled by default on Hoodi and