diff --git a/src/collections/mod.rs b/src/collections/mod.rs
index 872f1834a59e38ea0060e22458248874ec3858cb..dedba6bf5a17af413d57f54ac8858eebf0b38fbe 100644
--- a/src/collections/mod.rs
+++ b/src/collections/mod.rs
@@ -8,5 +8,5 @@ mod raw_vec;
 
 pub(crate) use string_pool::{StringPool, StringRef};
 pub(crate) use scoped_buffer::{ScopedBuffer, ScopedSection};
-pub(crate) use sets::DequeSet;
+pub(crate) use sets::{DequeSet, VecSet};
 pub(crate) use raw_vec::RawVec;
\ No newline at end of file
diff --git a/src/runtime2/consensus.rs b/src/runtime2/consensus.rs
index 69ca8e689d202ab1aae53a6991cc15503c604bc7..d9ae521f4c43e4a5c3d068a6dc8d0779c628dc1b 100644
--- a/src/runtime2/consensus.rs
+++ b/src/runtime2/consensus.rs
@@ -1,4 +1,5 @@
 use std::path::Component;
+use crate::collections::VecSet;
 use crate::protocol::eval::ValueGroup;
 use crate::runtime2::branch::{BranchId, ExecTree, QueueKind};
 use crate::runtime2::ConnectorId;
@@ -11,6 +12,16 @@ struct BranchAnnotation {
     port_mapping: Vec<PortAnnotation>,
 }
 
+pub(crate) struct LocalSolution {
+    component: ConnectorId,
+    final_branch_id: BranchId,
+    port_mapping: Vec<(PortIdLocal, BranchId)>,
+}
+
+pub(crate) struct GlobalSolution {
+
+}
+
 /// The consensus algorithm. Currently only implemented to find the component
 /// with the highest ID within the sync region and letting it handle all the
 /// local solutions.
@@ -26,6 +37,7 @@ pub(crate) struct Consensus {
     last_finished_handled: Option<BranchId>,
     // Gathered state (in case we are currently the leader of the distributed
     // consensus protocol)
+    encountered_peers: VecSet<ConnectorId>,
     // Workspaces
     workspace_ports: Vec<PortIdLocal>,
 }
@@ -42,6 +54,7 @@ impl Consensus {
             highest_connector_id: ConnectorId::new_invalid(),
             branch_annotations: Vec::new(),
             last_finished_handled: None,
+            encountered_peers: VecSet::new(),
             workspace_ports: Vec::new(),
         }
     }
@@ -220,7 +233,10 @@ impl Consensus {
     }
 
     pub fn handle_received_sync_header(&mut self, sync_header: &SyncHeader, ctx: &mut ComponentCtxFancy) {
-        todo!("should check IDs and maybe send sync messages");
+        debug_assert!(sync_header.sending_component_id != ctx.id)
+        if sync_header.highest_component_id > self.highest_connector_id {
+            // Sender has higher component ID
+        }
     }
 
     /// Checks data header and consults the stored port mapping and the
@@ -268,7 +284,7 @@ impl Consensus {
 
     /// Matches the mapping between the branch and the data message. If they
     /// match then the branch can receive the message.
-    pub(crate) fn branch_can_receive(&self, branch_id: BranchId, data_header: &DataHeader) -> bool {
+    pub fn branch_can_receive(&self, branch_id: BranchId, data_header: &DataHeader) -> bool {
         let annotation = &self.branch_annotations[branch_id.index as usize];
         for expected in &data_header.expected_mapping {
             // If we own the port, then we have an entry in the
@@ -286,6 +302,12 @@ impl Consensus {
 
         return true;
     }
+
+    // --- Internal helpers
+
+    fn forward_solutions_to(&mut self, target: ConnectorId) {
+        todo!("write")
+    }
 }
 
 /// Recursively goes through the value group, attempting to find ports.
diff --git a/src/runtime2/inbox2.rs b/src/runtime2/inbox2.rs
index ff2d65a34b542ca74445a72bbbb3499091ce8011..fdffe317a062dc1a0b20e61b0d22d2ae197fea79 100644
--- a/src/runtime2/inbox2.rs
+++ b/src/runtime2/inbox2.rs
@@ -29,7 +29,7 @@ pub(crate) struct DataHeader {
 }
 
 /// A data message is a message that is intended for the receiver's PDL code,
-/// but will also be handled by the consensus algrorithm
+/// but will also be handled by the consensus algorithm
 #[derive(Debug, Clone)]
 pub(crate) struct DataMessageFancy {
     pub sync_header: SyncHeader,
@@ -39,7 +39,8 @@ pub(crate) struct DataMessageFancy {
 
 #[derive(Debug)]
 pub(crate) enum SyncContent {
-
+    LocalSolution(), // sending a local solution to the leader
+    Notification, // just a notification (so message is about sending the SyncHeader)
 }
 
 /// A sync message is a message that is intended only for the consensus
@@ -47,6 +48,7 @@ pub(crate) enum SyncContent {
 #[derive(Debug)]
 pub(crate) struct SyncMessageFancy {
     pub sync_header: SyncHeader,
+    pub target_component_id: ConnectorId,
     pub content: SyncContent,
 }