diff --git a/services/tunnelbroker/src/constants.rs b/services/tunnelbroker/src/constants.rs
new file mode 100644
--- /dev/null
+++ b/services/tunnelbroker/src/constants.rs
@@ -0,0 +1,2 @@
+pub const GRPC_TX_QUEUE_SIZE: usize = 32;
+pub const GRPC_PING_INTERVAL_MS: u64 = 3000;
diff --git a/services/tunnelbroker/src/main.rs b/services/tunnelbroker/src/main.rs
--- a/services/tunnelbroker/src/main.rs
+++ b/services/tunnelbroker/src/main.rs
@@ -1,3 +1,5 @@
+pub mod constants;
+
 #[cxx::bridge]
 mod ffi {
   unsafe extern "C++" {