diff --git a/impl/src/layer2/connection.c b/impl/src/layer2/connection.c
index 2c458e4..ab9d970 100644
--- a/impl/src/layer2/connection.c
+++ b/impl/src/layer2/connection.c
@@ -10,7 +10,7 @@
 
 #define SEQ_NR_MASK 0xF
 
-result_t connection_init(connection_ctx_t *ctx, const ham64_t *my_addr, const ham64_t *peer_addr)
+result_t connection_init(connection_ctx_t *ctx, const ham64_t *my_addr, const ham64_t *peer_addr, connection_data_callback_t data_cb)
 {
 	ctx->last_acked_seq = 0;
 	ctx->next_expected_seq = 0;
@@ -22,6 +22,8 @@ result_t connection_init(connection_ctx_t *ctx, const ham64_t *my_addr, const ha
 	ctx->my_addr = *my_addr;
 	ctx->peer_addr = *peer_addr;
 
+	ctx->data_cb = data_cb;
+
 	ctx->conn_state = CONN_STATE_INITIALIZED;
 
 	return OK;
diff --git a/impl/src/layer2/connection.h b/impl/src/layer2/connection.h
index 038105c..a10e627 100644
--- a/impl/src/layer2/connection.h
+++ b/impl/src/layer2/connection.h
@@ -50,9 +50,10 @@ typedef struct connection_ctx_s {
  * \param ctx       The connection context to initialize.
  * \param my_addr   The local link layer address.
  * \param peer_addr The remote link layer address.
+ * \param data_cb   Callback for handling received payload data.
  * \returns OK if everything worked or a fitting error code.
  */
-result_t connection_init(connection_ctx_t *ctx, const ham64_t *my_addr, const ham64_t *peer_addr);
+result_t connection_init(connection_ctx_t *ctx, const ham64_t *my_addr, const ham64_t *peer_addr, connection_data_callback_t data_cb);
 
 /*!\brief Destroy the given layer 2 connection context.
  */
diff --git a/impl/test/layer2_over_udp/l2udptest.c b/impl/test/layer2_over_udp/l2udptest.c
index 21ac440..bf7d522 100644
--- a/impl/test/layer2_over_udp/l2udptest.c
+++ b/impl/test/layer2_over_udp/l2udptest.c
@@ -120,6 +120,17 @@ static result_t transmit(const uint8_t *data, size_t len)
 }
 
 
+void rx_data_to_tun(struct connection_ctx_s *conn, const uint8_t *data, size_t len)
+{
+	(void)conn;
+
+	int ret = write(m_tunfd, data, len);
+	if(ret < 0) {
+		LOG(LVL_ERR, "write(tun): %s", strerror(errno));
+	}
+}
+
+
 int main(int argc, char **argv)
 {
 	// initialize the console logger
@@ -146,7 +157,7 @@ int main(int argc, char **argv)
 	ham64_t my_address, peer_address;
 	ham64_encode(MY_CALL, &my_address);
 	ham64_encode(PEER_CALL, &peer_address);
-	RESULT_CHECK(connection_init(&l2conn, &my_address, &peer_address));
+	RESULT_CHECK(connection_init(&l2conn, &my_address, &peer_address, rx_data_to_tun));
 
 	// force connection into the established state
 	l2conn.conn_state = CONN_STATE_ESTABLISHED;
@@ -207,8 +218,6 @@ int main(int argc, char **argv)
 	pfd_bcast.fd = m_bcast_sock;
 	pfd_bcast.events = POLLIN;
 
-	unsigned rx_retries = 0;
-
 	double old = get_hires_time();
 	size_t total_bytes = 0;
 	double next_stats_print_time = old + 0.5;
@@ -341,8 +350,6 @@ int main(int argc, char **argv)
 				old = new;
 			}
 
-			rx_retries = 0;
-
 			fprintf(stderr, "r");
 		}
 	}