diff --git a/server/routerlicious/packages/protocol-definitions/src/sockets.ts b/server/routerlicious/packages/protocol-definitions/src/sockets.ts
index d927c1d1f5f1..32bbf2b10da0 100644
--- a/server/routerlicious/packages/protocol-definitions/src/sockets.ts
+++ b/server/routerlicious/packages/protocol-definitions/src/sockets.ts
@@ -46,6 +46,12 @@ export interface IConnect {
      * An optional nonce used during connection to identify connection attempts
      */
     nonce?: string;
+
+    /**
+     * Represents the version of document at client. It should match the version on server
+     * for connection to be successful.
+     */
+    epoch?: string;
 }
 
 /**