diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1ad82e3..2e11e38 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -67,6 +67,9 @@
 /* The least MTU to use for probing */
 #define TCP_BASE_MSS		1024
 
+/* probing interval, default to 10 minutes as per RFC4821 */
+#define TCP_PROBE_INTERVAL	600
+
 /* Specify interval when tcp mtu probing will stop */
 #define TCP_PROBE_THRESHOLD	8