Gossipsub scoring improvements (sigp#2391)

* Tweak gossipsub parameters for improved scoring

* Modify gossip history

* Update settings

* Make mesh window constant

* Decrease the mesh message deliveries weight

* Fmt

beacon_node/eth2_libp2p/src/behaviour/gossipsub_scoring_parameters.rs

@@ -17,6 +17,23 @@ const VOLUNTARY_EXIT_WEIGHT: f64 = 0.05;
 const PROPOSER_SLASHING_WEIGHT: f64 = 0.05;
 const ATTESTER_SLASHING_WEIGHT: f64 = 0.05;
 
+/// The time window (seconds) that we expect messages to be forwarded to us in the mesh.
+const MESH_MESSAGE_DELIVERIES_WINDOW: u64 = 2;
+
+// Const as this is used in the peer manager to prevent gossip from disconnecting peers.
+pub const GREYLIST_THRESHOLD: f64 = -16000.0;
+
+/// Builds the peer score thresholds.
+pub fn lighthouse_gossip_thresholds() -> PeerScoreThresholds {
+    PeerScoreThresholds {
+        gossip_threshold: -4000.0,
+        publish_threshold: -8000.0,
+        graylist_threshold: GREYLIST_THRESHOLD,
+        accept_px_threshold: 100.0,
+        opportunistic_graft_threshold: 5.0,
+    }
+}
+
 pub struct PeerScoreSettings<TSpec: EthSpec> {
     slot: Duration,
     epoch: Duration,
@@ -75,7 +92,7 @@ impl<TSpec: EthSpec> PeerScoreSettings<TSpec> {
             decay_to_zero: self.decay_to_zero,
             retain_score: self.epoch * 100,
             app_specific_weight: 1.0,
-            ip_colocation_factor_threshold: 3.0,
+            ip_colocation_factor_threshold: 8.0, // Allow up to 8 nodes per IP
             behaviour_penalty_threshold: 6.0,
             behaviour_penalty_decay: self.score_parameter_decay(self.epoch * 10),
             ..Default::default()
@@ -313,10 +330,10 @@ impl<TSpec: EthSpec> PeerScoreSettings<TSpec> {
                     cap_factor * t_params.mesh_message_deliveries_threshold
                 };
             t_params.mesh_message_deliveries_activation = activation_window;
-            t_params.mesh_message_deliveries_window = Duration::from_secs(2);
+            t_params.mesh_message_deliveries_window =
+                Duration::from_secs(MESH_MESSAGE_DELIVERIES_WINDOW);
             t_params.mesh_failure_penalty_decay = t_params.mesh_message_deliveries_decay;
-            t_params.mesh_message_deliveries_weight = -self.max_positive_score
-                / (t_params.topic_weight * t_params.mesh_message_deliveries_threshold.powi(2));
+            t_params.mesh_message_deliveries_weight = -t_params.topic_weight;
             t_params.mesh_failure_penalty_weight = t_params.mesh_message_deliveries_weight;
             if decay_slots >= current_slot.as_u64() {
                 t_params.mesh_message_deliveries_threshold = 0.0;

beacon_node/eth2_libp2p/src/behaviour/mod.rs

@@ -1,4 +1,6 @@
-use crate::behaviour::gossipsub_scoring_parameters::PeerScoreSettings;
+use crate::behaviour::gossipsub_scoring_parameters::{
+    lighthouse_gossip_thresholds, PeerScoreSettings,
+};
 use crate::discovery::{subnet_predicate, Discovery, DiscoveryEvent, TARGET_SUBNET_PEERS};
 use crate::peer_manager::{
     score::ReportSource, ConnectionDirection, PeerManager, PeerManagerEvent,
@@ -19,7 +21,7 @@ use libp2p::{
     gossipsub::{
         subscription_filter::{MaxCountSubscriptionFilter, WhitelistSubscriptionFilter},
         Gossipsub as BaseGossipsub, GossipsubEvent, IdentTopic as Topic, MessageAcceptance,
-        MessageAuthenticity, MessageId, PeerScoreThresholds,
+        MessageAuthenticity, MessageId,
     },
     identify::{Identify, IdentifyConfig, IdentifyEvent},
     swarm::{
@@ -42,10 +44,9 @@ use std::{
 };
 use types::{ChainSpec, EnrForkId, EthSpec, SignedBeaconBlock, Slot, SubnetId};
 
-mod gossipsub_scoring_parameters;
+pub mod gossipsub_scoring_parameters;
 
 const MAX_IDENTIFY_ADDRESSES: usize = 10;
-pub const GOSSIPSUB_GREYLIST_THRESHOLD: f64 = -16000.0;
 
 /// Identifier of requests sent by a peer.
 pub type PeerRequestId = (ConnectionId, SubstreamId);
@@ -222,13 +223,7 @@ impl<TSpec: EthSpec> Behaviour<TSpec> {
         let active_validators = TSpec::minimum_validator_count();
         let current_slot = Slot::new(0);
 
-        let thresholds = PeerScoreThresholds {
-            gossip_threshold: -4000.0,
-            publish_threshold: -8000.0,
-            graylist_threshold: GOSSIPSUB_GREYLIST_THRESHOLD,
-            accept_px_threshold: 100.0,
-            opportunistic_graft_threshold: 5.0,
-        };
+        let thresholds = lighthouse_gossip_thresholds();
 
         let score_settings = PeerScoreSettings::new(chain_spec, &config.gs_config);
 

beacon_node/eth2_libp2p/src/config.rs

@@ -14,13 +14,15 @@ use sha2::{Digest, Sha256};
 use std::path::PathBuf;
 use std::time::Duration;
 
+/// The maximum transmit size of gossip messages in bytes.
 pub const GOSSIP_MAX_SIZE: usize = 1_048_576;
+/// This is a constant to be used in discovery. The lower bound of the gossipsub mesh.
+pub const MESH_N_LOW: usize = 6;
 
 // We treat uncompressed messages as invalid and never use the INVALID_SNAPPY_DOMAIN as in the
 // specification. We leave it here for posterity.
 // const MESSAGE_DOMAIN_INVALID_SNAPPY: [u8; 4] = [0, 0, 0, 0];
 const MESSAGE_DOMAIN_VALID_SNAPPY: [u8; 4] = [1, 0, 0, 0];
-pub const MESH_N_LOW: usize = 6;
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
 #[serde(default)]
@@ -138,8 +140,8 @@ impl Default for Config {
             .mesh_n_high(12)
             .gossip_lazy(6)
             .fanout_ttl(Duration::from_secs(60))
-            .history_length(6)
-            .max_messages_per_rpc(Some(10))
+            .history_length(12)
+            .max_messages_per_rpc(Some(500)) // Responses to IWANT can be quite large
             .history_gossip(3)
             .validate_messages() // require validation before propagation
             .validation_mode(ValidationMode::Anonymous)

beacon_node/eth2_libp2p/src/peer_manager/score.rs

@@ -5,7 +5,7 @@
 //! As the logic develops this documentation will advance.
 //!
 //! The scoring algorithms are currently experimental.
-use crate::behaviour::GOSSIPSUB_GREYLIST_THRESHOLD;
+use crate::behaviour::gossipsub_scoring_parameters::GREYLIST_THRESHOLD as GOSSIPSUB_GREYLIST_THRESHOLD;
 use serde::Serialize;
 use std::time::Instant;
 use strum::AsRefStr;