add polling interval tlv
diff --git a/openflow_input/bsn_tlv b/openflow_input/bsn_tlv
index 4e12a2b..1d452ae 100644
--- a/openflow_input/bsn_tlv
+++ b/openflow_input/bsn_tlv
@@ -388,3 +388,9 @@
     uint16_t length;
     uint32_t value;
 };
+
+struct of_bsn_tlv_interval : of_bsn_tlv {
+    uint16_t type == 58;
+    uint16_t length;
+    uint32_t value;
+};